Antenna structure and low-orbit satellite system

Abstract

The antenna structure comprises an upper patch antenna, a lower patch antenna, a grounding layer, a transmission line layer, a first feed-in line and a second feed-in line. The lower patch antenna is located between the upper patch antenna and the grounding layer. The grounding layer is located between the lower patch antenna and the transmission line layer. The first feed-in line and the second feed-in line pass through the grounding layer and are coupled between the transmission line layer and the lower patch antenna. The first feed-in line and the second feed-in line respectively comprise a first part, a second part and a third part. The first part is located between the lower patch antenna and the grounding layer and is perpendicular to the extension direction of the grounding layer. The second part is located between the grounding layer and the transmission line layer and is perpendicular to the extension direction of the grounding layer. The third part is located on the grounding layer and parallel to the extension direction of the grounding layer. The third portion is coupled between the first portion and the second portion. The substrates of the elements of the antenna structure all comprise liquid crystal polymer materials, have the characteristics of moisture absorption resistance, good environmental tolerance and low loss, and can improve the transmission loss.

Description

Technical Field

[0001] The present invention relates to an antenna structure, and in particular to an antenna structure and a low-orbit satellite system. Background Art

[0002] To implement low-orbit satellite communications, beamforming technology is required. For example, using a beamforming IC requires 4 antennas. A small base station for low-orbit satellites requires at least 256 beamforming ICs, a total of 1024 antennas, and different groups of antennas are used for uploading and downloading, a total of 2048 antennas. As can be seen from this, its size is large, so its mainstream market is for vehicle-mounted use, placed on the roof, so that it can be used in places with poor signals in the wilderness. Because it is a vehicle-mounted product, it will be affected by the environment, such as rain. Therefore, how to improve its environmental tolerance is a topic that needs to be worked on in today's low-orbit satellite communications. In addition, 256 beamforming ICs require multi-stage power dividers, so how to reduce its line loss is also a topic that needs to be worked on in today's low-orbit satellite communications. Summary of the invention

[0003] The object of the present invention is to propose an antenna structure, comprising an upper patch antenna, a lower patch antenna, a ground layer, a transmission line layer, a first feed line and a second feed line. The lower patch antenna comprises a first feed point and a second feed point. The upper patch antenna and the lower patch antenna have a circular shape, and the area of ​​the upper patch antenna is smaller than the area of ​​the lower patch antenna. The lower patch antenna is located between the upper patch antenna and the ground layer. The ground layer is located between the lower patch antenna and the transmission line layer. The first feed line passes through the ground layer and is coupled between the transmission line layer and the first feed point of the lower patch antenna. The second feed line passes through the ground layer and is coupled between the transmission line layer and the second feed point of the lower patch antenna. The first feed line and the second feed line are orthogonal to each other, and each of the first feed line and the second feed line comprises a first part, a second part and a third part. The first part is located between the lower patch antenna and the ground layer and is perpendicular to the extension direction of the ground layer. The second part is located between the ground layer and the transmission line layer and is perpendicular to the extension direction of the ground layer. The third portion is located on the ground layer and is parallel to the extending direction of the ground layer. The third portion is coupled between the first portion and the second portion.

[0004] In some embodiments, the antenna structure further includes a first substrate, an air layer, a second substrate, and a third substrate. The first substrate is located between the upper patch antenna and the lower patch antenna. The air layer is located between the first substrate and the lower patch antenna. The second substrate is located between the lower patch antenna and the ground layer. The third substrate is located between the ground layer and the transmission line layer. Each of the first substrate, the second substrate, and the third substrate includes a liquid crystal polymer material.

[0005] In some embodiments, the ground layer has an upper surface close to the lower patch antenna and a lower surface away from the lower patch antenna, the ground layer includes a first upper opening and a second upper opening located on the upper surface and a first lower opening and a second lower opening located on the lower surface, the first portion of the first feed line is coupled to the third portion of the first feed line through the first upper opening, the first portion of the second feed line is coupled to the third portion of the second feed line through the second upper opening, the second portion of the first feed line is coupled to the third portion of the first feed line through the first lower opening, the second portion of the second feed line is coupled to the third portion of the second feed line through the second lower opening, the vertical projections of the first upper opening and the first lower opening on the ground layer do not overlap with each other, and the vertical projections of the second upper opening and the second lower opening on the ground layer do not overlap with each other.

[0006] In some embodiments, the first feeding line and the second feeding line receive a first feeding signal and a second feeding signal respectively, and an extension direction of the third portion of the first feeding line is orthogonal to an extension direction of the third portion of the second feeding line.

[0007] In some embodiments, the grounding layer also includes a first slot and a second slot penetrating the grounding layer, the first slot is adjacent to the first upper opening and the first upper opening is located between the first slot and the first lower opening, and the second slot is adjacent to the second upper opening and the second upper opening is located between the second slot and the second lower opening.

[0008] In some embodiments, the first slot and the second slot have a rectangular shape or an elliptical shape, wherein when the first slot and the second slot have a rectangular shape, the extension direction of the long side of the first slot is orthogonal to the extension direction of the third portion of the first feed line and the extension direction of the long side of the second slot is orthogonal to the extension direction of the third portion of the second feed line, wherein when the first slot and the second slot have an elliptical shape, the extension direction of the long axis of the first slot is orthogonal to the extension direction of the third portion of the first feed line and the extension direction of the long axis of the second slot is orthogonal to the extension direction of the third portion of the second feed line.

