CN104346537A - Airborne radar radio frequency stealth performance evaluating method - Google Patents

Abstract

The invention belongs to the technical field of electronic countermeasures, in particular to a radio frequency stealth performance evaluation method of an airborne radar. The airborne radar radio frequency stealth performance evaluation method includes the following steps: obtain the detection equation of the airborne radar and the detection equation of each intercepting receiver; obtain the transmit peak power P _T of the airborne radar; step 3, according to the airborne radar The transmit peak power P _T of each intercepting receiver and the detection equation of each intercepting receiver can be obtained to obtain the power P _i of the signal received by the corresponding intercepting receiver; to obtain the probability that at least one intercepting receiver successfully intercepts the corresponding beam when the airborne radar transmits a beam The calculation formula of pi; according to the power P _I required by each intercepting receiver to detect the signal, and the power P _i of the signal received by the corresponding intercepting receiver _, it can be obtained that when the airborne radar transmits a beam, at least one intercepting receiver successfully intercepts the corresponding The probability p _i of the beam; according to the value of p _i , the radio frequency stealth performance of the airborne radar is evaluated.

Description

Airborne radar radio frequency stealth performance evaluation method

technical field

The invention belongs to the technical field of electronic countermeasures, in particular to a radio frequency stealth performance evaluation method of an airborne radar. The present invention mainly relates to the problem of how to quantitatively analyze the radio frequency stealth performance of airborne radar, which can be used in the actual battlefield environment to analyze the interception rate of signals, so as to evaluate the radio frequency stealth performance of airborne radar, and guide the radio frequency stealth performance of aircraft. Stealth system design. The invention can comprehensively consider various factors affecting the radio frequency stealth performance, and provide quantitative analysis.

Background technique

Nowadays, radar is facing threats from low-altitude penetration, stealth technology, electronic countermeasures and anti-radiation missiles. How to improve the survivability of radar in the current war has become one of the important research topics of various countries. With the development of passive detection technology, the radiation signal of the airborne radio frequency system has become the biggest hidden danger to reveal the whereabouts of the aircraft, which urgently requires the airborne radar to improve its radio frequency stealth performance to ensure the safety of the airborne platform. If radar wants to survive in various electronic countermeasure environments, it must improve its low interception and anti-jamming capabilities. The low-interception radar came into being in such an environment. This new system of radar requires that the probability of being detected by the enemy's detection system be minimized under the premise of effectively detecting targets, and the combat capability of the radar can be effectively improved. RF stealth (RF Stealth) has the same meaning as low interception, which refers to reducing the characteristics of radio frequency signals including radar, making the system more difficult to be detected and attacked. How to quantitatively and comprehensively evaluate the radio frequency stealth performance of the LPI (low probability of intercept) system plays a vital role in the development of radio frequency stealth technology.

At present, there are not many methods published publicly about analyzing the performance of radio frequency stealth, especially in the aspect of quantitative analysis, there are very few methods. The previous methods reflect the radio frequency stealth performance by the intercept factor, and can only compare the performance of the radar and the intercept receiver in the operating range, which is obviously not comprehensive enough. In the field of electronic countermeasures, the probability of interception is generally used to describe the ability of the intercepting receiver to detect radar signals. However, it is impossible to quantitatively compare the radio frequency stealth performance of the two systems simply by considering the probability of radar signal interception without considering the detection capability of the radar. . For example, when comparing the radio frequency stealth performance of two radars, if one of the radars is turned off for a long time, the signal interception rate of the radar is zero at this time, while the other radar is performing normal detection, the signal interception rate is greater than zero at this time, if so It is obviously incorrect to think that the radio frequency stealth performance of the shutdown radar is good. Therefore, these existing technologies are imperfect.

Contents of the invention

The purpose of the present invention is to propose an airborne radar radio frequency stealth performance evaluation method. The present invention starts with the relationship between the detection distance of the airborne radar and the interception distance of the passive interceptor, considers the detection performance of the radar comprehensively, and proposes a new quantitative analysis method for aircraft radio frequency The method of stealth performance, by establishing the corresponding calculation model, according to the calculation formula of the signal interception rate, can quantitatively analyze the influence of various factors on the radio frequency stealth performance, and gives the method of improving the radio frequency stealth performance of the aircraft.

In order to achieve the above-mentioned technical purpose, the present invention adopts the following technical solutions to achieve.

Airborne radar radio frequency stealth performance evaluation method includes the following steps:

Step 1, set a plurality of identical interception receivers within the irradiation range of each detection target of the airborne radar, and each interception receiver is located on a detection target of the corresponding airborne radar; Outward emission signals; get the detection equation of the airborne radar and the reconnaissance equation of each intercepting receiver;

Step 2, get the power S′ _r of the echo signal that the airborne radar needs to receive, according to the power S′ _r of the echo signal that the airborne radar needs to receive, and the detection equation of the airborne radar in step 1, get the machine The transmit peak power P _T of the onboard radar;

Step 3, according to the transmit peak power PT of the airborne radar and the detection equation of each intercepting receiver in step ₁ , obtain the power P _i of the signal received by the corresponding intercepting receiver;

Step 4, according to the probability p _F that each intercept receiver is tuned to the frequency of the airborne radar transmission signal, and the detection probability p _D that each intercept receiver detects the beam energy emitted by the airborne radar, the airborne radar emission A formula for calculating the probability p _i of the probability that at least one intercept receiver successfully intercepts the corresponding beam for one beam;

Step 5, obtain the power P _I required by each intercepting receiver to detect the signal, and substitute the power P _I required by each intercepting receiver to detect the signal and the power P _i of the signal received by the corresponding intercepting receiver into the airborne radar to transmit a In the calculation formula of the probability p _i that at least one intercepting receiver successfully intercepts the corresponding beam when the beam is transmitted, the probability p _i that at least one intercepting receiver successfully intercepts the corresponding beam when the airborne radar transmits a beam is obtained; When at least one intercept receiver successfully intercepts the value of the probability p _i of the corresponding beam, the radio frequency stealth performance of the airborne radar is evaluated.

