CN102769212A - An intermediate frequency analog RoF phase-controlled active integrated antenna - Google Patents

Abstract

The invention discloses a medium-frequency simulated RoF (radio over fiber) type phase control active integrated antenna, which comprises a simulated light module, a medium-frequency transceiver module, radio transceiver modules and antenna units, wherein the simulated light module connected with a near-end machine is connected with the radio transceiver modules through the medium-frequency transceiver module; and each radio transceiver module is connected with one antenna unit. Different from the conventional array antenna, the medium-frequency simulated RoF type phase control active integrated antenna has the characteristics that each antenna unit in the active integrated antenna array is directly connected with one complete radio transceiver module, and a signal of each unit is subjected to power distribution/combination on the medium frequency, passes through the medium-frequency transceiver module and is connected with the light module and finally converted into a light signal through the light module for long-distance low-loss transmission; and the phase of the radio transceiver module behind each antenna unit is controllable, so that the wave beam of the whole array can be scanned in the perpendicular direction.

Description

An intermediate frequency analog RoF phase-controlled active integrated antenna

technical field

The invention relates to an active antenna, in particular to an intermediate frequency analog RoF phase-controlled active integrated antenna.

Background technique

Antennas are one of the key components of various wireless communication systems. The main technical indicators to measure their pros and cons are: impedance bandwidth, beam width, sidelobe level, gain and efficiency, etc. The conductor loss, dielectric loss of the antenna radiating unit, the insertion loss of the feeding network and the loss of the feeder will greatly reduce the efficiency of the entire system, resulting in a considerable proportion of the transmitter power being dissipated by the antenna and the feeder, and seriously affecting the receiving sensitivity. Therefore, high efficiency and intelligence have become the research goals of the next generation of wireless communication antennas.

A traditional cellular mobile communication base station is mainly composed of an antenna, a feeder cable and a radio frequency transceiver. The antenna on the top of the tower is connected to the transceiver below through a certain length of feeder cable. For the downlink, the output power of the RF transmitter is fed into the antenna installed on the top of the tower through the feeder cable and transmitted into the air; for the uplink, the mobile phone signal is received by the base station antenna on the top of the tower and enters the RF receiver under the tower through the feeder cable . Most traditional base station antennas use directional antennas with sectoral radiation patterns. The beamwidth in the horizontal plane is generally 120 degrees (10dB beamwidth), and the gain is generally about 14.5dBi. Such an antenna generally consists of an array of 8 to 12 elements in the vertical direction. The conductor loss, dielectric loss of the antenna radiating unit, the insertion loss of the feed network and the loss of the feeder will greatly reduce the efficiency of the antenna feeder system, resulting in a considerable proportion of the transmitter power being dissipated by the antenna and the feeder, and seriously affecting the receiving sensitivity . The antenna efficiency does not take into account the loss of the feeder cable. Obviously, for the above-mentioned base stations, it is more suitable to describe and

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; AF</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}$

Analyze the performance of wireless communication systems. To this end, we define the antenna feed efficiency as follows

In the formula, E _AF represents the efficiency of antenna feeder (Effciency of Antenna and Feeding Cable), P _e refers to the effective radiation power actually radiated into the air, and P _t refers to the output power of the RF transmitter.

For traditional base stations and base station sector antennas, the feeder length can usually reach tens of meters, and the loss can reach 3dB or even greater; the loss of the feed network inside the sector antenna is usually about 1~2dB. In contrast, the conductor loss, dielectric loss and reflection loss of the radiating unit are much smaller when they are well matched. Therefore, less than half of the power output from the radio frequency transmitter is radiated, that is, the antenna feed efficiency E _AF <50% at this time. We know that if the output power of an RF transmitter is doubled while maintaining linearity, its cost will increase by 0.8 to 1 times, and its DC power consumption will increase by 1 to 1.2 times.

In order to solve this problem, people began to use a large number of tower top radio frequency technologies in practical applications, that is, placing part of the radio frequency or the entire radio frequency subsystem near the tower top antenna, so that the feeder cable can be compressed to about 1m, and the loss can be reduced to less than 1dB ( including splice loss). After adopting this technology, it is obvious that the loss of the antenna feed system can be reduced to below 3dB, so that the efficiency of the antenna feed can reach 50% to 70%.

Recently, the active integrated antenna has become a research hotspot. The basic idea is to remove all the feeder cables and integrate part or the entire radio frequency subsystem with the antenna. Considering that the feed network of the antenna array still exists, the efficiency of the antenna feed can be increased to about 80% after adopting the active integrated antenna technology.