[0009] The object of the present invention is to propose another low-orbit satellite system, including an antenna structure, a beamforming chip, a bandpass filter, an up-down converter and a digital signal processor. The antenna structure is used to receive a first radio frequency signal or send a second radio frequency signal. The beamforming chip is coupled to the antenna structure to beamform the first radio frequency signal. The bandpass filter is coupled to the beamforming chip to bandpass filter the first radio frequency signal. The up-down converter is coupled to the bandpass filter to downconvert the first radio frequency signal to a first baseband signal, and the up-down converter is also used to upconvert the second baseband signal to a second radio frequency signal. The digital signal processor is coupled to the up-down converter to perform digital signal processing on the first baseband signal, and the digital signal processor is also used to generate a second baseband signal. The antenna structure includes an upper patch antenna, a lower patch antenna, a ground layer, a transmission line layer, a first feed line and a second feed line. The lower patch antenna includes a first feed point and a second feed point. The upper patch antenna and the lower patch antenna have a circular shape, and the area of ​​the upper patch antenna is smaller than the area of ​​the lower patch antenna. The lower patch antenna is located between the upper patch antenna and the ground layer. The ground layer is located between the lower patch antenna and the transmission line layer. The first feed line passes through the ground layer and is coupled between the transmission line layer and the first feeding point of the lower patch antenna. The second feed line passes through the ground layer and is coupled between the transmission line layer and the second feeding point of the lower patch antenna. The first feed line and the second feed line are orthogonal to each other, and each of the first feed line and the second feed line includes a first part, a second part and a third part. The first part is located between the lower patch antenna and the ground layer and is perpendicular to the extension direction of the ground layer. The second part is located between the ground layer and the transmission line layer and is perpendicular to the extension direction of the ground layer. The third part is located in the ground layer and is parallel to the extension direction of the ground layer. The third part is coupled between the first part and the second part.

[0010] In some embodiments, the bandpass filter includes a substrate, two stepped impedance resonators symmetrically arranged on the upper surface of the substrate, and a metal ground plate arranged on the lower surface of the substrate, each stepped impedance resonator is an open-circuit ring resonator, the substrate of the bandpass filter includes a liquid crystal polymer material, and the substrate of each of the beamforming chip, the up-down converter and the digital signal processor includes a liquid crystal polymer material.

[0011] In some embodiments, each stepped impedance resonator is a three-step stepped impedance resonator, including two first impedance segments, two second impedance segments, a third impedance segment, and an input and output end connected to the third impedance segment, the third impedance segment is connected between the two second impedance segments, one of the two first impedance segments is connected to one of the two second impedance segments, the other of the two first impedance segments is connected to the other of the two second impedance segments, and the two first impedance segments are adjacent to each other but do not contact each other.

[0012] In some embodiments, the impedance of each first impedance segment is smaller than the impedance of each second impedance segment, the impedance of the third impedance segment is smaller than the impedance of each second impedance segment, the line width of each first impedance segment is larger than the line width of each second impedance segment, and the line width of the third impedance segment is larger than the line width of each second impedance segment.

[0013] In some embodiments, the two first impedance segments, the two second impedance segments and the third impedance segment of each stepped impedance resonator form a C-shaped coupling structure, the characteristic impedance of the input and output ends is 50 ohms, and the input and output ends use transmission lines in the form of fan-shaped gradient lines to feed signals.

[0014] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below with reference to the accompanying drawings for detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be better understood from the following detailed description in conjunction with the accompanying drawings. It should be noted that, in accordance with standard industry practice, the features are not drawn to scale. In fact, the dimensions of the features may be increased or decreased at will to make the discussion clearer.

[0016] Figure 1 is a system block diagram of a low-orbit satellite system according to an embodiment of the present invention;

[0017] Figure 2 is a schematic cross-sectional view of an antenna structure according to an embodiment of the present invention;

[0018] Figure 3 is a schematic cross-sectional view of an antenna structure according to an embodiment of the present invention;

[0019] Figure 4 is a top perspective view of an antenna structure according to an embodiment of the present invention;

[0020] Figure 5 is a top perspective view of an antenna structure according to another embodiment of the present invention;

[0021] Figure 6 is an S-parameter diagram of an antenna structure according to an embodiment of the present invention;

[0022] Figure 7 is a schematic structural diagram of a bandpass filter according to an embodiment of the present invention;

[0023] Figure 8 is an S-parameter diagram of a bandpass filter according to an embodiment of the present invention;

[0024] Fig. 9 is an S-parameter diagram of a low-orbit satellite system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following is a detailed discussion of embodiments of the present invention. However, it is understood that the embodiments provide many applicable concepts that can be implemented in a variety of specific contexts. The embodiments discussed and disclosed are for illustration only and are not intended to limit the scope of the present invention. As used herein, "first", "second", ..., etc., do not specifically refer to the meaning of order or sequence, but are only used to distinguish between elements or operations described in the same technical terms.

[0026] Figure 1 1 is a system block diagram of a low-Earth Orbit (LEO) Satellite system 1 according to an embodiment of the present invention. The low-Earth Orbit satellite system 1 includes an antenna structure 10, a beamforming chip 20, a bandpass filter 30, an up-down converter 40 and a digital signal processor 50.

[0027] Specifically, the low-orbit satellite system 1 is a beam scanning system using a low-orbit satellite for implementing low-orbit satellite communications. The low-orbit satellite system 1 can transmit and receive satellite signals in a directional manner through the "beamforming" characteristics of the beamforming chip 20, thereby reducing signal interference through directional transmission, and because the antenna structure 10 operates in a higher frequency band (such as the Ka band), it helps to improve the poor signal situation in remote areas.

[0028] In the receiving mode of the low-orbit satellite system 1, the beamforming chip 20 is coupled to the antenna structure 10 to beamform the first RF signal (i.e., to beamform the radiation pattern of the antenna), so that the antenna structure 10 is used to receive the first RF signal. The bandpass filter 30 is coupled to the beamforming chip 20 to perform bandpass filtering on the first RF signal. The up-down converter 40 is coupled to the bandpass filter 30 to down-convert the first RF signal to a first baseband signal. The digital signal processor 50 is coupled to the up-down converter 40 to perform digital signal processing on the first baseband signal.

