CN102136634A - Ku/Ka frequency band circularly polarization integrated receiving and transmitting feed source antenna - Google Patents

Abstract

The invention provides a Ku/Ka frequency band circularly polarization integrated receiving and transmitting feed source antenna applied to antenna systems, such as a paraboloid antenna and the like, in satellite communication. The antenna adopts a coaxial nested compact structure, and is applied to Ku frequency band and Ka frequency band at the same time. The basic structure of a feed source comprises a circular waveguide, on which a pointed cone shaped dielectric rod is loaded, a flange, a coaxial waveguide, a symmetrical SMA connector pair, a circular polarizer and an orthogonal mode coupler, wherein the feed source in the Ka frequency band is applied to dual circular polarization, has rotary symmetrical radiation directional diagrams, the circularly polarization axial ratio in Ka double band is smaller than minus 2dB, and the transmitter-receiver isolation is smaller than minus 70dB; and the feed source in the Ku frequency band is applied to dual circular polarization, has rotary symmetrical radiation directional diagrams, a cross polarization level smaller than minus 40dB, and good transmitter-receiver isolation and reflection loss.

Description

A Ku/Ka band line circularly polarized integrated transceiver-feed antenna

technical field

The invention belongs to the technical field of feed source design in wireless communication, and particularly relates to technologies such as Ku/Ka frequency band transceiver four-band, linear circular polarization integration and other technologies in feed source design in satellite communication system.

Background technique

With the development of satellite communications, the existing C-band satellite resources can no longer meet the growing demand for satellite communications, so it is imperative to develop Ku and Ka bands. The vigorous development of the satellite communication industry puts forward new requirements for its ground station antennas, such as high gain, broadband or multi-band, low cross-polarization, multi-beam, multi-polarization and so on.

The feed is the heart of the entire antenna system, and a high-performance feed is the first condition for a high-performance antenna system. How to design Ku and Ka frequency bands to work in broadband or multi-bands at the same time, with the characteristics of low cross-polarization and high isolation, and can realize dual-polarized or multi-polarized feeds for sending and receiving, so as to better meet Lunberg lens Feed requirements for antennas, parabolic antennas and other antenna systems.

The high-efficiency and compact Ku/Ka corrugated horn feed can effectively use the same radiation port surface, so that the antenna can work in four different frequency bands at the same time, and the utilization rate of the antenna is increased by three times. When the corrugated horn feed antenna is fed, signals of four different frequency bands and four different polarizations can be transmitted simultaneously. That is to say, within these four frequency bands, the antenna can transmit two signals at the same time and receive two signals at the same time. The interference between the signals can be solved by high isolation between transceivers and polarization separation.

Du Biao and others from the 54th Research Institute of China Electronics Technology Group Corporation disclosed a dual-slot structure dual-band shared corrugated horn feed in the patent CN1438733. The converter, the double groove deep corrugated structure frequency change, the angle change transition section and the double groove deep corrugated structure radiation section are composed. It is suitable as the feed source for dual-band shared satellite communication and measurement and control antennas such as L/C, S/C, S/X and C/Ku. In the patent CN1317884, Yang Kezhong and others disclosed a corrugated horn feed source for improving the cross-polarization characteristics of the biased parabolic antenna. It consists of a dual-mode corrugated horn and a circular waveguide, a coupling cavity, and a coupling hole that are propagated by a high-order mode and cut off. composed of exciters. It is especially suitable for the satellite communication single offset parabolic antenna with small focal length diameter ratio in the Ku frequency band as the feed device. Wan Xiaomei and others from the 38th Research Institute of China Electronics Technology Group Corporation disclosed a dual circular polarization and differential beam broadband Corrugated horn feed antenna, its structure includes an antenna body and a coaxial probe, the antenna body is cylindrical, the upper part is a corrugated part, and the lower part is a feeding part. Broadband dual-polarization single-pulse feed that can be used in high frequency bands can achieve good circular polarization axis ratio within 60% of the frequency band. Tang Yimin and others from the 29th Institute of Electronics of the Ministry of Information Industry disclosed a broadband, high-power, high-isolation orthogonally polarized feed source in Patent No. CN1331502. While the orthogonally polarized feed meets the requirement of wide frequency band and high power capacity, the isolation between the main channel and the side channel has been qualitatively improved, reaching more than 42dB. The patents on the feed disclosed above are generally dual-band designs, some of which meet the requirements of high power, and some of which meet the requirements of broadband or high isolation to achieve effective radiation characteristics of the antenna system. However, the feed source of the present invention works in the Ku and Ka frequency bands, and can simultaneously transmit and receive circularly polarized lines. In the antenna system, multiple feed sources are not required to cover four frequency bands alone, and the problem of beam distortion when multiple feed sources are placed is solved. Defocus problem. At the same time, the feed has excellent radiation characteristics and high isolation when working in the Ku-band and Ka-band transceivers.