The beneficial effects of the present invention are: 1) the present invention comprehensively considers the impact of five aspects such as time domain, air domain, frequency domain, energy and polarization domain on the radio frequency stealth performance of airborne radar, so it has great influence on the radio frequency stealth performance of airborne radar factors are considered very comprehensively. 2) The present invention provides a specific calculation method on the basis of the signal interception rate model, which can completely and quantitatively analyze the influence of each factor on the radio frequency stealth performance of the airborne radar. 3) The present invention not only considers the possibility that the radar is intercepted by the intercepting receiver, but also considers the detection performance of the radar, and analyzes the radio frequency stealth performance of the radar on the basis of the radar detection performance, so that the method is more comprehensive and objective, and can be used for The radio frequency stealth performance of two different systems is compared in the actual battlefield.

Description of drawings

Fig. 1 is the flow chart of airborne radar radio frequency stealth performance evaluation method of the present invention;

Figure 2 is a schematic diagram of the positional relationship between the airborne radar, the detection target and each interception receiver

Fig. 3 is a schematic diagram of the relationship between the search frame time of the intercept receiver and the intercept rate of the airborne radar signal under the situation of different intercept receiver sensitivities in the simulation experiment 1;

Fig. 4 is a schematic diagram of the relationship curve between the pulse repetition frequency and the interception rate of the airborne radar signal when the airborne radar is working in the simulation experiment 2;

Fig. 5 is a schematic diagram of the relationship curve between the target detection probability of the airborne radar and the interception rate of the airborne radar signal when the airborne radar has different exposure times to each intercepting receiver in the simulation experiment 3;

Fig. 6 is the schematic diagram of the relationship curve between the residence time of the launch beam of the airborne radar and the interception rate of the airborne radar signal when the duty cycle of the rectangular pulse signal emitted by the airborne radar is different in simulation experiment 4;

Fig. 7 is a schematic diagram of the relationship curve between the number of beams existing in the entire scanning space of the airborne radar and the cumulative signal interception rate of the airborne radar when the single-beam signal interception rate is different in simulation experiment 5.

detailed description

The present invention will be further described below in conjunction with accompanying drawing:

Referring to Fig. 1, it is a flow chart of the airborne radar radio frequency stealth performance evaluation method of the present invention. This airborne radar radio frequency stealth performance evaluation method comprises the following steps:

Step 1, set multiple identical intercepting receivers within the irradiation range of the airborne radar, each intercepting receiver is located on a detection target of the airborne radar; use the airborne radar to transmit signals outward, each intercepting receiver It is used to receive the signal emitted by the airborne radar; the detection equation of the airborne radar and the detection equation of each intercepting receiver are obtained.

Specifically, in step 1, in order to illustrate the relationship between the airborne radar detection range and the interception receiver interception distance, a schematic diagram of the positional relationship between the airborne radar, the detection target, and each interception receiver is constructed. Referring to FIG. 2 , it is a schematic diagram of the positional relationship among the airborne radar, the detection target and each intercepting receiver.

In order to detect the target, the airborne radar must first search within a certain range, considering the system loss, the detection equation of the airborne radar is:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; min</span>}}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 4</span>}}$

Among them, R _r is the maximum _{operating distance of the airborne radar, PT is the transmission peak power of the airborne radar, G T is} the gain of the airborne radar transmitting antenna, G _R is the gain of the airborne radar receiving antenna; λ is the transmission value of the airborne radar The carrier wavelength of the signal, _LR represents the system loss of the airborne radar, σ represents the target reflection cross-sectional area, and S _Rmin represents the sensitivity of the airborne radar receiver.

The detection equation for each intercept receiver is:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; min</span>}}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}}$

Among them, R _I is the maximum intercepting distance of each intercepting receiver, G _TI is the antenna gain of the airborne radar in the direction of the intercepting receiver, G _I is the receiving antenna gain of the intercepting receiver; L _I is the system Loss, S _Imin is the sensitivity of each intercept receiver.

It can be seen that in step 1, the relationship between the airborne radar detection distance and the interception receiver interception distance is analyzed.

Step 2, get the power S′ _r of the echo signal that the airborne radar needs to receive, according to the power S′ _r of the echo signal that the airborne radar needs to receive, and the detection equation of the airborne radar in step 1, get the machine The transmit peak power P _T of the radar.

Its specific sub-steps are:

(2.1) The airborne radar receiver satisfies the relation p _d = p _d (p _fa , SNR _r ) when performing single pulse detection probability, p _d represents the target detection probability of the airborne radar, and p _fa represents the airborne radar’s Target detection false alarm probability, SNR _r represents the signal-to-noise ratio of the echo signal received by the airborne radar. That is to say, the target detection probability p _d of the airborne radar is a function of the target detection false alarm probability p _fa of the airborne radar and the signal-to-noise ratio SNR _r of the echo signal received by the airborne radar. If the target detected by the airborne radar is a Swerling I type target, the target detection probability p _d of the airborne radar is:

${\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; fa</span>}}^{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; SNR</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}}$

Therefore, the signal-to-noise ratio SNR _r of the echo signal received by the airborne radar is expressed as:

${\mathrm{<span\; class="notranslate">\; SNR</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; fa</span>}}}{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; .</span>$

Among them, lg represents the logarithm with base 10, p _d represents the target detection probability of the set airborne radar, and p _fa represents the set target detection false alarm probability of the airborne radar.

Assuming that the receiver of the airborne radar is an ideal receiver, the power N _i of the noise received by the airborne radar is: N _i =kT ₀ B _r F _n .

The power S _r of the echo signal received by the airborne radar receiver when performing monopulse detection probability is obtained:

S _r =SNR _r N _i =SNR _r k ₀ T ₀ B _r F _n

Among them, SNR _r is the signal-to-noise ratio of the echo signal received by the airborne radar, N _i represents the noise power received by the airborne radar, k ₀ represents the Boltzmann constant, T ₀ represents the noise temperature of the airborne radar receiver ( For example, 290K), B _r represents the bandwidth of the airborne radar receiver to receive the signal, and F _n represents the noise figure of the airborne radar receiver.