[0029] In the transmission mode of the low-orbit satellite system 1, the digital signal processor 50 is also used to generate a second baseband signal, and the up-down converter 40 is also used to up-convert the second baseband signal into a second radio frequency signal. The radiation pattern of the antenna is beamformed by the beamforming chip 20, and then the second radio frequency signal is sent in a specific direction through the antenna structure 10.

[0030] In other embodiments of the present invention, in addition to the bandpass filter 30, the low-orbit satellite system 1 may further include a mixer and / or a low noise amplifier for performing signal processing on the first RF signal in the reception mode of the low-orbit satellite system 1. In still other embodiments of the present invention, in addition to the bandpass filter 30, the low-orbit satellite system 1 may further include a mixer and / or a power amplifier for performing signal processing on the second RF signal in the transmission mode of the low-orbit satellite system 1.

[0031] The digital signal processor 50 can generate a second baseband signal to be transmitted by processing a signal containing information to be transmitted, and can generate a signal containing information by processing a received first baseband signal. For example, the digital signal processor 50 may include an encoder, a modulator, and a digital-to-analog converter to generate a second baseband signal to be transmitted. In addition, the digital signal processor 50 may include an analog-to-digital converter, a demodulator, and a decoder to process the received first baseband signal. The digital signal processor 50 can set a transmission mode or a reception mode. In some embodiments, the digital signal processor 50 may include one or more cores and a memory storing instructions executed by the one or more cores, and at least a portion of the digital signal processor 50 may include a software block stored in the memory. In some embodiments, the digital signal processor 50 may include a logic circuit designed by logic synthesis, and at least a portion of the digital signal processor 50 may include a hardware block implemented as a logic circuit.

[0032] Figure 2 and Figure 3 is a cross-sectional schematic diagram of an antenna structure 10 according to an embodiment of the present invention, wherein Figure 2 is a cross-sectional view along the XZ plane, and Figure 3 It is a cross-sectional view along the YZ plane. Figure 4 is a top perspective view of an antenna structure 10 according to an embodiment of the present invention, wherein Figure 4 is the top view direction of the antenna structure 10 (eg Figure 4 perspective view of the Z direction).

[0033] Please refer to Figure 2 , Figure 3 and Figure 4 The antenna structure 10 includes an upper patch antenna 100, a lower patch antenna 200, a ground layer 300, a transmission line layer 400, a first feed line T1 and a second feed line T2. Figure 2 and Figure 3As shown, the lower patch antenna 200 is located between the upper patch antenna 100 and the ground layer 300, and the ground layer 300 is located between the lower patch antenna 200 and the transmission line layer 400. The upper patch antenna 100, the lower patch antenna 200 and the ground layer 300 can be made of a metal plate or a metal piece.

[0034] like Figure 2 and Figure 3 As shown, the lower patch antenna 200 includes a first feeding point P1 and a second feeding point P2. Figure 2 As shown, the first feeding line T1 passes through the ground layer 300 and is coupled between the transmission line layer 400 and the first feeding point P1 of the lower patch antenna 200. Figure 3 As shown, the second feeding line T2 passes through the ground layer 300 and is coupled between the transmission line layer 400 and the second feeding point P2 of the lower patch antenna 200 .

[0035] like Figure 2 As shown, the first feeding line T1 includes a first portion T11, a second portion T12 and a third portion T13. The third portion T13 is coupled between the first portion T11 and the second portion T12. The first portion T11 is located between the lower patch antenna 200 and the ground layer 300 and is perpendicular to the extension direction of the ground layer 300 (eg, Figure 2 The second portion T12 is located between the ground layer 300 and the transmission line layer 400 and is perpendicular to the extension direction of the ground layer 300 (eg Figure 2 The third portion T13 is located in the ground layer 300 and is parallel to the extension direction of the ground layer 300 (eg Figure 2 in the X direction).

[0036] like Figure 3 As shown, the second feeding line T2 includes a first portion T21, a second portion T22 and a third portion T23. The third portion T23 is coupled between the first portion T21 and the second portion T22. The first portion T21 is located between the lower patch antenna 200 and the ground layer 300 and is perpendicular to the extension direction of the ground layer 300 (eg, Figure 3 The second portion T22 is located between the ground layer 300 and the transmission line layer 400 and is perpendicular to the extension direction of the ground layer 300 (eg Figure 3 The third portion T23 is located in the ground layer 300 and is parallel to the extending direction of the ground layer 300 (eg, Figure 3 Y direction).

[0037] like Figure 4As shown, the upper patch antenna 100 and the lower patch antenna 200 have a circular shape, and the area of ​​the upper patch antenna 100 is smaller than the area of ​​the lower patch antenna 200. Specifically, the upper patch antenna 100 presents a first circle, and the lower patch antenna 200 presents a second circle, wherein the area of ​​the first circle is slightly smaller than the area of ​​the second circle. In addition, if the upper patch antenna 100 has a first vertical projection (Vertical Projection) on the ground layer 300 and the lower patch antenna 200 has a second vertical projection on the ground layer 300, the first vertical projection will be completely located inside the second vertical projection, and the combination of the first vertical projection and the second vertical projection will present concentric circles.

[0038] In detail, the upper patch antenna 100 and the lower patch antenna 200 are stacked parallel to each other to form a double-layer circular patch antenna design. The upper patch antenna 100 is completely separated from the lower patch antenna 200 and is in a floating state. The upper patch antenna 100 can be used to receive part of the electromagnetic waves from the lower patch antenna 200, thereby stimulating the upper patch antenna 100 to radiate electromagnetic waves in a similar frequency band, thereby improving the gain and bandwidth of the antenna structure 10.

