A broadband circularly polarized diplex feed network
By designing a wideband circularly polarized duplex feed network, employing a three-layer metal layer and waveguide cavity structure, and combining a power divider and an orthogonal coupler, the problems of narrow mid-frequency band and non-compact structure in existing technologies are solved. This achieves a low axial ratio and high isolation transmit/receive sharing function, and is suitable for feed networks of various circularly polarized antennas.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- AEROSPACE STELLAR SPACE TECH APPL CO LTD
- Filing Date
- 2022-12-13
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies struggle to achieve wide-bandwidth, low-axis-ratio, and compact dual-circularly polarized feed networks for both transmit and receive, limiting their application, especially in dual-frequency shared waveguide array antennas and multi-frequency shared small-aperture antennas.
A wideband circularly polarized duplex feed network is designed, which uses a three-layer metal layer connected by screws, containing first and second waveguide cavities, each with a circularly polarized port of different frequencies. Electromagnetic waves are decomposed and synthesized through a power divider and a quadrature coupler, and frequency selection and rotation control are achieved by combining a specific filter.
It achieves low axial ratio and high isolation over a wide bandwidth, meets the requirements for shared transmission and reception, and is suitable for various circularly polarized antennas, especially the feed network for circularly polarized waveguide planar arrays and parabolic antennas. It also features high reliability and ease of fabrication.
Smart Images
Figure CN115939750B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to power supply network technology in the field of satellite communication technology, specifically to a wideband circularly polarized duplex power supply network. Background Technology
[0002] With continuous technological advancements, satellite communications are evolving towards higher frequencies, wider bandwidths, and polarization multiplexing. This presents greater challenges for ground equipment.
[0003] Currently, the main methods for achieving shared dual circular polarization feed networks for both transmit and receive are: using a shared circular polarizer + OMT (Out-of-Mechanical Transport). The disadvantages of this method are that it cannot simultaneously achieve dual circular polarization and has a narrow bandwidth, failing to meet wideband application requirements; another method uses a demultiplexer where the sidewall operates at a low frequency and the through port operates at a high frequency; this method, in a four-port structure on the sidewall, uses a demultiplexer where the sidewall operates at a high frequency and the through port operates at a low frequency; because the waveguide operating at a high frequency on the sidewall is cut off at low frequencies, and a low-pass filter is needed for the through port; and the longitudinal dimension is relatively long. Summary of the Invention
[0004] The purpose of this invention is to provide a wideband circularly polarized duplex feed network, which features wide bandwidth, low axial ratio, and compact structure. Combined with a broadband OMT, it can be well applied to feed networks for transmit and receive shared dual circularly polarized antennas, especially when the feed network structure size is limited, such as dual-frequency shared waveguide array antennas and multi-frequency shared small aperture antennas, and has great application prospects.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A broadband circularly polarized duplex feed network includes three metal layers connected by screws, and a first waveguide cavity and a second waveguide cavity formed within them. The outer surface of the first waveguide cavity has a horizontal polarization port and a vertical polarization port. One side of the first waveguide cavity has a low-frequency left-hand circular polarization port and a low-frequency right-hand circular polarization port. One side of the second waveguide cavity has a high-frequency left-hand circular polarization port and a high-frequency right-hand circular polarization port. A power divider within the first waveguide cavity decomposes electromagnetic waves entering through the horizontal polarization port into received horizontally polarized waves for the receiving channel and transmitted horizontally polarized waves for the transmitting channel, and decomposes electromagnetic waves entering through the vertical polarization port into received vertically polarized waves for the receiving channel. The transmitted vertically polarized wave and received horizontally polarized wave are combined into a single-line polarized signal within the first waveguide cavity via a receiving 90° orthogonal coupler. Depending on the direction of rotation of the incoming wave, the signal is selectively output at either a low-frequency left-hand circular polarization port or a low-frequency right-hand circular polarization port. The transmitted horizontally polarized wave and transmitted vertically polarized wave are converted to the second waveguide cavity via a waveguide bend connecting the first and second waveguide cavities. Within the second waveguide cavity, the signal is combined into a single-line polarized signal via a transmitting 90° orthogonal coupler. Depending on the direction of rotation of the incoming wave, the signal is selectively output at either a high-frequency left-hand circular polarization port or a high-frequency right-hand circular polarization port.
