CN101814659A - Triangular slotted waveguide array antenna - Google Patents

Abstract

A triangular waveguide slot array antenna is used in the fields of radar communication, microwave communication, and television broadcasting system communication. The triangular waveguide slot array antenna includes a section of waveguide, the cross section of the waveguide is an isosceles right triangle, the waveguide has a radiation slot on the hypotenuse wall of the isosceles right triangle, and the feeding device is an N-type coaxial connector, which is located at one end of the waveguide . The triangular waveguide slot array antenna has the characteristics of high gain, low side lobe, compact structure, and easy control of the mouth-surface distribution.

Description

A Triangular Waveguide Slot Array Antenna

technical field

The invention relates to the improvement of the shape and structure of the waveguide slot array antenna, in particular to a wide-band triangular waveguide slot array antenna. The invention can be used in the fields of radar communication, microwave communication, and television broadcasting system communication.

Background technique

Since the 1940s, the research and application of waveguide slot antennas have developed rapidly. The waveguide slot antenna was originally used in ground air defense radar, and then used in shipboard, airborne, beacon and missile-borne radar and other fields. The advantage is that the electric field amplitude and phase distribution of the array aperture can be precisely controlled, the waveguide transmission power capacity is large, the loss is small, and the requirements of high gain and low sidelobe can be easily realized. With the continuous improvement of communication technology, the waveguide slot antenna has a wider range of applications. It works in the X and Ku bands and is often used as a radar beacon antenna, and works in the S band for the transmission of multi-channel microwave distribution systems for cable TV program transmission. Antenna etc.

Using the traditional rectangular waveguide, open several pairs of longitudinal parallel slots opposite to each other on the wide side, when the slot spacing is half of the waveguide wavelength, a standing wave array is formed. This kind of waveguide slot antenna can realize the characteristics of high gain and low sidelobe. The standing wave array is a narrow-band antenna. To ensure the required bandwidth of the antenna, the number of slots on the waveguide is limited. Mazen Hamadallah analyzed this standing wave array antenna, and proposed that the more elements on a waveguide, the narrower the bandwidth (Mazen Hamadallah, Frequency Limitation on Broad-Band Performance of Shunt Slot Arrays.IEEE Transactions on Antennas and Propagation.Vol .37, No. 7, 1989, pp: 817-823). When the rectangular waveguide slot antenna deviates from the center frequency, the standing wave at the input will deteriorate, resulting in narrow bandwidth.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a waveguide slot array antenna whose cross section is an isosceles right triangle, which effectively improves the bandwidth of the traditional rectangular waveguide slot antenna.

Concrete technical scheme of the present invention is as follows:

The waveguide slot array antenna of the present invention has a section of waveguide, the cross-section of the waveguide is an isosceles right triangle, the wall surface of the hypotenuse of the isosceles right triangle of the waveguide has a slit, the two ends of the waveguide are closed, and one end is equipped with a feeder electric device.

The cross-section of the waveguide is an isosceles right-angled triangle, and the length of the right-angled side is l, as shown in FIG. 1 in the Cartesian coordinate system. The transmission of TE waves in this waveguide is different from the traditional rectangular waveguide, which is determined by the following boundary value problem:

$\left\{\begin{array}{c}<span\; class="notranslate">\; (</span>\frac{{<span\; class="notranslate">\; \&PartialD;</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; +</span>\frac{{<span\; class="notranslate">\; \&PartialD;</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{<span\; class="notranslate">\; \&PartialD;</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ \mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\frac{{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ \mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; ,</span>\frac{<span\; class="notranslate">\; \&PartialD;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ \mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\frac{<span\; class="notranslate">\; \&PartialD;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; -</span>\frac{<span\; class="notranslate">\; \&PartialD;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}}{<span\; class="notranslate">\; \&PartialD;</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.$

The TE mode of the isosceles right-angled triangular waveguide can be obtained by the superposition of the waveguide whose cross-section is a square and the side length is 1, and the TE wave solution in the waveguide is:

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; cos</span>}\frac{\mathrm{<span\; class="notranslate">\; m\&pi;</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\frac{\mathrm{<span\; class="notranslate">\; n\&pi;</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; cos</span>}\frac{\mathrm{<span\; class="notranslate">\; n\&pi;</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}\mathrm{<span\; class="notranslate">\; x</span>}\mathrm{<span\; class="notranslate">\; cos</span>}\frac{\mathrm{<span\; class="notranslate">\; m\&pi;</span>}}{\mathrm{<span\; class="notranslate">\; l</span>}}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&omega;t</span>}<span\; class="notranslate">\; )</span>}$

in, $k_z=\sqrt{{\left(\frac{\mathrm{\&omega;}}{c}\right)}^2-{\left(\frac{\mathrm{m\&pi;}}{l}\right)}^2-{\left(\frac{\mathrm{n\&pi;}}{l}\right)}^2},$ The cutoff frequency is $f_c=\frac{c}{2\mathrm{<figure-callout\; id="2"\; label="l\; m"\; filenames="H2009102283837E00021.png,H2009102283837E00022.png"\; state="\{\{state\}\}">l</figure-callout>}}\sqrt{m^{}}\sqrt{{}^2+{\mathrm{<figure-callout\; id="2"\; label="no"\; filenames="H2009102283837E00021.png,H2009102283837E00022.png"\; state="\{\{state\}\}">no</figure-callout>}}^2},$ c is the speed of light, and the cut-off frequency f _c of the TE ₁₀ mode is:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; l</span>}}$

The cut-off wavelength λ _c of TE ₁₀ mode is:

λ _c =2l

The waveguide wavelength λ _g of the isosceles right triangle waveguide can be obtained from the formula of the waveguide wavelength as:

${\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}}{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}$

Among them, λ is the central working wavelength, and f is the central working frequency.

The slots of the waveguide slot antenna must cut the inner wall current to excite the antenna to radiate electromagnetic waves, and the distance between the centers of the slots of the waveguide slot antenna is λ _g /2. In order to ensure that only TE ₁₀ waves are transmitted in the waveguide, the right-angled side l of the isosceles right-angled triangle waveguide should satisfy λ/2<l<λ. If the central operating frequency of the antenna is determined, the size range of the cross-section of the waveguide can be determined.

Compared with the prior art, the present invention has the following prominent substantive features and significant advantages:

1. The cross-section of the waveguide is an isosceles right triangle. Through simulation and experimental verification, as the number of slots increases, the gain of the antenna increases; as the number of slots increases, the bandwidth of the antenna also increases.

2. The feeder adopts N-type coaxial connector, which has a simple structure and saves cost.

3. The distance between the shaft center of the N-type coaxial connector and the closed end is λ _g /4, and the length can be fine-tuned. The distance between the shaft center of the N-type coaxial connector and the center of the first gap The distance between the gaps is adjustable as an integer multiple of λ _g /2, the distance between the last gap and the closed end is adjustable as an integer multiple of λ _g /4, and the insertion depth of the coaxial probe of the N-type coaxial connector is adjustable, so that A good match is achieved near the operating frequency of the antenna center, and the characteristics of high gain and low side lobe are realized.

Description of drawings

Figure 1 is a cross-sectional view of an isosceles right triangle waveguide.

Figure 2 is the effect diagram of the overall appearance of the antenna.

Figure 3 is a top view of the antenna.

FIG. 4 is a cross-sectional view along line B-B of FIG. 3 .

FIG. 5 is a cross-sectional view along line A-A of FIG. 3 .

Fig. 6 is a gain comparison result of the 10-slot X-band triangular waveguide slot array antenna of the present invention and the 10-slot traditional rectangular waveguide slot antenna.

Fig. 7 is the VSWR comparison result of the 10-slot X-band triangular waveguide slot array antenna of the present invention and the 10-slot traditional rectangular waveguide slot antenna.

In the figure: 1a-the hypotenuse wall of an isosceles right triangle, 1b-the right side wall of an isosceles right triangle, 1c-closed end, 1d-closed end, 2-radiating gap, 3a-coaxial feeder shell, 3b-coaxial axis probe.

Detailed ways

Below in conjunction with accompanying drawing, the present invention will be further described through embodiment.

Example 1:

Referring to Fig. 2, Fig. 3, Fig. 4 and Fig. 5, a preferred embodiment is a uniformly distributed 10-slot isosceles triangular waveguide slot array antenna working in the X-band. This embodiment can be applied to other wavebands, that is, to change the length of the right-angled side of the isosceles right-angled triangle of the radiation waveguide section, such as for S-band and C-band. As shown in Figure 2, the array antenna consists of a radiation waveguide, including an isosceles right-angled triangle hypotenuse wall 1a, an isosceles right-angled triangle right-angled side wall 1b, closed ends 1c and 1d, a radiation slot 2 and a coaxial feeder.

The radiation waveguide is a metal waveguide whose cross-section is an isosceles right triangle, and it can also be made of a copper-clad dielectric plate, and the two ends are respectively closed. The length W ₁ of the right-angled side is 22.86mm, the wall thickness W ₂ is 1.27mm, and the length of the radiation waveguide is 220mm.