(2.2) In actual situations, the airborne radar receiver needs to perform coherent accumulation processing on the received signals. After performing coherent accumulation of M equal-amplitude pulses on the received signals, the signal-to-noise power ratio can be increased to The original M times, so that the detection factor is reduced to the original 1/M, and M is a natural number greater than 1. Therefore, when the threshold detection reaches the same signal-to-noise ratio, the signal-to-noise ratio of a single pulse required by the detector input of the airborne radar receiver will be reduced to 1/M when it is not accumulated. Then the power S′ _r of the echo signal that the airborne radar needs to receive is obtained,

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; SNR</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}$

Among them, M is the number of pulses accumulated by the airborne radar receiver (the number of antenna dwell time pulses), S _r represents the power of the echo signal received by the airborne radar receiver when the probability of single pulse detection is carried out; k ₀ represents the Bohr Zeman's constant, T ₀ represents the noise temperature of the airborne radar receiver (for example, 290K), B _r represents the bandwidth of the airborne radar receiver receiving signals, and F _n represents the noise figure of the airborne radar receiver. In the embodiment of the present invention, the number of pulses M accumulated by the airborne radar receiver is: M=T _D f _r ; wherein, T _D is the residence time of the airborne radar's transmit beam sweeping point target, and _fr is the airborne The pulse repetition frequency at which the radar operates.

(2.3) According to the power S′ _r of the echo signal that the airborne radar needs to receive and the detection equation of the airborne radar in step 1, the transmit peak power P _T of the airborne radar is obtained:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; fa</span>}}}{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}}{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;\; T</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}$

Among them, S′ _r is the power of the echo signal that the airborne radar needs to receive, R _r represents the maximum operating distance of the airborne radar, G _T is the gain of the airborne radar transmitting antenna, G _R is the gain of the airborne radar receiving antenna; λ is the carrier wavelength of the airborne radar transmission signal, _LR represents the system loss of the _airborne radar, _σ represents the target reflection cross-sectional area; pulse repetition frequency when the radar is working; p _d represents the target detection probability of the set airborne radar, p _fa represents the target detection false alarm probability of the set airborne radar; k ₀ represents the Boltzmann constant, T ₀ represents The noise temperature of the airborne radar receiver (for example, 290K), B _r represents the bandwidth of the airborne radar receiver receiving signals, and F _n represents the noise figure of the airborne radar receiver.

In step 3, according to the transmit peak power PT of the airborne radar and the detection equation of each intercepting receiver in step ₁ , the power P _i of the signal received by the corresponding intercepting receiver is obtained.

Its specific sub-steps are:

(3.1) According to the transmission peak power P _T of the airborne radar and the detection equation of each intercepting receiver in step 1, the power P _i of the signal received by the corresponding intercepting receiver is obtained:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; fa</span>}}}{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}$

Among them, R represents the distance between the airborne radar and the corresponding intercept receiver, G _TI is the antenna gain of the airborne radar in the direction of the corresponding intercept receiver, G _I is the receiving antenna gain of the corresponding intercept receiver; L _I is the corresponding intercept receiver The system loss of , λ is the carrier wavelength of the airborne radar transmission signal, and PT is the transmission peak power of the airborne radar _. T _D is the residence time of the airborne radar's transmitting beam sweeping point target, f _r is the pulse repetition frequency when the airborne radar is working; _LR is the system loss of the airborne radar, σ is the target reflection cross-sectional area; p _d represents the target detection probability of the set airborne radar, p _fa represents the target detection false alarm probability of the set airborne radar; k ₀ represents the Boltzmann constant, T ₀ represents the noise temperature of the airborne radar receiver (for example is 290K), B _r represents the bandwidth of the airborne radar receiver to receive the signal, and F _n represents the noise figure of the airborne radar receiver. G _T is the gain of the airborne radar transmitting antenna, and G _R is the gain of the airborne radar receiving antenna.

(3.2) When the airborne radar is an airborne pulse Doppler radar, the bandwidth of the matched filter (the bandwidth of the received signal of the airborne radar receiver) B _r and the pulse width τ of the rectangular pulse emitted by the airborne radar satisfy the following Relational formula: B _r =1/τ. and there is,

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}$

Among them, T _r is the pulse repetition period when the airborne radar is working, let η represent the duty cycle of the rectangular pulse signal emitted by the airborne radar, and have

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}$

Then when the airborne radar is an airborne pulse Doppler radar, the power P _i corresponding to the signal received by the intercept receiver is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; fa</span>}}}{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}$

As an improvement of the embodiment of the present invention, considering the influence of antenna polarization on the signal interception rate, in the process of electromagnetic wave propagation, the change of polarization will be affected by factors such as propagation distance and frequency, so the interception of the signal received by the receiver and the interception The receiving antenna of the receiver may have mismatch loss due to different polarization modes. The polarization loss coefficient is represented by L _p , which indicates the ratio of the actual received power of the intercept receiver to the power without polarization loss. Then the power P _i of the signal received by the corresponding intercept receiver is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; fa</span>}}}{\mathrm{<span\; class="notranslate">\; lg</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; \&sigma;\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}$

Among them, L _p represents the polarization loss coefficient of the corresponding intercept receiver.

Step 4, according to the probability p _F of each intercept receiver tuned to the frequency of the airborne radar transmission signal, and the detection probability p _D of each intercept receiver detecting the beam energy emitted by the airborne radar, the airborne radar emission A formula for calculating the probability p _i of the probability that at least one intercept receiver successfully intercepts the corresponding beam for a beam.

Its specific sub-steps are:

(4.1) For the convenience of analysis, it is assumed that the intercept receiver is located on the target. The probability of interception problem can be simulated by a series of repeated independent experiments, each experiment having two possible outcomes of constant probability: interception or non-interception, which is called a Bernoulli experiment.