[0007] In some embodiments, the power divider is a T-type three-port power divider, and there are two of them. The two branch terminals of the three-port power divider are respectively connected to the receiving channel and the transmitting channel; the two main terminals of the two three-port power dividers are respectively connected to the horizontal polarization port and the vertical polarization port.
[0008] In some embodiments, the T-type connector has a transmitting impedance filter and a receiving impedance filter on both sides of the branch port, and a cone-shaped block at the center of the T-type connector.
[0009] In some embodiments, the 90° orthogonal coupler is an E-plane 90° orthogonal coupler or an H-plane 90° orthogonal coupler.
[0010] In some embodiments, the impedance filter is a stepped impedance filter.
[0011] In some embodiments, the receiving / resisting filter is L-shaped, works in conjunction with the tuned waveguide, and serves to connect the upper and lower first waveguide cavities and the second waveguide cavities.
[0012] In some embodiments, the high-frequency left-hand circular polarization port and the high-frequency right-hand circular polarization port are standard waveguide ports that can be directly connected to the transmitter.
[0013] In some embodiments, the low-frequency left-hand circular polarization port and the receiving low-frequency right-hand circular polarization port are standard waveguide ports that can be directly connected to the receiver.
[0014] In some embodiments, the broadband circularly polarized duplex feed network is in the shape of a rectangular block, and the rectangular block is made of copper or aluminum.
[0015] The beneficial effects of this invention are as follows:
[0016] The wideband circularly polarized duplex feed network in this invention has a wide operating bandwidth, a standing wave ratio of less than 1.2 within the bandwidth, a circular polarization axial ratio of less than 1dB, high isolation between transmission and reception, and low insertion loss.
[0017] This invention enables simultaneous and time-division multiplexing (TDD) transmission and reception, as well as simultaneous and time-division left and right circular polarization. When used for single circular polarization, the corresponding cross-polarization port can be connected to the load, thus functioning as a feed source for a single-rotation antenna. When used for dual circular polarization, all ports can be connected to the corresponding RF channels. This network can meet the usage requirements of almost all circularly polarized antennas.
[0018] This invention relates to a broadband miniaturized feed network designed for satellite ground communication systems, which is used for shared transmission and reception and polarization multiplexing. It can be used as a feed network for circularly polarized waveguide planar array antennas or as a circularly polarized feed network for parabolic antennas.
[0019] This invention enables different frequency combinations by designing a frequency duplexer corresponding to a specific frequency and a 90° orthogonal coupling network.
[0020] This invention can be directly used in the feed network of a circularly polarized planar array antenna, or it can be used in conjunction with a broadband OMT in the circularly polarized feed network of a parabolic antenna.
[0021] The invented wideband circularly polarized duplex feed network was applied to a parabolic antenna. The experimental results show that in the Ka band, the transmit axial ratio and receive axial ratio are both less than 1dB, the VSWR is better than 1.2, and the transmit-receive isolation is better than 90dB.
[0022] This invention has a compact structure, is easy to process, can ensure processing accuracy through machining, is not very sensitive to assembly accuracy requirements, requires no debugging, and has high reliability. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the overall structure of a broadband circularly polarized duplex power supply network of the present invention from one angle;
[0024] Figure 2 This is a schematic diagram of the overall structure of a broadband circularly polarized duplex power supply network of the present invention from another angle;
[0025] Figure 3 This is an exploded view of a broadband circularly polarized duplex power supply network according to the present invention;
[0026] Figure 4 This is a schematic diagram of the structure of the second metal layer of the present invention at one angle;
[0027] Figure 5 This is a schematic diagram of the second metal layer of the present invention from another angle;
[0028] Figure 6 This is a schematic diagram of the structure of the third metal layer of the present invention;
[0029] Figure 7 This is a schematic diagram of the structure of the first metal layer of the present invention;
[0030] Figure 8 This is a low-frequency return loss characteristic diagram of a broadband circularly polarized duplex feeder network according to the present invention.
[0031] Figure 9 This is a high-frequency return loss characteristic diagram of a broadband circularly polarized duplex feeder network according to the present invention.
[0032] Figure 10 This is a phase difference characteristic diagram of two orthogonal electric fields in the low-frequency band of a broadband circularly polarized duplex power supply network according to the present invention.