[0039] The lower patch antenna 200 includes a first feeding point P1 and a second feeding point P2 to radiate electromagnetic wave signals, and the electromagnetic wave signals are respectively supplied to the first feeding point P1 and the second feeding point P2 through the first feeding line T1 and the second feeding line T2. In other words, the upper patch antenna 100 is used for coupling, and the lower patch antenna 200 is used for direct excitation.

[0040] The antenna structure 10 further includes a first substrate 500, an air layer 600, a second substrate 700 and a third substrate 800. The first substrate 500 is located between the upper patch antenna 100 and the lower patch antenna 200. The air layer 600 is located between the first substrate 500 and the lower patch antenna 200. The second substrate 700 is located between the lower patch antenna 200 and the ground layer 300. The third substrate 800 is located between the ground layer 300 and the transmission line layer 400. The function of the air layer 600 is to reduce the dielectric constant of the first substrate to reduce the Q value of the antenna structure 10, thereby increasing the bandwidth and gain of the antenna structure 10. At the same time, air has the lowest loss among all media. In addition, the thickness of the air layer 600 can be adjusted to increase the flexibility of adjusting the bandwidth, beam, or impedance matching during design.

[0041] Each of the first substrate 500, the second substrate 700 and the third substrate 800 includes a liquid crystal polymer (LCP) material. Since the liquid crystal polymer material has good anti-hygroscopicity, it has good environmental tolerance and is not easily affected by the environment (such as rain, etc.), so it is convenient to use as a vehicle antenna and is suitable for being placed on the roof for use in wilderness areas with poor signals.

[0042] In some embodiments, the first substrate 500 , the second substrate 700 , and the third substrate 800 may be flexible substrates containing liquid crystal polymer materials to provide a bending function.

[0043] The ground layer 300 has an upper surface 300U close to the lower patch antenna 200 and a lower surface 300L away from the lower patch antenna 200. The ground layer 300 includes a first upper opening U1 and a second upper opening U2 located on the upper surface 300U and a first lower opening L1 and a second lower opening L2 located on the lower surface 300L. The first portion T11 of the first feed line T1 is coupled to the third portion T13 of the first feed line T1 through the first upper opening U1, the first portion T21 of the second feed line T2 is coupled to the third portion T23 of the second feed line T2 through the second upper opening U2, the second portion T12 of the first feed line T1 is coupled to the third portion T13 of the first feed line T1 through the first lower opening L1, and the second portion T22 of the second feed line T2 is coupled to the third portion T23 of the second feed line T2 through the second lower opening L2.

[0044] The vertical projections of the first upper opening U1 and the first lower opening L1 on the ground layer 300 do not overlap each other, that is, the first upper opening U1 and the first lower opening L1 are located along the top view direction of the antenna structure 10 (eg Figure 4 Specifically, the vertical projections of the first upper opening U1 and the first lower opening L1 in the top view direction of the antenna structure 10 (eg, Figure 4 A staggered hole design is used instead of a stacked hole design in the Z direction to reduce the requirements for alignment accuracy when components are stacked, which can improve the process yield of the antenna structure 10 and enhance the isolation of the antenna structure 10.

[0045] The vertical projections of the second upper opening U2 and the second lower opening L2 on the ground layer 300 do not overlap each other, that is, the second upper opening U2 and the second lower opening L2 are located along the top view direction of the antenna structure 10 (eg Figure 4 Specifically, the vertical projections of the second upper opening U2 and the second lower opening L2 in the top view direction of the antenna structure 10 (eg, Figure 4 A staggered hole design is used instead of a stacked hole design in the Z direction to reduce the requirements for alignment accuracy when components are stacked, which can improve the process yield of the antenna structure 10 and enhance the isolation of the antenna structure 10.

[0046] The first upper opening U1 , the first lower opening L1 , the second upper opening U2 , and the second lower opening L2 may be circular openings or square openings, but are not limited thereto.

[0047] The transmission line layer 400 is a 50 ohm transmission line. The first feed line T1 and the second feed line T2 receive the first feed signal F1 and the second feed signal F2 from the transmission line layer 400, respectively. The first feed signal F1 is orthogonal to the second feed signal F2. In other words, the antenna structure 10 is orthogonal feeding. The extension direction of the third portion T13 of the first feed line T1 (eg Figure 2 The X direction) is orthogonal to the extension direction of the third portion T23 of the second feeding line T2 (eg Figure 3 Y direction).

[0048] The first feed line T1 may be a first coaxial cable, wherein the central conductive line of the first coaxial cable is coupled to the first feed point P1, and the conductive housing of the first coaxial cable is coupled to the ground layer 300 but does not directly contact the lower patch antenna 200. The second feed line T2 may be a second coaxial cable, wherein the central conductive line of the second coaxial cable is coupled to the second feed point P2, and the conductive housing of the second coaxial cable is coupled to the ground layer 300 but does not directly contact the lower patch antenna 200. The transmission line layer 400 is used to generate a feed signal / electromagnetic wave signal (i.e., a first feed signal F1 and a second feed signal F2) with the same operating frequency and provide them to the first feed line T1 and the second feed line T2 respectively, so as to excite the antenna structure 10 and achieve dual-polarization characteristics.

[0049] In terms of antenna principle, the first feed line T1 provides a first polarization direction and the second feed line T2 provides a second polarization direction. By using the first feed line T1 and the second feed line T2 at the same time, a dual-coupling-fed and dual-polarized patch antenna structure 10 can be formed. It should be noted that since the first feed point P1 and the second feed point P2 each generate an effective feeding capacitor with the lower patch antenna 200, the bandwidth of the antenna structure 10 can be greatly increased. Furthermore, this dual-feed mechanism can also improve the cross-polarization isolation (XPI) of the antenna structure 10. On the other hand, the isolation between the first feed line T1 and the second feed line T2 can be increased by using the ground layer 300 to separate the first feed line T1 and the second feed line T2.