American professional inventor Joseph A. Preiss, in the published patent No. 6005528 titled "Dual Band Feed with Integrated Mode Transducer", described a feed structure that is loaded by an intermediate dielectric rod, and the periphery is nested with corrugated horns with axial grooves , to achieve radiation characteristics in two frequency bands, but due to the high requirements on the process of axial slotting, the processing cost is relatively high. In 2006, Stephen D. Tafgonski published "A Multiband Antenna for Satellite Communications on the Move" in IEEE Transactions on Antennas and Propagation, October 2006, Vol.54, No.10, p.2862-2868. A three-band feed is introduced, which operates at 20.2-21.2GHz (K band), 30-31GHz (Ka band), and 43.5-45.5GHz (Q band). The advantage of this feed is that it can work in three frequency bands and multiple polarizations at the same time, and it can ensure high aperture efficiency. American patent inventor Robert A. Frosch introduced a feed source working in five frequency bands in the published patent No. 4258366 titled "Multifrequency Broadband Polarized Horn Antenna". The mode structure couples signals out of a common transmission waveguide. Since the signals of multiple frequency bands are transmitted together, the feed needs many bandpass filters at the output interface to separate each signal and increase the isolation between frequency bands. The far-field pattern of its radiation in each frequency band is less equal. In 2009, Bhattacharyya, A. et al. published a paper titled "Multiband Feed using coaxial configuration" on Antennas and Propagation Society International Symposium, 2009.APSURSI'09.IEEE, discussing a coaxial nested structure to achieve work in S, Ku, K, Ka frequency band schemes. The circular waveguide with variable tension angle in the middle of the feed propagates electromagnetic wave signals in the Ku, K, and Ka frequency bands, while the coaxial waveguide with stepped variable tension angle propagates the signal in the S frequency band. At high frequencies, various couplings between the coaxial waveguide and the circular waveguide have a significant effect on the performance of the feed. The article mentions the use of a circular waveguide to realize the effective radiation of the three frequency bands, but does not mention the isolation between signals of each frequency band in the feed network later. It is not satisfied to carry out the sending and receiving work at the same time as required by us.

Compared with the invention patents and papers mentioned above, the coaxial nested structure of the linear circular polarization integrated four-band feed source adopted by the present invention ensures the isolation between adjacent frequency bands, and enables the feed source to Frequency band, Ka dual-band transmit and receive work at the same time, without additional filters to separate the transmit and receive signals. The far-field radiation pattern of the feed source is axially symmetrical, with low cross-polarization, good linear circular polarization performance and return loss. In the traditional Lunberg lens feed system, single Ku or Ka feeds are placed side by side, and the maximum beam pointing will have a certain angle of deviation, which makes it impossible to receive the same satellite. This feed solves the problem of beam defocus It is especially suitable for the feed system of large satellite communication antennas such as parabolic antennas.

Contents of the invention

The purpose of the present invention is to provide a circular dual-polarized, four-band high-efficiency and compact feed source for large-scale antenna systems such as parabolic antennas in satellite communications. It works in the Ku/Ka band and has a rotationally symmetrical radiation direction Figure, extremely low cross polarization, good return loss and high isolation and other excellent performance, and compact structure, strong practicability.

The linear circularly polarized four-band Ku/Ka feed source invented in this paper adopts a coaxial nested structure, so that the radiation ports of the Ku and Ka feed sources can be separated in space. It consists of a flange plate 1, a tapered dielectric rod 2, an internal circular waveguide 3, a pair of SMA connectors for the Ku feed source emission 4, a symmetrical metal short-circuit column 5, a Ku feed source receiving orthogonal mode pair 6, and a Ka feed source receiving pair Port 7, Ka feed source launch port 8, coaxial waveguide 9, circular polarizer 10, stepped waveguide 11. Among them, Ku feed source transmitting SMA connector pair 4 adopts 50 ohm SMA connectors often used in microwave communication, Ku feed source receiving orthogonal mode pair 6 is externally connected to national standard rectangular waveguide BJ140, Ka feed source receiving port 7 is externally connected to BJ220, Ka feed source The launch port 8 is externally connected to the BJ320, and the symmetrical metal reflection column 5 is fixed in the coaxial waveguide 9 by welding or drilling.