Assuming that the airborne radar irradiates each intercepting receiver n times, and the interception probability of each intercepting receiver is p during each irradiation, the probability p _r ( k,n,p). The probability p _r (k,n,p) of each intercepting receiver successfully intercepting the transmitted signal of the airborne radar for k times is:

${\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left(\begin{array}{c}\mathrm{<span\; class="notranslate">\; no</span>}\\ \mathrm{<span\; class="notranslate">\; k</span>}\end{array}\right){\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; k</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; k</span>}}$

Among them, k≤n, $\left(\begin{array}{c}\mathrm{no}\\ k\end{array}\right)$ for

In practice, the probability of intercept per shot is small (p is small) and the number of shots is large (n is large), which allows a Poisson approximation to the binomial. Assuming that the airborne radar irradiates the intercepting receiver n times, and the interception probability of each intercepting receiver is p during each irradiation, the probability p _r (k, l), l=np. The probability p _r (k,l) of each intercept receiver successfully intercepting the transmitted signal of the airborne radar for k times is:

${\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}^{\mathrm{<span\; class="notranslate">\; k</span>}}}{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; !</span>}{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; l</span>}}$

Among them, l=np, k represents the interception times.

(4.2) Obtain the calculation formula of the probability p _r of the probability that at least one intercept receiver successfully intercepts the corresponding beam when the airborne radar transmits a beam, obviously, p _r =1-p _r (0,l)=1-e ^-l .

Get an approximation for l:

$\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}\frac{\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; OT</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}$

Among them, A _F is the coverage area of the airborne radar transmitting beam, the unit is km ² , D _I refers to the density of intercepting receivers per square kilometer, and T _OT refers to the irradiation time of the airborne radar on each intercepting receiver , T _I represents the frame time of each intercepting receiver (the time for each intercepting receiver to receive a frame of signal), and min(·) represents the minimum value.

Find the probability of each intercept receiver encountering the airborne radar beam in the time domain. Under normal circumstances, the exposure time T _OT of the airborne radar to each intercepting receiver is much smaller than the frame time T _I of each intercepting receiver, so when the airborne radar sends out signals, each intercepting receiver The probability of detecting the position of the airborne radar is about . That is to say, the probability that each intercept receiver meets the airborne radar beam in the time domain is $\frac{\min (T_{\mathrm{OT}},T_I)}{T_I},\frac{\min (T_{\mathrm{OT}},T_I)}{T_I}\&ap;\frac{T_{\mathrm{OT}}}{T_I}.$

(4.3) According to the probability p _F that each intercept receiver is tuned to the frequency of the airborne radar transmitted signal, and the detection probability p _D that each intercept receiver detects the beam energy emitted by the airborne radar, a The probability that at least one intercepting receiver successfully intercepts the transmitted signal of the airborne radar is corrected when the beam is transmitted, and the calculation formula of the probability p _i of the probability that at least one intercepting receiver successfully intercepts the corresponding beam is obtained when the airborne radar transmits a beam.

When deriving the probability that at least one intercept receiver successfully intercepts the corresponding beam when the airborne radar transmits a beam, it is also necessary to consider the probability p _F that each intercept receiver is tuned to the frequency at which the airborne radar transmits the signal, and the probability that each intercept receiver The probability of detection p _D that the aircraft detects the beam energy emitted by the airborne radar. Therefore, combining the intercept probability of the receiver in the time domain, frequency domain, air domain and energy domain, the calculation formula for the probability that at least one intercept receiver successfully intercepts the corresponding beam when the airborne radar transmits a beam can be obtained:

${\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}\frac{\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; OT</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; \}</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}$

Among them, p _i represents the probability that at least one intercept receiver successfully intercepts the corresponding beam when the airborne radar transmits a beam, A _F is the coverage area of the airborne radar transmitted beam, the unit is km ² , D _I refers to the area per square kilometer T _OT represents the exposure time of the airborne radar to each intercept receiver, T _I represents the frame time of each intercept receiver, min( ) represents the minimum value; p _D represents the The receiver detects the detection probability of the beam energy emitted by the airborne radar, _pF represents the probability that each intercepting receiver is tuned to the frequency of the airborne radar transmitted signal.

because , then the probability p _i that at least one intercept receiver successfully intercepts the corresponding beam when the airborne radar transmits a beam can be approximately expressed as:

${\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&ap;</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; OT</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}$

If the probability p _i of at least one intercepting receiver successfully intercepting the corresponding beam when the airborne radar transmits a beam is far less than 1, then the calculation formula for the probability p _i of at least one intercepting receiver successfully intercepting the corresponding beam when the airborne radar transmits a beam can be Simplifies to:

${\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&ap;</span>\mathrm{<span\; class="notranslate">\; MF</span>}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; )</span>}^{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; OT</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}$

Among them, MF represents the main lobe coverage area when the transmission signal gain of the airborne radar is 3dB, P _I is the power required by each intercepting receiver to detect the signal, D _I refers to the density of the intercepting receiver, and T _I represents the power of each intercepting receiver. The frame time of the receiver, T _OT represents the exposure time of the airborne radar to each intercepting receiver; C ₀ represents the coverage area/sensitivity scale factor of the airborne radar (when the aperture of the transmitting antenna of the airborne radar is an unweighted rectangular When the aperture is used, C ₀ is 0.2; when the aperture of the airborne radar transmitting antenna is an unweighted circular aperture, C ₀ is 0.477), and P _i represents the power of the signal received by the corresponding intercept receiver.

(4.4) If there are multiple beams in the entire scanning space of the airborne radar, then the probability P _icum of at least one interception occurring in the entire scanning space of the airborne radar (the probability that at least one intercepting receiver successfully intercepts the beam) is obtained Calculation formula:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; icum</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\underset{{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}{\mathrm{<span\; class="notranslate">\; \&Pi;</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{{\mathrm{<span\; class="notranslate">\; ik</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}<span\; class="notranslate">\; )</span>$

Among them, p _ik' represents the probability that the k'th beam is successfully intercepted by at least one intercept receiver in the entire scanning space of the airborne radar, k' ranges from 1 to n', and n' is the existence of number of beams.

Step 5, obtain the power P _I required by each intercepting receiver to detect the signal, and substitute the power P _I required by each intercepting receiver to detect the signal and the power P _i of the signal received by the corresponding intercepting receiver into the airborne radar to transmit a In the calculation formula of the probability p _i that at least one intercepting receiver successfully intercepts the corresponding beam when the beam is transmitted, the probability p _i that at least one intercepting receiver successfully intercepts the corresponding beam when the airborne radar transmits a beam is obtained; When at least one intercept receiver successfully intercepts the value of the probability p _i of the corresponding beam, the radio frequency stealth performance of the airborne radar is evaluated.