[0050] The grounding layer 300 further includes a first slot S1 and a second slot S2 penetrating the grounding layer 300, wherein the first slot S1 is adjacent to the first upper opening U1 and is located between the first slot S1 and the first lower opening L1, and the second slot S2 is adjacent to the second upper opening U2 and is located between the second slot S2 and the second lower opening L2. Specifically, the grounding layer 300 of the antenna structure 10 further includes the first slot S1 near the first upper opening U1 and the second slot S2 at the second upper opening U2, so that the antenna structure 10 has a broadband effect and the isolation of the antenna structure 10 is as high as -20 dB.

[0051] The first slot S1 and the second slot S2 are located in the top view direction of the antenna structure 10 (eg Figure 4 The first slot S1 has a rectangular shape, and the extension direction of the long side of the first slot S1 (such as Figure 4 The Y direction) is orthogonal to the extension direction of the third portion T13 of the first feeding line T1 (eg Figure 4 The X direction), the extension direction of the long side of the second slot S2 (such as Figure 4 The X direction) is orthogonal to the extension direction of the third portion T23 of the second feeding line T2 (eg Figure 4 Y direction).

[0052] Figure 5 1 is a top perspective view of an antenna structure 10 according to another embodiment of the present invention. The first slot S1 and the second slot S2 are located in the top view direction of the antenna structure 10 (eg Figure 5 The Z direction) has an elliptical shape, and the extension direction of the long axis of the first slot S1 (such as Figure 5 The Y direction) is orthogonal to the extension direction of the third portion T13 of the first feeding line T1 (eg Figure 5 The X direction), the extension direction of the long axis of the second slot S2 (such as Figure 5 The X direction) is orthogonal to the extension direction of the third portion T23 of the second feeding line T2 (eg Figure 5 Y direction).

[0053] Figure 6 : is an S parameter diagram of the antenna structure 10 according to an embodiment of the present invention. The horizontal axis represents the operating frequency (GHz), and the vertical axis represents the S parameter (dB). Figure 6 From the parameters S11 and S22, it can be seen that when the antenna structure 10 is fed by the first feed signal F1 and the second feed signal F2 at the same time, the operating frequency band of the antenna structure 10 below -10dB (the frequency band that achieves the impedance matching condition) can be covered between 13.69GHz and 15.24GHz. Therefore, the antenna structure 10 is suitable for broadband operation in the low-orbit satellite system 1. In addition, according to Figure 6From the S21 parameter, it can be seen that at frequencies between 13.75 GHz and 14.50 GHz, the isolation between the first feed signal F1 and the second feed signal F2 can be lower than -20 dB, which can meet the actual application requirements of the low-orbit satellite system 1. In addition, from the measurement results, it can be seen that when operating at 14 GHz, the measured antenna gain exceeds 7 dBi (the measured value is 7.2 dBi).

[0054] Figure 7 is a schematic diagram of the structure of a bandpass filter 30 according to an embodiment of the present invention. The bandpass filter 30 includes a substrate 31 and two step impedance resonators 32 symmetrically arranged on an upper surface 31U of the substrate 31, and each of the step impedance resonators 32 is an open loop resonator (Open Loop Ring Resonator, OLR). Specifically, the two step impedance resonators 32 are arranged on the upper surface 31U of the substrate 31 at intervals, and the two step impedance resonators 32 are symmetrical. The two step impedance resonators 32 are made of metal material, in other words, the two step impedance resonators 32 are metal microstrip lines (Microstrip).

[0055] The substrate 31 includes a liquid crystal polymer material. Since the liquid crystal polymer material has good anti-hygroscopicity, it has good environmental tolerance and is not easily affected by the environment (such as rain, etc.). It is convenient to use as a car-mounted product and is suitable for being placed on the roof for use in wilderness areas with poor signal.

[0056] In some embodiments, the substrate 31 may be a flexible substrate containing liquid crystal polymer material to provide a bending function. In some embodiments, the bandpass filter 30 may be directly designed in a printed circuit and formed on the substrate 31 at one time without the need for additional processes to make components. In some embodiments, the bandpass filter 30 may be covered with a liquid crystal polymer material protective layer to protect the bandpass filter 30.

[0057] Each of the two step impedance resonators 32 is a three-step step impedance resonator (SIR), including two first impedance segments 321, two second impedance segments 322, a third impedance segment 323, and an input-output terminal 324 connected to the third impedance segment 323. The third impedance segment 323 is connected between the two second impedance segments 322. One of the two first impedance segments 321 is connected to one of the two second impedance segments 322, and the other of the two first impedance segments 321 is connected to the other of the two second impedance segments 322. The two first impedance segments 321 are adjacent to each other but do not contact each other. The input-output terminal 324 is used to transmit signals.

[0058] In an embodiment of the present invention, a signal to be filtered is input from an input / output terminal 324 of one of the two stepped impedance resonators 32 to one of the two stepped impedance resonators 32, and then the filtered signal is output from the other of the two stepped impedance resonators 32 to the input / output terminal 324 of the other of the two stepped impedance resonators 32, so as to provide the filtered signal to other external devices (e.g., the up / down converter 40).

[0059] In the embodiment of the present invention, the first impedance segment 321, the second impedance segment 322 and the third impedance segment 323 are rectangular. The impedance of each of the two first impedance segments 321 is less than the impedance of each of the two second impedance segments 322, and the impedance of the third impedance segment 323 is less than the impedance of each of the two second impedance segments 322. The line width (line width) of each of the two first impedance segments 321 is greater than the line width of each of the two second impedance segments 322, and the line width of the third impedance segment 323 is greater than the line width of each of the two second impedance segments 322.