The Ku/Ka feed source invented in this paper works in the Ku and Ka bands, the Ku feed source transmits the SMA connector pair 4 for the transmit frequency band f _T (bandwidth 5%), and the Ku feed source receives the orthogonal mode pair 6 for the receive frequency band f _R (bandwidth 5%). Adjust the position of the transmitting SMA connector pair 4, the receiving orthogonal mode pair 6, the symmetrical metal shorting post 5 in the coaxial waveguide 9, and the depth that the transmitting SMA connector pair 4 penetrates into the coaxial waveguide 9 , the relative position of the circular waveguide 3 and the coaxial waveguide 9 on the radiation port surface and the size of the stepped waveguide 11 of the coaxial waveguide 9 on the feed source radiation port surface, the Ku/Ka feed source described in this paper has obtained good return loss and transceiver isolation. Among them, the symmetrical metal short-circuit column 5 plays the role of reducing the length of the feed source and improving the isolation between sending and receiving.

The tapered dielectric rod 2 adjusts the main mode TE ₁₁ mode propagating in the inner circular waveguide 3 to the HE ₁₁ mode, and the HE ₁₁ mode can obtain a rotationally symmetric radiation pattern. In order to ensure that no modes other than the HE ₁₁ mode are excited, the inner radius r of the circular waveguide 4 and the relative permittivity ε _r of the tapered dielectric rod 1 and the operating wavelength λ need to satisfy the following formula:

$\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; <</span>\frac{\mathrm{<span\; class="notranslate">\; 1.22</span>}}{\sqrt{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}\mathrm{<span\; class="notranslate">\; \&lambda;</span>}$

In the Ka feed source, the circular polarizer 10 is a key component for realizing polarization change in the circularly polarized antenna system. The main mode TE ₁₁ mode in the circular waveguide is decomposed into two orthogonal main mode signals with equal amplitude and 90° phase difference after passing through the circular polarizer, thus constituting the circularly polarized signal transmission. The circular waveguide radiates out, and a circularly polarized radiation signal is obtained. The orthogonal mode coupler is a dual-band narrowband orthogonal mode coupler, which transmits signals in two frequency bands into the same waveguide through the orthogonal mode coupler. As shown in Figure 3, the transmission signal is fed into the waveguide through the dual-band orthogonal mode coupler, and then transformed into a circularly polarized signal through the dual-band circular polarizer, and then radiated out by the dual-frequency radiation port; the dual-frequency radiation The circularly polarized signal received by the interface becomes a linearly polarized signal through a dual-frequency circular polarizer, and then is coupled out from the standard waveguide port through a dual-band orthogonal mode coupler. The system block diagram of the dual-band circularly polarized Ka feed is shown in Figure 11.

The Ku dual-band linearly polarized feed (as shown in Figure 2) transmits vertically polarized signals and receives horizontally polarized signals in the coaxial waveguide. The launch port of the Ku feed is excited by a probe pair with equal amplitude and antisymmetric. In this way, the main mode (TEM mode) in the coaxial waveguide is suppressed, and the first high-order mode (TE ₁₁ mode) in the coaxial waveguide is excited to the greatest extent; the receiving port of the Ku feed adopts equal amplitude and same phase Symmetrical orthogonal mode pair to stimulate. According to the distribution of modes in the electric field, this method can also be used to suppress the TEM mode in the coaxial waveguide and excite the TE ₁₁ mode to the maximum extent.

The present invention has the following beneficial effects:

(1). Compared with the commonly used dual-band feed source and three-band feed source, the structure of the present invention is more compact and efficient, and simultaneously transmits and receives electromagnetic wave signals of a certain bandwidth, four different polarizations and four frequency bands into the same feed source. .

(2). In the Ku and Ka frequency bands for transceivers, the feed source of the present invention has the characteristics of a rotationally symmetrical radiation pattern, excellent transceiver isolation, good return loss, and low cross polarization.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Among them, 1 is the flange plate, 2 is the tapered dielectric rod, 3 is the inner circular waveguide, 4 is the Ku feed source transmitting SMA connector pair, 6 is the Ku feed source receiving orthogonal mode pair, 7 is the Ka feed source receiving port , 8 is Ka feed launch port

Fig. 2, Fig. 3 are the perspective structure schematic diagrams of the present invention;

Among them, 1 is the flange, 2 is the tapered dielectric rod, 3 is the inner circular waveguide, 4 is the Ku feed source transmitting SMA connector pair, 5 is the symmetrical metal short-circuit column, 6 is the Ku feed source receiving orthogonal mode pair , 7 is Ka feed receiving port, 8 is Ka feed transmitting port, 9 is coaxial waveguide, 10 is circular polarizer, 11 is stepped waveguide