In addition to efficiency, it is often required in practice that the downtilt angle of the antenna pattern of the base station can be adjusted electrically. It is also desirable that the pattern be shapeable in the vertical plane and scannable in the horizontal plane.

Therefore, it is extremely urgent to research and realize new antenna technologies with high efficiency, steerable beam, low power consumption, low cost and various excellent characteristics supporting RoF (Radioover Fiber).

Contents of the invention

Purpose of the invention: The purpose of the invention is to design an active integrated antenna with high efficiency and energy saving, so that its beam can be steered in the vertical plane and it supports RoF.

Technical solution: In order to solve the above technical problems, the present invention adopts the following technical solutions:

An intermediate frequency analog RoF phase-controlled active integrated antenna array, which includes an analog optical module, an intermediate frequency transceiver module, a radio frequency transceiver module and an antenna unit; Each radio frequency transceiver module is connected with an antenna unit.

Wherein, the intermediate frequency transceiver module includes a transmitting module connected to the analog optical module, and the transmitting module is connected to the intermediate frequency power splitter; the intermediate frequency transceiver module also includes a receiving module connected to the analog optical module, and the receiving module is connected to the intermediate frequency combiner; The output end of the intermediate frequency power divider is connected to the feed port of the antenna unit through the radio frequency transceiver module; the feed port of the antenna unit is also connected to the input end of the intermediate frequency combiner through the radio frequency transceiver module.

Wherein, the radio frequency transceiver module includes a No. 1 mixer, a No. 1 phase shifter, an amplifier and a radio frequency switch connected to the intermediate frequency power divider in turn, and the other end of the radio frequency switch is connected to the feed port of the antenna unit; the antenna unit The feed port of the power supply is also connected to the radio frequency receiving module, the second phase shifter, and the second mixer in sequence through the radio frequency switch, and the second mixer is connected to the intermediate frequency combiner.

The intermediate frequency analog RoF phase-controlled active integrated antenna of the present invention includes an antenna unit, a radio frequency transceiver, a phase shifter, a mixer, an intermediate frequency transceiver, and an optical module, wherein the intermediate frequency transceiver module includes an intermediate frequency power splitter/combiner and Amplifying circuit part; different from traditional array antennas, each antenna unit in the active integrated antenna array of the present invention is directly connected to a complete radio frequency transceiver module, and the signals of each unit are divided/combined on the intermediate frequency After passing through the intermediate frequency transceiver module, it is connected with the optical module. Finally, the signal can be converted into an optical signal by the optical module for long-distance low-loss transmission. The phase of the RF transceiver module behind each antenna unit is controllable, so that the beam of the entire array can be scanned in the vertical direction.

Beneficial effect: the present invention has the following advantages:

1:) It has high antenna feed efficiency, which can reach 80% to 90%. After adopting the design of active integrated antenna array, the radiation

The frequency transceiver module is directly connected to the antenna unit through the connector, which avoids the loss caused by the feeder cable in the traditional RRU+passive antenna array solution, and because the power splitting/combining network is completed at the intermediate frequency, compared with the passive antenna array The RF power splitting/combining network will further reduce the loss, the overall loss can be controlled within 1dB, and the antenna feed efficiency of the system can reach 80% to 90%.

2:) The beam in the vertical plane can be scanned, and the beam can point to any direction within the range of ±40°. The shot of this program

Compared with the traditional RRU, the frequency transceiver module adds a high-precision and low-loss digitally controlled phase shifter to each channel. Through the control of the phase shifter, the phase of each unit in the antenna array can be set, and the phase of each antenna unit Setting an appropriate value can control the beam of the entire antenna array to point to the required direction, so as to realize the beam scanning of the array beam in the vertical plane.

3) Thanks to the controllable beam pointing of the antenna array, when one or several channels in the antenna array fail, the phase of the remaining channels can be adjusted to adjust the radiation beam pointing of the antenna array, which can compensate for the failure of the channel. The change of the radiation direction of the incoming antenna enhances the stability of the system to a certain extent.

4) The intermediate frequency is used to simulate RoF, which can perform low-loss transmission and facilitate networking.

Description of drawings

Fig. 1 is the structure schematic diagram of intermediate frequency analog RoF type phase control active integrated antenna of the present invention,

Fig. 2 is the beam scanning of the antenna of the present invention working in the transmitting state (at intervals of 10°)

Fig. 3 is the beam scanning of the antenna of the present invention working in the receiving state (at intervals of 10°)

Detailed ways:

The present invention will be further explained below in conjunction with the accompanying drawings.