[0060] Specifically, the impedance of the stepped impedance resonator 32 of the embodiment of the present invention is designed as follows: from the center (the second impedance segment 322) to the outside, the impedance is large to small. Such an impedance design can control the frequency-doubling passband to be away from the main passband. However, the impedance portion with a low impedance value (such as the first impedance segment 321 and the third impedance segment 323) will require a larger width (for example, line width), and a larger line width design is not easy and will occupy more space. In order to reduce the size of the stepped impedance resonator 32, the stepped impedance resonator 32 of the embodiment of the present invention designs the first impedance segment 321, the second impedance segment 322 and the third impedance segment 323 to form a C-shaped coupling structure, which can reduce the space occupied by the stepped impedance resonator 32 and reduce the interference of parasitic capacitance.

[0061] Generally speaking, the existing stepped impedance resonator is mainly formed by a high impedance segment and two low impedance segments, and its configuration uses a design structure with a line width of "fat, thin, fat" (Note: the description of fat or thin corresponds to the line width), and in the design of the existing stepped impedance resonator, its resonance frequency can be determined by adjusting the impedance ratio and the electron length ratio. Relatively speaking, the configuration of one of the two first impedance segments 321, one of the two second impedance segments 322, the third impedance segment 323, the other of the two second impedance segments 322, and the other of the two first impedance segments 321 in the three-stage stepped impedance resonator 32 of the bandpass filter 30 uses a design structure with a line width segment of "fat, thin, fat, thin, fat". Compared with the existing stepped impedance resonator using a design structure with a line width segment of fat, thin, fat, the size of the three-stage stepped impedance resonator 32 of the present invention is reduced by 40%, and the matching is better.

[0062] In other embodiments of the present invention, the bandpass characteristics of the bandpass filter 30 can also be adjusted by adjusting the line width of at least one of the two first impedance segments 321, the two second impedance segments 322, and the third impedance segment 323 of each of the two first impedance segments 321, so as to provide the passband center frequency required by the user. In other words, Figure 7 The line width ratio of the two first impedance segments 321 , the two second impedance segments 322 and the third impedance segment 323 of each of the two first impedance segments 321 shown can be adjusted as long as each of the two stepped impedance resonators 32 still maintains a design structure using a line width segmentation of “fat-thin-fat-thin-fat”.

[0063] The characteristic impedance of the input / output terminal 324 is 50 ohms to achieve impedance matching. The input / output terminal 324 uses a transmission line in the form of a fan-shaped gradient line to feed the signal, so that the impedance discontinuity of the 50 ohm impedance transfer to the bandpass filter 30 is reduced, making its signal flatness better.

[0064] On the one hand, the input and output end 324 adopts a fan-shaped gradient line form to suppress high-frequency stop band (tripling frequency) / noise, greatly improving the suppression effect of stop band noise. On the other hand, the input and output end 324 adopts a fan-shaped gradient line form to facilitate users to adjust the parameters of the fan-shaped structure (for example, the radius) according to needs.

[0065] Specifically, the input-output end 324 is a fan-shaped structure, and the area of ​​the fan-shaped structure gradually increases as it moves away from the third impedance section 323. The design of the narrowest width of the fan-shaped structure, the radius length of the fan-shaped structure, and the arc length of the fan-shaped structure will affect the performance of the input-output end 324 in suppressing high-frequency stop band (tripling frequency) / noise. The input-output end 324 also adopts a zero-degree feeding method to generate a transmission zero point.

[0066] Each of the two stepped impedance resonators 32 has a hollow area 325 inside, and the hollow area 325 is connected to an opening 326. The opening 326 of one of the two stepped impedance resonators 32 is opposite to the opening 326 of the other of the two stepped impedance resonators 32. In other words, the stepped impedance resonator 32 adopts an open circuit resonator design. Further, the hollow area 325 of one of the two stepped impedance resonators 32 is roughly in the shape of a "convex" character, and the hollow area 325 of the other of the two stepped impedance resonators 32 is roughly in the shape of a "convex" character in the opposite direction.

[0067] On the one hand, the two first impedance segments 321, the two second impedance segments 322 and the third impedance segment 323 of each of the two stepped impedance resonators 32 form a C-shaped coupling structure. On the other hand, the hollow area 325 inside each of the two stepped impedance resonators 32 uses a T-shaped excitation line structure to enhance the coupling effect, so that the coupling effect of the tail of the two C-shaped coupling structures is enhanced.

[0068] The bandpass filter 30 further includes a metal ground plane disposed on the lower surface 31L of the substrate 31. In other words, the lower surface 31L of the substrate 31 is a metal ground plane. The metal ground plane can generate a transmission zero point in the bandpass filter 30, improve the passband suppression capability of the bandpass filter 30, and improve the passband characteristics of the bandpass filter 30.

[0069] Figure 8 : is an S parameter diagram of the bandpass filter 30 according to an embodiment of the present invention. The horizontal axis represents the operating frequency (GHz), and the vertical axis represents the S parameter (dB). Figure 8 From the S11 parameter, it can be seen that the operating frequency band of the bandpass filter 30 below -3dB can be covered between 13.35GHz and 14.67GHz. Therefore, the bandpass filter 30 is suitable for broadband operation of the low-orbit satellite system 1. Figure 8 From the S21 parameter, it can be seen that the insertion loss of the bandpass filter 30 at the passband (for example, at 13.9803 GHZ) is -1.79 dB, that is, a lower insertion loss is achieved within its passband, which can meet the actual application requirements of the low-orbit satellite system 1, and by Figure 8 The presented signal has good flatness.