Its specific sub-steps are:

(5.1) For each intercept receiver, a non-coherent accumulation technique can be used in the process of intercepting the signal, so that the corresponding intercept receiver operates without knowing the details of the transmitted waveform. The non-coherent accumulation gain of each intercept receiver is about , M is the number of pulses accumulated by the airborne radar receiver. At this time, the power _PI required by each intercepting receiver to detect the signal is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; min</span>}}}{\mathrm{<span\; class="notranslate">\; 3.55</span>}\sqrt{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}}$

Among them, S _Imin is the sensitivity of each intercepting receiver, T _D is the dwell time of the airborne radar's transmitting beam sweeping the point target, f _r is the pulse repetition frequency of the airborne radar when it is working.

(5.2) According to the power P _I required by each intercepting receiver to detect the signal obtained in sub-step (5.1), the probability p _i of at least one intercepting receiver successfully intercepting the corresponding beam is obtained when the airborne radar transmits a beam:

$p_i\&ap;\mathrm{MF}\&CenterDot;{\{2\&CenterDot;[\frac{{4\mathrm{\&pi;R}}^2(\frac{\lg P_{\mathrm{fa}}}{\lg P_d}-1)k_0{T}_0{f}_{\mathrm{no}}{L}_I{L}_p}{{\mathrm{\&sigma;\; L}}_R}\frac{G_{\mathrm{Ti}}{G}_I}{G_T{G}_R}\frac{1}{\mathrm{\&eta;}}]/(\frac{\sqrt{T_{\mathrm{D.}}}{S}_{I\min }}{3.55\sqrt{f_r}}\left)\right\}}^{C_0}{\mathrm{D.}}_I{T}_{\mathrm{OT}}/T_I$ Among them, MF represents the main lobe coverage area when the transmit signal gain of the airborne radar is 3dB, D _I refers to the density of intercepting receivers, T _I represents the frame time of each intercepting receiver, T _OT represents the airborne radar’s C ₀ represents the coverage area/sensitivity scale factor of the airborne radar (when the aperture of the transmitting antenna of the airborne radar is an unweighted rectangular aperture, C ₀ is 0.2; when the transmitting antenna of the airborne radar When the aperture of the antenna is an unweighted circular aperture, C ₀ is 0.477).

From the expression of p _i in the sub-step (5.2), it can be seen that the radio frequency stealth performance of the airborne radar (the probability that the transmitted signal of the airborne radar is intercepted) is related to the main lobe coverage area when the gain of the transmitted signal of the airborne radar is 3dB MF, the system loss L _R of the airborne radar, the antenna gain G _TI of the airborne radar in the direction corresponding to the intercepting receiver, the residence time T _D of the target at the point where the airborne radar transmits the beam, and the rectangular pulse emitted by the airborne radar The duty ratio η of the signal, the pulse repetition frequency f _r when the airborne radar is working, and the irradiation time T _OT of the airborne radar to each intercepting receiver are related to factors such as the receiving antenna gain G _I , The system loss L _I of the corresponding intercept receiver, the sensitivity S _Imin of each intercept receiver, the search frame time T _I of each intercept receiver, and the density D _I of the intercept receiver are related.

So far, the probability p _i of at least one intercept receiver successfully intercepting the corresponding beam when the airborne radar transmits a beam can be obtained, and then according to the probability p _i of at least one intercept receiver successfully intercepting the corresponding beam when the airborne radar transmits a beam Value, to evaluate the radio frequency stealth performance of airborne radar. The smaller the value of _pi , the better the radio frequency stealth performance of the airborne radar, and vice versa, the worse the radio frequency stealth performance of the airborne radar.

In the embodiment of the present invention, it is necessary to arrange several identical intercepting receivers on the ground first, the density D _I of the intercepting receivers, and the relevant parameters of each intercepting receiver (including the receiving antenna gain G _I of the corresponding intercepting receiver, the corresponding The system loss L _I of the intercept receiver, the sensitivity S _Imin of each intercept receiver, and the search frame time T _I of each intercept receiver are all known information. The relevant parameters of the airborne radar in the expression of sub-step (5.2) p _i are also known.

Effect of the present invention can be further illustrated by following simulation experiments:

1) Simulation conditions

The main lobe coverage area MF is 160km ² when the transmit signal gain of the airborne radar is 3dB, the density D _I of intercepting receivers (located on the ground) is 0.01 units/km ² , and the sensitivity S _Rmin of the airborne radar receiver is ＝-60dBm, The bandwidth B _r of the signal received by the airborne radar receiver is 1 GHz. The sensitivity S _Imin of each intercept receiver = -100dBw, the target reflection cross-sectional area σ = 100m ² , the noise figure F _n of the airborne radar receiver = 3dB, the distance between the airborne radar and the corresponding intercept receiver = 100km, The transmit antenna gain of the airborne radar G _T =40dB, the antenna gain G _TI of the airborne radar in the direction corresponding to the intercepting receiver =-20dB, and the receiving antenna gain G I of the corresponding intercepting receiver G _I =30dB. The dwell time T _D of the airborne radar's emission beam sweeping point target = 0.02s, the irradiation time T _OT of each intercepting receiver by the airborne radar = 0.2s; the system loss L _R of the airborne radar = -3dB, The system loss L _I of the corresponding intercept receiver =-6dB, the polarization loss coefficient L _p =1 of the corresponding intercept receiver; the coverage area/sensitivity scale factor C ₀ of the airborne radar =0.477, and the Boltzmann constant k ₀ = 1.38×10 ^-23 , the noise temperature T ₀ of the airborne radar receiver = 290K; the target detection probability of the airborne radar p _d = 90%, the target detection false alarm probability of the airborne radar p _fa = 10 ^-8 , the airborne radar The duty cycle of the rectangular pulse signal emitted by the radar is η=0.1.