As shown in Figure 1, a kind of intermediate frequency analog RoF type phase control active integrated antenna array of the present invention comprises analog optical module 1, intermediate frequency transceiver module 2, radio frequency transceiver module 3 and antenna unit 4; The analog optical module 1 is connected to several radio frequency transceiver modules 3 through an intermediate frequency transceiver module 2 , and each radio frequency transceiver module 3 is connected to an antenna unit 4 . The power supply supplies power to the entire intermediate frequency analog ROF phase-controlled active integrated antenna, and the analog optical module 1 is connected to the analog optical module of the near-end device through an optical fiber.

The role of the analog optical module 1 is photoelectric conversion. The transmitting end converts the electrical signal into an optical signal; after being transmitted through the optical fiber, the receiving end converts the optical signal into an electrical signal.

The transmitting module 21 in the intermediate frequency transceiver module 2 amplifies the intermediate frequency signal transmitted from the analog optical module 1, and then passes it to each radio frequency transmission channel through the intermediate frequency power divider 22; the intermediate frequency combiner phase 24 of the intermediate frequency receiving module 2 receives the signal from For signals sent from each channel of the radio frequency transceiver module 3 , the intermediate frequency combiner 24 synthesizes each signal into one signal, which is then amplified by the receiving module 23 and then transmitted to the analog optical module 1 .

The radio frequency transceiver module 3 is the core part of the active integrated antenna array. The transmitting part up-converts the intermediate frequency signal transmitted by the intermediate frequency power divider 22 to the radio frequency frequency, performs filtering, phase shifting and amplification, and then transmits it to the antenna unit 4; The receiving module 37 filters and amplifies the weak signal transmitted by the antenna unit 4 , and down-converts the signal to an intermediate frequency, and then the signals of each channel are combined in the intermediate frequency combiner 24 .

The antenna unit 4 is an energy conversion device, which converts the signal generated by the radio frequency transmitting module 3 into electromagnetic waves and transmits them to the space, and collects the electromagnetic waves in the space and converts them into radio frequency signals and transmits them to the radio frequency receiving module 3 .

Wherein, the intermediate frequency transceiver module 2 includes a transmitting module 21 connected to the analog optical module 1, and the transmitting module 21 is connected to the intermediate frequency power divider 22; the intermediate frequency transceiver module 2 also includes a receiving module 23 connected to the analog optical module 1, receiving The module 23 is connected with the intermediate frequency combiner 24 .

Described radio frequency transceiver module 3 comprises No. 1 mixer 31, No. 1 phase shifter 32, amplifier 33, radio frequency switch 34 that are connected to intermediate frequency power divider 22 successively; The electrical port is connected; the feed port of the antenna unit 4 is also connected to the radio frequency receiving module 37, the second phase shifter 36, and the second mixer 35 through the radio frequency switch 34, and the second mixer 35 is connected to the intermediate frequency combiner 24 . No. 1 mixer 31, No. 1 phase shifter 32, amplifier 33, radio frequency switch 34 have formed the transmitting part of radio frequency transceiver module 3, No. 2 mixer 35, No. 2 phase shifter 36, radio frequency receiving module 37 and radio frequency The switch 34 constitutes the receiving part of the radio frequency transceiver module 3 . Wherein, the radio frequency switch 37 can be a common switch or a duplexer, and the radio frequency receiving module 37 includes a filter circuit and an amplifier connected to the radio frequency switch 34 in sequence.

The output end of the intermediate frequency power divider 22 is connected to the feed port of the antenna unit 4 through the radio frequency transceiver module 3; the feed port of the antenna unit 4 is connected to the input end of the intermediate frequency combiner 24 through the radio frequency transceiver module 3.

The radio frequency transceiver module 3 can control the phase of each channel in the antenna array through the phase shifter. Setting the phase of each channel at a suitable value can control the beam of the entire antenna array to point to the desired direction, thereby realizing beam scanning in the vertical plane .

Each antenna unit 4 of the present invention is directly connected to an independent radio frequency transceiver module 3. Compared with the traditional RRU (radio remote module) + passive antenna array, it can ensure the EIRP (effective omnidirectional) of the entire antenna array Radiation power) under the same conditions, the RF output power required by a single RF transmitting module in this solution is only 1/N of the output power of the power amplifier in the traditional RRU solution (N is the number of antenna arrays, generally 8-12), so Small and medium-sized power amplifiers can be used to replace high-power amplifiers in ordinary RRU solutions, which reduces the system’s heat dissipation requirements, and can further reduce system cost and circuit area; The requirement on the power capacity of the duplexer can be reduced, and the cost and volume of the system can be further reduced.