[0070] Please go back Figure 1 , the substrate of each of the beamforming chip 20, the up / down converter 40 and the digital signal processor 50 includes a liquid crystal polymer material. In some embodiments, the substrate of each of the beamforming chip 20, the up / down converter 40 and the digital signal processor 50 can adopt a soft substrate containing a liquid crystal polymer material to provide a bending function. On the one hand, because the liquid crystal polymer material has good anti-hygroscopicity, it has good environmental tolerance and is not easily affected by the environment (such as rain, etc.), which is convenient to use as a vehicle-mounted product and is suitable for being placed on the roof for use in places with poor signals in the wilderness. On the other hand, the beamforming chip 20 requires a multi-stage power divider, and line loss is particularly important. The liquid crystal polymer material has the characteristics of low loss and can improve the transmission loss. The transmission loss does not exceed -1.5dB.

[0071] Fig. 9 : is an S parameter diagram of a low-orbit satellite system 1 according to an embodiment of the present invention. The horizontal axis represents the operating frequency (GHz), and the vertical axis represents the S parameter (dB). Fig. 9 From the S11 and S22 parameters, it can be seen that the operating frequency band of the low-orbit satellite system 1 below -10dB (the frequency band that achieves the impedance matching condition) can be covered between 13.65GHz and 15.30GHz. Therefore, the low-orbit satellite system 1 is suitable for broadband operation of the low-orbit satellite system 1. In addition, according to Fig. 9 From the S21 parameter, it can be seen that at frequencies between 12.56 GHz and 16.74 GHz, the isolation can be lower than -40 dB. Such a high isolation effect is sufficient to meet the actual application requirements of the low-orbit satellite system 1.

[0072] In summary, the present invention proposes a low-orbit satellite system, which is composed of an antenna structure, a beamforming chip, a bandpass filter, a frequency converter and a digital signal processor. The substrates of the above components all contain liquid crystal polymer materials. Since liquid crystal polymer materials have good anti-hygroscopicity, they have good environmental tolerance, and liquid crystal polymer materials have the characteristics of low loss, which can improve transmission loss. The antenna structure adopts a double-layer circular patch antenna design to realize a dual-polarization antenna with dual coupling feed. The openings on the upper surface and the openings on the lower surface of the grounding layer of the antenna structure adopt a staggered hole design, which can improve the process yield of the antenna structure and enhance the isolation of the antenna structure. The grounding layer of the antenna structure also applies slots near the openings on its upper surface, so that the antenna structure has a broadband effect and the isolation of the antenna structure is as high as -20dB. The configuration of the step impedance resonator of the bandpass filter uses a design structure with a line width segment of "fat, thin, fat, thin, fat", which is conducive to reducing the size and better matching.

[0073] The features of several embodiments are summarized above, so that those skilled in the art can better understand the aspects of the present invention. Those skilled in the art should understand that they can easily use the present invention as a basis to design or modify other processes and structures to achieve the same goals and / or achieve the same advantages as the embodiments introduced herein. Those skilled in the art should also understand that these equivalent constructions do not depart from the spirit and scope of the present invention, and they can make various changes, substitutions and modifications without departing from the spirit and scope of the present invention.

[0074]

Explanation of symbols

[0075] 1: Low Earth Orbit Satellite System

[0076] 10: Antenna structure

[0077] 20: Beamforming Chip

[0078] 30: Bandpass filter

[0079] 31:Substrate

[0080] 31L,300L: Bottom surface

[0081] 31U,300U: Top surface

[0082] 32: Stepped Impedance Resonator

[0083] 40: frequency converter

[0084] 50: Digital Signal Processor

[0085] 100: Upper patch antenna

[0086] 200: Lower patch antenna

[0087] 300: Ground layer

[0088] 321: First impedance section

[0089] 322: Second impedance segment

[0090] 323: The third impedance section

[0091] 324: Input and output

[0092] 325: Hollow Area

[0093] 326: Opening

[0094] 400: Transmission line layer

[0095] 500: first substrate

[0096] 600: Air layer

[0097] 700: Second substrate

[0098] 800: The third substrate

[0099] F1: First feed signal

[0100] F2: Second feed signal

[0101] L1: The first opening

[0102] L2: The second lower opening

[0103] P1: First feeding point

[0104] P2: Second feeding point

[0105] S1: First slot

[0106] S2: Second slot

[0107] T1: First feed line

[0108] T2: Second feeding line

[0109] T11, T21: Part 1

[0110] T12, T22: Part 2

[0111] T13, T23: Part 3

[0112] U1: First upper opening

[0113] U2: Second upper opening

[0114] X,Y,Z: direction.

Claims

1. An antenna structure, characterized in that: include: Upper patch antenna; a lower patch antenna, comprising a first feeding point and a second feeding point, wherein the upper patch antenna and the lower patch antenna have a circular shape, and an area of ​​the upper patch antenna is smaller than an area of ​​the lower patch antenna; a ground layer, wherein the lower patch antenna is located between the upper patch antenna and the ground layer; a transmission line layer, wherein the ground layer is located between the lower patch antenna and the transmission line layer; a first feeding line, passing through the ground layer and coupled between the transmission line layer and the first feeding point of the lower patch antenna; and a second feeding line, passing through the ground layer and coupled between the transmission line layer and the second feeding point of the lower patch antenna; The first feeding line and the second feeding line are orthogonal to each other, and each of the first feeding line and the second feeding line comprises: A first portion is located between the lower patch antenna and the ground layer and is perpendicular to an extending direction of the ground layer; A second portion is located between the ground layer and the transmission line layer and is perpendicular to the extension direction; and The third portion is located on the ground layer and parallel to the extending direction, wherein the third portion is coupled between the first portion and the second portion.

2. The antenna structure according to claim 1, characterized in that: Also includes: A first substrate, located between the upper patch antenna and the lower patch antenna; an air layer, located between the first substrate and the lower patch antenna; a second substrate, located between the lower patch antenna and the ground layer; and A third substrate, located between the ground layer and the transmission line layer; Each of the first substrate, the second substrate and the third substrate comprises a liquid crystal polymer material.