As shown in Fig. 2 and Fig. 3, 10 radiating slits 2 are alternately located on both sides of the midline of the hypotenuse wall 1a of an isosceles right triangle, and the radiating slits 2 are longitudinal rectangular long slits or round-ended rectangular long slits. The length of the radiation slot 2 is approximately equal to λ/2, and the preferred size in this embodiment is 0.49λ. The slit width is much smaller than the slit length, and the preferred size in this embodiment is 0.033λ. The distance L ₂ between the radiation gaps must satisfy the condition of λ _g /2, which can be calculated by the above calculation formula. The offset distance h of the gap is determined by requirements such as voltage standing wave ratio, and the preferred size in this embodiment is 0.1λ. The distance L ₁ between the last slit and the closed end 1c is adjustable as an integral multiple of λ _g /4, which is preferably λ _g /4 in this embodiment.

The signal input and output ports of the array antenna are coaxial feeders, located on the center line of the hypotenuse wall 1a of the isosceles right triangle. This embodiment is preferably a 50 ohm N-type coaxial connector, as shown in FIG. 3 , FIG. 4 and FIG. 5 , 3 a is the coaxial power feeding device housing, and 3 b is the coaxial probe. The distance L ₃ between the axis center of the coaxial feeder and the center of the first slit is adjustable as an integral multiple of λ _g /2, and is preferably λ _g /2 in this embodiment. The distance L ₄ between the last slit and the closed end 1d is λ _g /4, and the length can be fine-tuned. In this embodiment, it is preferably λ _g /4. The insertion depth of the coaxial probe 3b is adjustable, which is 8mm in this embodiment.

Fig. 6 is the gain comparison result of the 10-slot X-band triangular waveguide slot array antenna embodiment of the present invention and the 10-slit traditional rectangular waveguide slot antenna. Compared with the rectangular waveguide slot antenna, the triangular waveguide slot array antenna has basically the same gain, and the triangular waveguide slot The first sidelobe level of the array antenna is low.

Fig. 7 is the VSWR comparison result of the 10-slit X-band triangular waveguide slot array antenna embodiment of the present invention and the 10-slot traditional rectangular waveguide slot antenna, the VSWR ratio of the triangular waveguide slot array antenna compared with the rectangular waveguide slot antenna With an operating bandwidth of less than 2, the triangular waveguide slot array antenna increases by 440MHz compared to the rectangular waveguide slot antenna.

Another embodiment of the present invention is different from that of embodiment 1 in that the type of radiation slit is a round hole, and the others are the same as embodiment 1.

In yet another embodiment of the present invention, it is different from that in embodiment 1 in that the type of radiation slit is X type, and the others are the same as in embodiment 1.

In yet another embodiment of the present invention, the arrangement and installation of the triangular waveguide slot array antennas in all the above-mentioned embodiments can also form an antenna array. The wall surface 1a faces upward; or several triangular waveguide slot array antennas surround in three dimensions, and the right-angled edges of the radiation waveguides face each other.

In addition, on the basis of this embodiment, increasing or decreasing the number of slots, and adjusting matching and feeding circuits accordingly should all be regarded as the protection scope of the invention determined by the submitted claims.

Claims (6)

1. A triangular waveguide slot array antenna comprises a waveguide section, slots are arranged on the wall surface of the waveguide section, two ends of the waveguide section are closed, and a feed device is arranged at one end of the waveguide section, and the triangular waveguide slot array antenna is characterized by comprising: the cross section of the waveguide is an isosceles right triangle, a radiation gap is formed in the wall surface of the hypotenuse of the waveguide, and the feed device is an N-type coaxial connector and is located at one end of the waveguide.

2. The triangular waveguide slot array antenna of claim 1, comprising: the radiation slots are longitudinally and parallelly arranged on two sides of the central line of the bevel edge wall surface of the isosceles right triangle of the radiation waveguide, and the distance between the centers of the radiation slots is half of the waveguide wavelength.

3. The triangular waveguide slot array antenna of claim 1, comprising: the shape of the radiation gap is a longitudinal rectangular long seam or a round-head rectangular long seam.

4. The triangular waveguide slot array antenna of claim 1, comprising: the radiation gap is in a round hole shape.

5. The triangular waveguide slot array antenna of claim 1, comprising: the radiation slit is X-shaped.

6. The triangular waveguide slot array antenna of claim 1, comprising: the distance between the axis and the closed end of the N-type coaxial connector is one-fourth of the waveguide wavelength, the length can be finely adjusted, the distance between the axis and the center of the first gap of the N-type coaxial connector is adjustable by one-half of the waveguide wavelength, the distance between the center of the last gap and the closed end is adjustable by one-fourth of the waveguide wavelength, and the insertion depth of the coaxial probe of the N-type coaxial connector is adjustable.

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