[0033] Figure 11 This is a phase difference characteristic diagram of two orthogonal electric fields in the high-frequency band of a broadband circularly polarized duplex feeder network according to the present invention.
[0034] Explanation of reference numerals in the attached drawings: First metal layer 1, Second metal layer 2, Third metal layer 3, Screw 4, First waveguide cavity 5, Second waveguide cavity 6, Duplexer T-head 51, Transmitter stop filter 52, Receiver stop filter 53, Receiver 90° orthogonal coupler 54, Conical block 55, Waveguide bend 61, Transmitter 90° orthogonal coupler 62, Horizontal polarization port 71, Vertical polarization port 72, Low-frequency left-hand circular polarization port 73, Low-frequency right-hand circular polarization port 74, High-frequency left-hand circular polarization port 75, High-frequency right-hand circular polarization port 76. Detailed Implementation
[0035] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0036] like Figure 1-11As shown, this invention provides a broadband circularly polarized duplex feed network, which is rectangular in shape. The rectangular block includes a first metal layer 1, a second metal layer 2, and a third metal layer 3 connected by screws 4, and a first waveguide cavity 5 and a second waveguide cavity 6 formed inside it. The screws 4 are arranged along both sides of the waveguide, with a density less than λmin / 4. The upper surface of the first metal layer 1 is provided with a horizontal polarization port 71 and a vertical polarization port 72. The low-frequency left-hand circular polarization port 73 and the low-frequency right-hand circular polarization port 74 are located on the same horizontal plane on one side of the first waveguide cavity 5. The high-frequency left-hand circular polarization port 75 and the high-frequency right-hand circular polarization port 76 are located on the same horizontal plane on one side of the second waveguide cavity 6. The T-shaped head 51 in the first waveguide cavity 5, as well as the transmit blocking filter 52 and the receive blocking filter 53 arranged on both sides thereon, decompose the electromagnetic wave entering the horizontal polarization port 71 into the receive horizontally polarized wave and the transmit horizontally polarized wave of the receiving channel. The horizontally polarized wave emitted by the transmission channel decomposes the electromagnetic wave entering the vertical polarization port 72 into a vertically polarized wave received by the receiving channel and a vertically polarized wave emitted by the transmission channel. The horizontally polarized wave and the vertically polarized wave received enter the two ports on the same side of the four-port receiving 90° orthogonal coupler 54. The receiving 90° orthogonal coupler combines two equal-amplitude signals with a 90° phase difference into a single-line polarized signal. Depending on the direction of rotation of the incoming wave, it is selectively output at the low-frequency left-hand circular polarization port 73 or the low-frequency right-hand circular polarization port 74. The horizontally polarized wave emitted and the vertically polarized wave emitted are converted to the second waveguide cavity 6 via the waveguide bend and the stepped matching section. The transmitting 90° orthogonal coupler 62 inside combines two equal-amplitude signals with a 90° phase difference into a single-line polarized signal. Depending on the direction of rotation of the incoming wave, it is selectively output at the high-frequency left-hand circular polarization port 75 or the high-frequency right-hand circular polarization port 76.
[0037] In some embodiments, the first waveguide cavity 5 is provided with two T-type heads 51, two transmit blocking filters 52, two receive blocking filters 53, and two receive 90° orthogonal couplers 54; the T-type head 51 is a three-port power divider that splits one into two, and a conical block 55 is provided at the center of the T-type head. The port facing the T-type head 51 is connected to the horizontal polarization port 71 and the vertical polarization port 72. The conical block is used to achieve impedance matching. The side wall opening on the same layer as the conical block 55 is the receiving branch. The receiving branch is directly connected to two transmitting stop filters 52, two receiving 90° orthogonal couplers 54, and low-frequency left-hand circular polarization port 73 and low-frequency right-hand circular polarization port 74 in sequence. The side wall opening on the other side of the conical block 55 is the transmitting branch. The transmitting branch is connected to the receiving stop filter 53 through the matching step, and is converted to the second waveguide cavity 6 through the waveguide bend 61 and the step matching section. It is then connected to the two transmitting 90° orthogonal couplers 54, the high-frequency left-hand circular polarization port 75, and the high-frequency right-hand circular polarization port 76 in sequence in the second waveguide cavity 6.
[0038] Furthermore, the impedance filter 52 is a stepped impedance type filter.