3. The antenna structure according to claim 1, characterized in that: The ground layer has an upper surface close to the lower patch antenna and a lower surface away from the lower patch antenna, wherein the ground layer includes a first upper opening and a second upper opening located on the upper surface and a first lower opening and a second lower opening located on the lower surface, wherein the first portion of the first feed line is coupled to the third portion of the first feed line through the first upper opening, wherein the first portion of the second feed line is coupled to the third portion of the second feed line through the second upper opening, wherein the second portion of the first feed line is coupled to the third portion of the first feed line through the first lower opening, wherein the second portion of the second feed line is coupled to the third portion of the second feed line through the second lower opening, wherein vertical projections of the first upper opening and the first lower opening on the ground layer do not overlap with each other, and wherein vertical projections of the second upper opening and the second lower opening on the ground layer do not overlap with each other.

4. The antenna structure according to claim 1, characterized in that: The first feeding line and the second feeding line receive a first feeding signal and a second feeding signal respectively, wherein an extending direction of the third portion of the first feeding line is orthogonal to an extending direction of the third portion of the second feeding line.

5. The antenna structure according to claim 3, characterized in that: The grounding layer also includes a first slot and a second slot that penetrate the grounding layer, wherein the first slot is adjacent to the first upper opening and the first upper opening is located between the first slot and the first lower opening, wherein the second slot is adjacent to the second upper opening and the second upper opening is located between the second slot and the second lower opening.

6. The antenna structure according to claim 5, characterized in that: The first slot hole and the second slot hole have a rectangular shape or an elliptical shape, wherein when the first slot hole and the second slot hole have a rectangular shape, the extension direction of the long side of the first slot hole is orthogonal to the extension direction of the third portion of the first feed line and the extension direction of the long side of the second slot hole is orthogonal to the extension direction of the third portion of the second feed line, wherein when the first slot hole and the second slot hole have an elliptical shape, the extension direction of the long axis of the first slot hole is orthogonal to the extension direction of the third portion of the first feed line and the extension direction of the long axis of the second slot hole is orthogonal to the extension direction of the third portion of the second feed line.

7. A low-orbit satellite system, characterized in that: include: An antenna structure for receiving a first radio frequency signal or sending a second radio frequency signal; a beamforming chip, coupled to the antenna structure to perform beamforming on the first radio frequency signal; a bandpass filter, coupled to the beamforming chip to bandpass filter the first radio frequency signal; an up-down converter, coupled to the bandpass filter to down-convert the first RF signal into a first baseband signal, wherein the up-down converter is further configured to up-convert a second baseband signal into the second RF signal; and a digital signal processor, coupled to the up / down converter to perform digital signal processing on the first baseband signal, wherein the digital signal processor is further configured to generate the second baseband signal; The antenna structure comprises: Upper patch antenna; a lower patch antenna, comprising a first feeding point and a second feeding point, wherein the upper patch antenna and the lower patch antenna have a circular shape, and an area of ​​the upper patch antenna is smaller than an area of ​​the lower patch antenna; a ground layer, wherein the lower patch antenna is located between the upper patch antenna and the ground layer; a transmission line layer, wherein the ground layer is located between the lower patch antenna and the transmission line layer; A first feeding line, passing through the ground layer and coupled between the transmission line layer and the first feeding point of the lower patch antenna; and a second feeding line, passing through the ground layer and coupled between the transmission line layer and the second feeding point of the lower patch antenna; The first feeding line and the second feeding line are orthogonal to each other, and each of the first feeding line and the second feeding line comprises: A first portion is located between the lower patch antenna and the ground layer and is perpendicular to an extending direction of the ground layer; A second portion is located between the ground layer and the transmission line layer and is perpendicular to the extension direction; and The third portion is located on the ground layer and parallel to the extending direction, wherein the third portion is coupled between the first portion and the second portion.

8. The low-orbit satellite system according to claim 7, characterized in that: The bandpass filter includes a substrate, two stepped impedance resonators symmetrically arranged on the upper surface of the substrate, and a metal ground plate arranged on the lower surface of the substrate, wherein each of the two stepped impedance resonators is an open-circuit ring resonator, wherein the substrate of the bandpass filter includes a liquid crystal polymer material, wherein the substrate of each of the beamforming chip, the up / down converter and the digital signal processor includes a liquid crystal polymer material.

9. The low-orbit satellite system according to claim 8, characterized in that: Each of the two stepped impedance resonators is a three-step stepped impedance resonator, including two first impedance segments, two second impedance segments, a third impedance segment, and an input-output end connected to the third impedance segment, wherein the third impedance segment is connected between the two second impedance segments, wherein one of the two first impedance segments is connected to one of the two second impedance segments, wherein the other of the two first impedance segments is connected to the other of the two second impedance segments, and wherein the two first impedance segments are adjacent to each other but do not contact each other.

10. The low-orbit satellite system according to claim 9, characterized in that: The impedance of each of the two first impedance segments is smaller than the impedance of each of the two second impedance segments, wherein the impedance of the third impedance segment is smaller than the impedance of each of the two second impedance segments, wherein the line width of each of the two first impedance segments is larger than the line width of each of the two second impedance segments, wherein the line width of the third impedance segment is larger than the line width of each of the two second impedance segments.

11. The low-orbit satellite system according to claim 9, characterized in that: The two first impedance segments, the two second impedance segments and the third impedance segment of each of the two stepped impedance resonators form a C-shaped coupling structure, wherein the characteristic impedance of the input and output ends is 50 ohms, and the input and output ends use transmission lines in the form of fan-shaped gradient lines to feed signals.

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