Compared with the traditional RRU, each channel of the radio frequency transceiver module of the present invention adds a digitally controlled phase shifter, through the control of the phase shifter, the phase of each unit in the antenna array can be set, and the phase of each antenna unit can be set to When the value is appropriate, the beam of the entire antenna array can be controlled to point to the required direction, so as to realize the beam scanning of the array beam in the vertical plane.

The phase of the radio frequency transceiver module 3 of the intermediate frequency analog RoF type phased active integrated antenna of the present invention can be controlled, and by setting a specific phase, the beam of the array in the vertical plane can be directed to a required angle to realize the function of beam scanning. The radio frequency transceiver module 3 is directly connected to the antenna unit 4 through a connector, which reduces the loss of the feeder line and the feeder network, and improves the efficiency of the antenna feeder.

The following will be further described in conjunction with an embodiment of the antenna of the present invention. The antenna of this embodiment is an intermediate frequency analog RoF type phase-controlled active integrated antenna. Its radio frequency operating frequency range is 2.3GHz to 2.4GHz. For switching, the intermediate frequency ranges from 1GHz to 1.1GHz, and the array is a uniformly distributed linear array of 8 units. The maximum transmit power of each radio frequency unit is 21dBm, the gain of the antenna unit is 7dB, and the maximum EIRP of the entire array is 45.5dBm (0.5dB loss ). The radiation beam of the array has a 3dB beamwidth of 10° in the vertical plane and can be directed at any angle within the range of ±40°.

Fig. 2 and Fig. 3 are the beam scanning results of the antenna of the present invention, with 10 ° as the interval during measurement, it can actually point to any angle, as can be seen from the test results, the beam scanning under the transmitting and receiving states can be in the range of ±40 ° Point to exactly the desired location.

Figures 2 and 3 show the beam scanning results of the active antenna of the embodiment in the transmitting and receiving states. It can be seen from the results that the beam of the active integrated antenna array can be adjusted in the vertical plane according to the needs of the system. When the antenna of this embodiment is used as a base station antenna system for mobile communications, the direction of the beam can be adjusted in time according to business needs to obtain optimal coverage; and thanks to the controllable characteristics of the beam direction of the antenna array, when the antenna array of this embodiment When one or several channels fail, the phase of the remaining channels can be adjusted to adjust the beam direction of the antenna array to compensate for the change of the antenna radiation direction caused by the channel failure, which enhances the stability of the system to a certain extent.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (3)

1. An intermediate frequency analog RoF phase-controlled active integrated antenna array, characterized in that it includes an analog optical module (1), an intermediate frequency transceiver module (2), a radio frequency transceiver module (3) and an antenna unit (4); The analog optical module (1) connected to the near-end unit is connected to several radio frequency transceiver modules (3) through the intermediate frequency transceiver module (2), and each radio frequency transceiver module (3) is connected to an antenna unit (4). 2. An intermediate frequency analog RoF phase-controlled active integrated antenna array according to claim 1, characterized in that: the intermediate frequency transceiver module (2) includes a transmitting module connected to the analog optical module (1) ( 21), the transmitting module (21) is connected to the intermediate frequency power divider (22); the intermediate frequency transceiver module (2) also includes a receiving module (23) connected to the analog optical module (1), and the receiving module (23) is combined with the intermediate frequency Device phase (24) even; The output end of the intermediate frequency power divider (22) is connected to the feed port of the antenna unit (4) through the radio frequency transceiver module (3); the feed port of the antenna unit (4) is also connected through the radio frequency transceiver module ( 3) Connect with the input terminal of the intermediate frequency combiner (24). 3. An intermediate frequency analog RoF phase-controlled active integrated antenna array according to claim 2, characterized in that: the radio frequency transceiver module (3) includes a power divider (22) connected to the intermediate frequency in turn No. 1 mixer (31), No. 1 phase shifter (32), amplifier (33) and radio frequency switch (34), the other end of the radio frequency switch (34) is connected with the feeding port of the antenna unit (4); the antenna unit The feed port of (4) is also connected to the radio frequency receiving module (37), the second phase shifter (36), the second mixer (35) through the radio frequency switch (34), and the second mixer (35) and The intermediate frequency combiner (24) is connected.

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