Figure 4 shows the return loss and transceiver isolation of the Ku feed receiving frequency band;

Figure 5 shows the return loss and transceiver isolation of the Ku feed transmitter frequency band;

Figure 6 is the main polarization and cross polarization pattern of the E plane and H plane of the central frequency (12.5 GHz) of the Ku feed receiving frequency band;

Figure 7 is the main polarization and cross polarization pattern of the E plane and H plane of the central frequency (14.25 GHz) of the Ku feed source transmission band;

Figure 8 is the main polarization and cross polarization pattern of the E-plane and H-plane at the center frequency (20.5GHz) of the Ka feed receiving frequency band;

Figure 9 is the main polarization and cross polarization pattern of the E-plane and H-plane at the center frequency (30.3 GHz) of the Ka feed transmitting frequency band;

Fig. 10 is a sectional view of a tapered dielectric rod 2 and an inner circular waveguide 3;

Figure 11 is a system block diagram of a dual-band circularly polarized Ka feed.

Detailed ways

Referring to Fig. 1, the linear circularly polarized four-band Ku/Ka feed source invented in this paper consists of a flange plate 1, a tapered dielectric rod 2, an internal circular waveguide 3, a Ku feed source emitting SMA connector pair 4, and a symmetrical metal short circuit Column 5, Ku feed source receiving orthogonal mode pair 6, Ka feed source receiving port 7, Ka feed source transmitting port 8, coaxial waveguide 9, circular polarizer 10, and ladder waveguide 11. The Ku feed source launch SMA connector pair 4 adopts the 50-ohm SMA connector often used in microwave communication, which can be directly connected to the waveguide coaxial converter, followed by the power divider of the 180° bridge; the symmetrical metal short-circuit column 5 passes through the same The part of the outer waveguide is punched and fixed in the coaxial waveguide 9; the inner circular waveguide 3 in the middle of the feed is fixed by extending the length behind the short-circuit wall of the coaxial waveguide 9.

The present invention works in the Ku and Ka wave bands, and the transmitting SMA connector pair 4 is used for transmitting the frequency band f _T (bandwidth 5%), and the receiving orthogonal mode pair 6 is used for receiving the frequency band f _R (bandwidth 5%) to adjust the transmitting SMA connector pair 4, The position of the receiving orthogonal mode pair 6, the symmetrical metal short-circuit column 5 in the coaxial waveguide 9, the depth of the transmitting SMA connector pair 4 extending into the coaxial waveguide 9, the structural dimensions of the receiving orthogonal mode pair 6 and the stepped waveguide 11 The size of the relative position of the inner circular waveguide. The linear circularly polarized four-band Ku/Ka feed described in this paper has good return loss and transceiver isolation in the Ku and Ka transceiver frequency bands.

The tapered dielectric rod 2 adjusts the main mode TE ₁₁ mode propagating in the inner circular waveguide 3 to the HE ₁₁ mode, and the HE ₁₁ mode can obtain a rotationally symmetric radiation pattern. In order to avoid exciting other excitation modes during design, the cross-section diameter must be properly selected to make them work in the cut-off state. Generally, it is only necessary to avoid generating asymmetric waves HE ₁₂ and EH ₁₂ . The inner radius r of the inner circular waveguide 3 and the relative permittivity ε _r of the tapered dielectric rod 2 and the working wavelength λ need to satisfy the following formula:

$\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; *</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; <</span>\frac{\mathrm{<span\; class="notranslate">\; 1.22</span>}}{\sqrt{{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}\mathrm{<span\; class="notranslate">\; \&lambda;</span>}$

First select the appropriate dielectric constant ε _r and the radius r of the inner circular waveguide 3, the material of the tapered dielectric rod 2 in the inner circular waveguide 3 of the feed of the present invention is selected from the commonly used polytetrafluoroethylene; then according to the above formula The radius r of the inner circular waveguide 3 is reasonably selected; by changing the size of the tapered dielectric rod 2 in the inner circular waveguide (see FIG. 10 ), the circular polarization characteristics of the Ka feed can be significantly improved. Within the 5% bandwidth of the Ka feed source transmitting frequency band and receiving frequency band, the axial circular polarization axis ratios are all less than -2dB. In both the Ka receiving frequency band and the transmitting frequency band, the invention has a rotationally symmetrical radiation pattern and good circular polarization characteristics. See Figure 8 and Figure 9. Both the receiving port and the transmitting port in the Ka feed are formed by orthogonal mode couplers. Reasonable size and structure design can achieve good return loss and isolation. Among them, in the transmitting frequency band of the Ka feed source, the return loss is less than -18dB; in the receiving frequency band of the Ka feed source, the return loss is less than -20dB; the transceiver isolation is less than -70dB, which meets the excellent performance requirements.