2) Simulation content and results

In the simulation experiment 1, the sensitivity of the intercepting receiver and the influence of the frame time on the signal interception rate are simulated, and the simulation results are shown in Figure 3. Referring to Fig. 3, it is the intercept rate of the search frame time of the intercept receiver and the airborne radar signal (at least one intercept receiver successfully intercepts when the airborne radar transmits a beam) under the situation of different intercept receiver sensitivities in simulation experiment 1 Schematic diagram of the relationship between the probability p _i ) of the corresponding beam. In Fig. 3, the horizontal axis represents the search frame time of the intercepting receiver, and the unit is s, and the vertical axis represents the interception rate of the airborne radar signal; different curves correspond to different sensitivity of the intercepting receiver. In the case of certain airborne radar transmission power and beam irradiation area, the sensitivity and search frame time of different types of interception receivers will directly affect its interception rate of radar signals. According to different sensitivities and search frame times of the intercepting receivers, the intercepting rate of the airborne radar signal can be obtained by using the present invention. It can be seen from Fig. 3 that in order to achieve a higher signal interception rate, the interception receiver must adopt higher sensitivity and shorter search frame time. The shorter the search frame time of the intercept receiver, the greater the signal intercept rate of the radar. For the intercept receiver, the best strategy is to match its search frame time with the radar target time, and the signal intercept rate is the largest at this time.

Simulation experiment 2, simulates the influence of airborne radar and intercept receiver antenna gain on the signal intercept rate, and the simulation results are shown in Figure 4. make , the values of β are different for different curves in Fig. 4. Referring to FIG. 4 , it is a schematic diagram of the relationship curve between the pulse repetition frequency and the interception rate of the airborne radar signal in the simulation experiment 2 when the airborne radar is working. In Figure 4, the horizontal axis represents the pulse repetition frequency when the airborne radar is working, and the unit is MHz, and the vertical axis represents the interception rate of the airborne radar signal; it can be seen from Figure 4 that the larger the β, the greater the signal interception rate. Therefore, in order to improve the radio frequency stealth performance of the radar, it is necessary to increase the gain of the airborne radar transmitting antenna, and since the intercepting receiver is often not easy to intercept the main lobe of the airborne radar transmitting signal, it is intercepted from the side lobe in most cases, so , using a low-sidelobe antenna and using windowing to reduce the antenna sidelobe level can reduce the antenna gain of the airborne radar in the direction corresponding to the intercepting receiver, thereby reducing the airborne radar signal interception rate and improving the aircraft's radio frequency stealth performance. It can also be seen from Figure 4 that reducing the pulse repetition frequency when the airborne radar is working can also reduce the interception rate of the airborne radar signal, so the pulse repetition frequency when the airborne radar is working can be appropriately reduced to improve the radio frequency stealth performance of the aircraft .

In simulation experiment 3, the target detection probability of the airborne radar and the influence of the airborne radar's irradiation time on each intercepting receiver on the airborne radar signal interception rate are studied. The simulation results are shown in Figure 5. Referring to FIG. 5 , it is a schematic diagram of the relationship curve between the target detection probability of the airborne radar and the interception rate of the airborne radar signal when the irradiation time of the airborne radar to each intercepting receiver is different in the simulation experiment 3. In Fig. 5, the horizontal axis represents the target detection probability of the airborne radar, and the vertical axis represents the signal interception rate of the airborne radar. For different curves, the irradiation time of the airborne radar to each intercepting receiver is different. It can be seen from Figure 5 that when the target detection probability of the airborne radar is small, the interception rate of the airborne radar signal gradually increases with the increase of the target detection probability of the airborne radar, but when the target of the airborne radar When the detection probability increases to a certain value, such as greater than 90%, the target detection probability of the airborne radar only needs to be increased by a small value, which will lead to a rapid increase in the interception rate of the airborne radar signal, so the target of the airborne radar The detection probability should not be too large, and the target detection probability of the airborne radar can be controlled according to actual needs. It can also be seen from Figure 5 that for the interception rate of airborne radar signals, the exposure time of the airborne radar to each intercepting receiver is also very important, because the ability of the airborne radar to detect the target depends on the energy irradiated to the target. size, and this energy is proportional to the number of pulses received by the target. It can be seen from Figure 5 that when the target detection probability of the airborne radar is the same, the longer the irradiation time of the airborne radar to each intercepting receiver, the greater the interception rate of the airborne radar signal. Therefore, in order to achieve the effect of low interception, the airborne radar needs to reduce the irradiation time of the target.

Simulation experiment 4 is to study the influence of the residence time of the airborne radar's transmit beam sweeping point target and the duty cycle of the airborne radar's transmitted rectangular pulse signal on the airborne radar signal interception rate. The simulation diagram is shown in Figure 6. Referring to FIG. 6 , it is a schematic diagram of the relationship curve between the dwell time of the transmitted beam of the airborne radar and the interception rate of the airborne radar signal when the duty cycle of the rectangular pulse signal transmitted by the airborne radar is different in the simulation experiment 4. In Figure 6, the horizontal axis represents the residence time of the airborne radar’s emission beam sweeping point target, the unit is s, the vertical axis represents the airborne radar signal interception rate, and the proportion of the rectangular pulse signal emitted by the airborne radar corresponding to different curves The void ratio is different. It can be seen from Figure 6 that the longer the dwell time of the airborne radar’s transmit beam sweeping point target is, the better the radio frequency stealth performance of the airborne radar is (the lower the interception rate of the airborne radar signal is). The principle is: when the residence time of the airborne radar’s transmit beam sweeping point target increases, the number of pulses coherently accumulated by the airborne radar increases, and the power required to transmit decreases, which is conducive to improving the LPI (low probability of intercept, low Interception probability) performance, on the other hand, when the residence time of the airborne radar’s transmit beam sweeping point target increases, the gain of the intercept receiver for non-coherent accumulation will also increase, which is not conducive to the radar’s LPI (low probability ofintercept, low probability of intercept) performance. However, since the increase of the dwell time of the airborne radar's transmitting beam sweeps the point target, the gain of the coherent accumulation of the airborne radar is greater than the increase of the incoherent accumulation gain of the intercepting receiver, so in general, increasing the airborne radar The residence time of the radar transmitting beam sweeping point target is beneficial to improve the radar radio frequency stealth performance. The dwell time of the airborne radar’s transmit beam sweeping the point target is related to the frame time and scanning speed of the radar scan. It can be seen from Figure 6 that when the airborne radar’s transmit beam sweeps the dwell time of the point target When the airborne radar signal interception rate is relatively sensitive to the change of the residence time of the airborne radar’s transmit beam sweep point target, when the airborne radar transmit beam sweep point target’s dwell time is relatively large, the airborne radar The residence time of the target at the scanning point of the transmitting beam has little effect on the interception rate of the airborne radar signal, so the scanning strategy needs to be controlled according to the actual situation. It can also be seen from Figure 6 that the greater the duty cycle of the rectangular pulse signal emitted by the airborne radar, the lower the interception rate of the airborne radar signal, which is also consistent with the common understanding that the rectangular pulse signal emitted by the airborne radar The larger the duty cycle of , the more dispersed the signal power in the time domain and the lower the peak power, resulting in better radio frequency stealth performance. When the duty cycle is 1, the radar emits continuous waves, and the signal interception rate is the smallest at this time, but when the duty cycle is too large, the distance resolution of radar detection will decrease. This problem can be solved by pulse compression .