[0039] Furthermore, the receiving and resisting filter 53 is L-shaped and, in conjunction with the tuning waveguide, serves to connect the upper and lower first waveguide cavities and the second waveguide cavities.
[0040] Furthermore, the high-frequency left-hand circular polarization port 75 and the high-frequency right-hand circular polarization port 76 are standard waveguide ports that can be directly connected to the transmitter, specifically, they can be standard flanges.
[0041] Furthermore, the low-frequency left-hand circular polarization port 73 and the receiving low-frequency right-hand circular polarization port 74 are standard waveguide ports that can be directly connected to the receiver, specifically, they can be standard flanges.
[0042] Furthermore, the receiving 90° orthogonal coupler 54 or the transmitting 90° orthogonal coupler is an E-plane orthogonal coupler or an H-plane orthogonal coupler.
[0043] Furthermore, the rectangular block is made of copper or aluminum.
[0044] like Figure 1 The broadband circularly polarized duplex feed network shown has the following main structural parameters: horizontal and vertical polarization port BJ260; transmit left-hand circular polarization port, high-frequency right-hand circular polarization port BJ320; receive left-hand circular polarization port, low-frequency right-hand circular polarization port BJ220; overall size: 85mm*50mm*40mm.
[0045] The following combination Figures 1-11 The working principle of this invention will be explained as follows:
[0046] When used for reception: The circularly polarized wave received by the antenna is transformed into a horizontally polarized wave and a vertically polarized wave by an equal-phase orthogonal mode coupler. The horizontally polarized wave and the vertically polarized wave have the same amplitude and are 90° out of phase. They enter the horizontally polarized port and the vertically polarized port of the six-port polarized duplex feed network. After passing through the duplexer T-head and the cut-through and cut-through filters on both sides, the electromagnetic wave entering the horizontally polarized port is decomposed into the received horizontally polarized wave of the receiving channel and the transmitted horizontally polarized wave of the transmitting channel. The electromagnetic wave entering the vertically polarized port is decomposed into the received vertically polarized wave of the receiving channel and the transmitted vertically polarized wave of the transmitting channel. Since the two channels are exactly the same, the received horizontally polarized wave and the received vertically polarized wave are still equal in amplitude and 90° out of phase, and the transmitted horizontally polarized wave and the transmitted vertically polarized wave are also still equal in amplitude and 90° out of phase. Next, the horizontally polarized wave and the vertically polarized wave are received at the two ports on the same side of the four-port receiving 90° quadrature coupler. The 90° quadrature coupler combines the two equal-amplitude signals with a 90° phase difference into a single-line polarized signal. Depending on the direction of rotation of the incoming wave, the signal is selectively output at the left-hand or right-hand polarized port.
[0047] When used for transmission, the principle is the same as when used for reception, but the signal flow is reversed. The horizontally polarized wave and the vertically polarized wave are transmitted and converted to the second waveguide cavity 6 via the waveguide bend and stepped matching section. The transmitting 90° orthogonal coupler 62 inside the cavity combines the two equal-amplitude signals with a 90° phase difference into a single-line polarized signal. Depending on the direction of the incoming wave, the signal is selectively output at the high-frequency left-hand circular polarization port 75 or the high-frequency right-hand circular polarization port 76.
[0048] Figures 8-11 These are the main electrical performance indicators that can be achieved in this embodiment. Figure 8 and Figure 9 The figures show the return loss curves of this invention in the low-frequency and high-frequency bands, respectively. As can be seen from the figures, in the frequency range of 17GHz to 20GHz, the return loss is better than 20dB, corresponding to a voltage standing wave ratio (VSWR) better than 1.2. In the frequency range of 24.5GHz to 28GHz, the return loss is better than 25dB, corresponding to a VSWR better than 1.1. Good VSWR characteristics are achieved in both the high-frequency and low-frequency bands.
[0049] Figure 10 and Figure 11 These are the phase difference characteristic curves of the two orthogonal modes in the low-frequency and high-frequency bands of this invention. The phase difference characteristic corresponds to the axial ratio. Ideally, the phase difference is ±90°. As can be seen from the figure, in the frequency range of 17.5GHz~19.5GHz, the phase difference of the two orthogonal polarizations is better than 90°±1°, corresponding to a voltage standing wave ratio (VSWR) better than 1.2. In the frequency range of 24.5GHz~27.5GHz, the return loss is better than 90°±2°. Under the premise of ensuring processing accuracy, the network of this invention can achieve an axial ratio better than 0.3dB, achieving excellent axial ratio characteristics in both the high-frequency and low-frequency bands.