By setting the symmetrical metal short-circuit column 5 and the Ku feed receiving orthogonal mode pair in the coaxial waveguide, a high transmit-receive isolation of the Ku feed in the working frequency band is realized. Figure 4 and Figure 5 show the Ku feed source transceiver isolation. It can be seen from the simulation results that the transceiver isolation of the Ku feed source dual-band is above 50dB. The electromagnetic wave signal fed by the Ku feed from the transmitting SMA connector pair 4 or the receiving orthogonal mode pair 6 in the coaxial waveguide will cause a large reflection loss if it radiates directly to free space. In the design, we add a stepped conversion waveguide 11 to the outer waveguide of the coaxial waveguide to reduce the reflection loss from the coaxial waveguide to the radiation port, and facilitate the adjustment and matching of the Ku feed within the working frequency range. By properly optimizing the size, the return loss of the Ku feed is less than -10dB in both the transmitting frequency band and the receiving frequency band. See Figure 4 and Figure 5. At the same time, the Ku feed has excellent performance such as rotationally symmetrical far-field radiation patterns in the transmitting and receiving frequency bands, and cross-polarization below -40dB. See Figure 6 and Figure 7.

Therefore, the linear circular polarization integrated high-efficiency and compact four-band feed source performance provided by this patent fully meets the performance requirements of the Lunberg lens antenna, parabolic antenna and other antenna systems for the feed source.

Above, the description of the present invention is provided for those skilled in the art so that they can easily understand and use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art without requiring inventive effort. Accordingly, the invention is not intended to be limited only by the arrangements described herein, but only in accordance with the scope of the appended claims.

Claims (8)

1. the integrated transmitting-receiving feed antenna of Ku/Ka frequency range line circular polarization that is used for satellite communication comprises that based on the coaxial waveguide nested structure ring flange (1), cone-shaped dielectric rod (2), inner circular waveguide (3), Ku feed emission sub-miniature A connector receive orthogonal mode to (6), Ka feed receiving port (7), Ka feed emission port (8), coaxial waveguide (9), circular polarizer (10), ladder waveguide (11) to short circuit metal post (5), the Ku feed of (4), symmetry.Wherein, Ku feed emission sub-miniature A connector adopts 50 ohm of sub-miniature A connectors that often use in the microwave communication to (4), the Ku feed receives orthogonal mode to (6) external national standard rectangular waveguide BJ140, the external BJ220 of Ka feed receiving port (7), the external BJ320 of Ka feed receiving port (8), the metallic reflection post (5) of symmetry is fixed in the middle of the coaxial waveguide (9) by welding or punching.

2. the integrated transmitting-receiving feed antenna of stating according to claim 1 of a kind of Ku/Ka frequency range line circular polarization is characterized in that described Ku feed emission sub-miniature A connector receives orthogonal mode to (4) and Ku feed and (6) are realized receiving and dispatching two-wire polarizes in coaxial waveguide.

3. the integrated transmitting-receiving feed antenna of stating according to claim 1 of a kind of Ku/Ka frequency range line circular polarization is characterized in that the short circuit metal post (5) of described symmetry and Ku feed receive orthogonal mode (6) have been realized the high-isolation of feed in Ku frequency range transmitting-receiving work.

4. the integrated transmitting-receiving feed antenna of stating according to claim 1 of a kind of Ku/Ka frequency range line circular polarization has been introduced ladder waveguide (11) between it is characterized in that in described ring flange (1) and the coaxial waveguide (9).

5. the integrated transmitting-receiving feed antenna of stating according to claim 1 of a kind of Ku/Ka frequency range line circular polarization is characterized in that the selection of described ring flange (1) structure and size.

6. the integrated transmitting-receiving feed antenna of stating according to claim 1 of a kind of Ku/Ka frequency range line circular polarization is characterized in that the selection of described cone-shaped dielectric rod (2) size and position.

7. the integrated transmitting-receiving feed antenna of stating according to claim 1 of a kind of Ku/Ka frequency range line circular polarization is characterized in that the selection of described circular polarizer (10) structure, size and dielectric constant.

8. the integrated transmitting-receiving feed antenna of stating according to claim 1 of a kind of Ku/Ka frequency range line circular polarization is characterized in that the selection of described Ka feed receiving port (7) and Ka feed emission port (8) orthogonal mode structure and size.

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