In simulation experiment 5, the influence of the number of beams on the cumulative signal interception rate is simulated, and the simulation diagram is shown in Figure 7. Referring to Fig. 7, it is the number of beams and the cumulative signal interception rate of the airborne radar (i.e. the entire scanning space of the airborne radar in the present invention) that exist in the whole scanning space of the airborne radar when the single-beam signal interception rate is different in the simulation experiment 5. Schematic diagram of the relationship curve of the probability P _icum that at least one interception occurs within . In Figure 7, the horizontal axis represents the number of airborne radar beams existing in the entire scanning space of the airborne radar, and the vertical axis represents the cumulative signal interception rate of the airborne radar. The single beam signal interception rates of different curves in Figure 7 are different, and the airborne The number of airborne radar beams present in the entire scanning space of the radar varies from 0 to 200. It can be seen from Figure 7 that even if the interception probability of a single beam is low, the interception probability of each beam can reach a high cumulative value after the amplification of the total number of beams. That is to say, it is not only necessary to optimize parameters such as the irradiation time of the target, but also to minimize the number of airborne radar beams existing in the entire scanning space of the airborne radar.

In summary, this simulation verifies the correctness, effectiveness and reliability of the present invention.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (9)

1. The airborne radar radio frequency stealth performance evaluation method is characterized in that, comprising the following steps: Step 1, set a plurality of identical interception receivers within the irradiation range of each detection target of the airborne radar, and each interception receiver is located on a detection target of the corresponding airborne radar; Outward emission signals; get the detection equation of the airborne radar and the reconnaissance equation of each intercepting receiver; Step 2, get the power S′ _r of the echo signal that the airborne radar needs to receive, according to the power S′ _r of the echo signal that the airborne radar needs to receive, and the detection equation of the airborne radar in step 1, get the machine The transmit peak power P _T of the onboard radar; Step 3, according to the transmit peak power PT of the airborne radar and the detection equation of each intercepting receiver in step ₁ , obtain the power P _i of the signal received by the corresponding intercepting receiver; Step 4, according to the probability p _F of each intercept receiver tuned to the frequency of the airborne radar transmission signal, and the detection probability p _D of each intercept receiver detecting the beam energy emitted by the airborne radar, the airborne radar emission A formula for calculating the probability p _i of the probability that at least one intercept receiver successfully intercepts the corresponding beam for one beam; Step 5, obtain the power P _I required by each intercepting receiver to detect the signal, and substitute the power P _I required by each intercepting receiver to detect the signal and the power P _i of the signal received by the corresponding intercepting receiver into the airborne radar to transmit a In the calculation formula of the probability p _i that at least one intercepting receiver successfully intercepts the corresponding beam when the beam is transmitted, the probability p _i that at least one intercepting receiver successfully intercepts the corresponding beam when the airborne radar transmits a beam is obtained; When at least one intercept receiver successfully intercepts the value of the probability p _i of the corresponding beam, the radio frequency stealth performance of the airborne radar is evaluated. 2. airborne radar radio frequency stealth performance evaluation method as claimed in claim 1, is characterized in that, in step 1, the detection equation of described airborne radar is: ${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}\mathrm{<span\; class="notranslate">\; min</span>}}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 4</span>}}$ Among them, R _r is the maximum _{operating distance of the airborne radar, PT is the transmission peak power of the airborne radar, G T is} the gain of the airborne radar transmitting antenna, G _R is the gain of the airborne radar receiving antenna; λ is the transmission value of the airborne radar The carrier wavelength of the signal, _LR represents the system loss of the airborne radar, σ represents the target reflection cross-sectional area, and S _Rmin represents the sensitivity of the airborne radar receiver; The detection equation for each intercept receiver is: ${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; min</span>}}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}}$ Among them, R _I is the maximum intercept distance of each intercept receiver, G _TI is the antenna gain of the airborne radar in the direction of the corresponding intercept receiver, G _I is the receiving antenna gain of the corresponding intercept receiver; L _I is the corresponding intercept receiver System loss, S _Imin is the sensitivity of the corresponding intercept receiver; In step 2, the process of obtaining the power _S′r of the echo signal that the airborne radar needs to receive is: Obtain the signal-to-noise ratio SNR _r of the echo signal received by the airborne radar, and the power N _i of the noise received by the airborne radar; obtain the power of the echo signal received by the airborne radar receiver when performing single-pulse detection probability S _r , S _r = SNR _r N _i ; According to the pulse number M accumulated by the airborne radar receiver, the power S′ _r of the echo signal that the airborne radar needs to receive is obtained, $S_r^{\&prime;}=\frac{1}{m}{S}_r.$ 3. airborne radar radio frequency stealth performance evaluation method as claimed in claim 1, is characterized in that, in step 2, the transmission peak power PT of airborne _radar is: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}$ Among them, S′ _r is the power of the echo signal that the airborne radar needs to receive, R _r represents the maximum operating distance of the airborne radar, G _T is the gain of the airborne radar transmitting antenna, G _R is the gain of the airborne radar receiving antenna; λ is the carrier wavelength of the airborne radar transmitting signal, _LR represents the system loss of the airborne radar, and σ represents the target reflection cross-sectional area. 4. airborne radar radio frequency stealth performance evaluation method as claimed in claim 1, is characterized in that, in step 3, the power Pi corresponding to intercepting the signal that receiver _receives is: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$ Among them, _PT represents the transmission peak power of the airborne radar, R represents the distance between the airborne radar and the corresponding intercept receiver, G _TI is the antenna gain of the airborne radar in the direction of the corresponding intercept receiver, G _I is the corresponding intercept receiver Receiving antenna gain; L _I is the system loss of the corresponding intercept receiver, and λ is the carrier wavelength of the airborne radar transmitting signal. 