[0050] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A broadband circularly polarized duplex feeder network, characterized in that, The device includes a rectangular block consisting of a first metal layer (1), a second metal layer (2), and a third metal layer (3) connected by screws (4), and a first waveguide cavity (5) and a second waveguide cavity (6) formed inside the rectangular block. The outer surface of the first waveguide cavity (5) is provided with a horizontal polarization port (71) and a vertical polarization port (72). A low-frequency left-hand circular polarization port (73) and a low-frequency right-hand circular polarization port (74) are provided on one side of the first waveguide cavity (5). A high-frequency left-hand circular polarization port (75) and a high-frequency right-hand circular polarization port (76) are provided on one side of the second waveguide cavity (6). The first waveguide cavity (5) is provided with a T-shaped head (51), which is a three-port power divider. The center of the T-shaped head (51) is provided with a cone-shaped block (55). The two branch ports of the T-shaped head are respectively connected to the receiving channel and the transmitting channel. The main port of the T-shaped head is respectively connected to the horizontal polarization port (71) and the vertical polarization port (72). The two sides of the T-shaped head are also provided with a transmitting impedance filter (52) and a receiving impedance filter (53) to decompose the electromagnetic waves from the horizontal polarization port (71) and the vertical polarization port (72). The electromagnetic waves from the horizontal polarization port (71) are decomposed into the receiving horizontal polarization wave of the receiving channel and the transmitting horizontal polarization wave of the transmitting channel. The electromagnetic waves from the vertical polarization port (72) are decomposed into the receiving vertical polarization wave of the receiving channel and the transmitting vertical polarization wave of the transmitting channel. The received horizontally polarized wave and the received vertically polarized wave are combined into a single-line polarized signal in the first waveguide cavity (5) through a receiving 90° orthogonal coupler (54). Depending on the direction of the incoming wave, the signal is selectively output at a low-frequency left-hand circular polarization port (73) or a low-frequency right-hand circular polarization port (74). The transmitted horizontally polarized wave and the transmitted vertically polarized wave are converted to the second waveguide cavity (6) via a waveguide bend (61) connecting the first waveguide cavity (5) and the second waveguide cavity (6). The transmitted signal is combined into a single-line polarized signal in the second waveguide cavity (6) through a transmitting 90° orthogonal coupler (62). Depending on the direction of the incoming wave, the signal is selectively output at a high-frequency left-hand circular polarization port (75) or a high-frequency right-hand circular polarization port (76).
2. The broadband circularly polarized duplex power supply network according to claim 1, characterized in that, The number of three-port power dividers is two. The two branch terminals of the three-port power dividers are connected to the receiving channel and the transmitting channel, respectively. The two main terminals of the two three-port power dividers are connected to the horizontal polarization port (71) and the vertical polarization port (72), respectively.
3. The broadband circularly polarized duplex power supply network according to claim 1, characterized in that, The 90° orthogonal coupler is either an E-plane 90° orthogonal coupler or an H-plane 90° orthogonal coupler.
4. The broadband circularly polarized duplex power supply network according to claim 1, characterized in that, The impedance filter (52) is a stepped impedance filter.
5. The broadband circularly polarized duplex power supply network according to claim 1, characterized in that, The receiving filter (53) is L-shaped, works in conjunction with the tuning waveguide, and serves to connect the upper and lower first waveguide cavities and the second waveguide cavities.
6. The broadband circularly polarized duplex power supply network according to claim 1, characterized in that, The high-frequency left-hand circular polarization port (75) and the high-frequency right-hand circular polarization port (76) are standard waveguide ports that can be directly connected to the transmitter.
7. The broadband circularly polarized duplex power supply network according to claim 1, characterized in that, The low-frequency left-hand circular polarization port (73) and the low-frequency right-hand circular polarization port (74) are standard waveguide ports and can be directly connected to the receiver.
8. The broadband circularly polarized duplex power supply network according to claim 1, characterized in that, The rectangular block is made of copper or aluminum.