5. airborne radar radio frequency stealth performance evaluation method as claimed in claim 1, is characterized in that, in step 3, when airborne radar is airborne pulse Doppler radar, correspondingly intercepts the power of the signal that receiver receives _Pi is: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; fa</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}$ Among them, R represents the distance between the airborne radar and the corresponding intercept receiver, G _TI is the antenna gain of the airborne radar in the direction of the corresponding intercept receiver, G _I is the receiving antenna gain of the corresponding intercept receiver; L _I is the corresponding intercept receiver system loss; p _d represents the target detection probability of the set airborne radar, p _fa represents the target detection false alarm probability of the set airborne radar; k ₀ represents the Boltzmann constant, T ₀ represents the airborne radar receiving The noise temperature of the aircraft, F _n represents the noise figure of the airborne radar receiver; G _T is the airborne radar transmitting antenna gain, G _R is the airborne radar receiving antenna gain; T _D is the airborne radar transmitting beam sweep point target Dwell time; L _R represents the system loss of the airborne radar, σ represents the target reflection cross-sectional area, and η represents the duty cycle of the rectangular pulse signal emitted by the airborne radar. 6. airborne radar radio frequency stealth performance evaluation method as claimed in claim 1, is characterized in that, the power Pi corresponding to intercepting the signal that receiver _receives is: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; fa</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}<span\; class="notranslate">\; \&times;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}$ Among them, L _p represents the polarization loss of the corresponding intercept receiver, R represents the distance between the airborne radar and the corresponding intercept receiver, G _TI is the antenna gain of the airborne radar in the direction of the corresponding intercept receiver, G _I is the corresponding intercept receiver receiving antenna gain; L _I is the system loss of the corresponding intercept receiver; p _d represents the target detection probability of the set airborne radar, p _fa represents the target detection false alarm probability of the set airborne radar; k ₀ represents the wave T ₀ is the noise temperature of the airborne radar receiver, F _n is the noise figure of the airborne radar receiver; G _T is the gain of the airborne radar transmitting antenna, G _R is the gain of the airborne radar receiving antenna; T _D is the residence time of the airborne radar’s transmit beam sweeping point target; L _R represents the system loss of the airborne radar, σ represents the target reflection cross-sectional area, and η represents the duty cycle of the rectangular pulse signal emitted by the airborne radar. 7. airborne radar radio frequency stealth performance evaluation method as claimed in claim 1, it is characterized in that, in step 4, when airborne radar transmits a beam, at least one intercept receiver successfully _intercepts the calculation formula of the probability p of corresponding beam for: ${\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; MF</span>}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; )</span>}^{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; OT</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}$ Among them, MF represents the main lobe coverage area when the transmission signal gain of the airborne radar is 3dB, P _I is the power required by each intercepting receiver to detect the signal, D _I refers to the density of the intercepting receiver, and T _I represents the power of each intercepting receiver. The search frame time of the receiver, T _OT represents the exposure time of the airborne radar to each intercepting receiver; C ₀ represents the coverage area/sensitivity scale factor of the set airborne radar, and P _i represents the signal received by the corresponding intercepting receiver power. 8. airborne radar radio frequency stealth performance evaluation method as claimed in claim 1, is characterized in that, in step 5, each intercepts receiver detection signal required power _PI to be: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; min</span>}}}{\mathrm{<span\; class="notranslate">\; 3.55</span>}\sqrt{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}}$ Among them, S _Imin is the sensitivity of each intercepting receiver, T _D is the dwell time of the airborne radar's transmitting beam sweeping the point target, f _r is the pulse repetition frequency of the airborne radar when it is working. 9. airborne radar radio frequency stealth performance evaluation method as claimed in claim 1, it is characterized in that, in step 5, when airborne radar transmits a beam, the probability p that at least one intercepting receiver successfully intercepts corresponding _beam is: ${\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; MF</span>}<span\; class="notranslate">\; \&times;</span>{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; fa</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; Ti</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}}{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\frac{\sqrt{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; min</span>}}}{\mathrm{<span\; class="notranslate">\; 3.55</span>}\sqrt{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span>}^{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; OT</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; I</span>}}$ Among them, MF represents the main lobe coverage area when the transmit signal gain of the airborne radar is 3dB, D _I refers to the density of intercepting receivers, T _I represents the frame time of each intercepting receiver, T _OT represents the airborne radar’s C ₀ represents the coverage area/sensitivity scale factor of the set airborne radar; L _p represents the polarization loss of the corresponding intercepting receiver, R represents the distance between the airborne radar and the corresponding intercepting receiver, G _TI is the antenna gain of the airborne radar in the direction corresponding to the intercepting receiver, G _I is the receiving antenna gain of the corresponding intercepting receiver; L _I is the system loss of the corresponding intercepting receiver; p _d represents the set target of the airborne radar Detection probability, p _fa represents the target detection false alarm probability of the set airborne radar; k ₀ represents the Boltzmann constant, T ₀ represents the noise temperature of the airborne radar receiver, F _n represents the noise of the airborne radar receiver coefficient; G _T is the gain of the airborne radar transmitting antenna, G _R is the gain of the airborne radar receiving antenna; _LR represents the system loss of the airborne radar, σ represents the target reflection cross-sectional area, and η represents the rectangular pulse signal transmitted by the airborne radar Duty cycle; S _Imin is the sensitivity of each intercepting receiver, T _D is the dwell time of the airborne radar's transmitting beam sweeping the point target, f _r is the pulse repetition frequency when the airborne radar is working.