A dual-frequency four-arm helical antenna for low-orbit satellite communications

Abstract

The present invention discloses a dual-frequency four-arm helical antenna for low-orbit satellite communication, including a direct-feed helical unit, a coupled-feed helical unit, an antenna reflective base plate and a feeding network; the tops of the direct-feed helical unit and the coupled-feed helical unit are open-circuited and installed on the antenna reflective base plate in a coaxial nested manner; the coupled-feed helical unit is connected to the grounding point of the coupled-feed helical arm; the direct-feed helical unit is connected to the feeding point of the direct-feed helical arm; the feeding network is installed on the antenna reflective base plate, connected to multiple direct-feed helical arm feeding points, and is used to feed multiple direct-feed helical arms. The present invention simultaneously satisfies the dual-band operation of the four-arm helical antenna, and both dual-bands have approximately the same heart-shaped radiation pattern, so that the low-orbit satellite can have the best effect in both receiving and transmitting when communicating at a low elevation angle of the terminal.

Description

Technical Field

[0001] The present invention relates to the field of satellite communication technology, and in particular to a dual-frequency four-arm helical antenna applied to low-orbit satellite communication. Background Art

[0002] With the continuous development and iteration of satellite communication technology, low-orbit satellite communication has received more and more attention and its development has accelerated. Unlike traditional high-orbit satellites or synchronous orbit satellites, low-orbit satellite communications require ground terminal antennas to have higher gain near low elevation angles to meet the needs of the ground-to-space link. The four-arm helical antenna is easy to achieve a heart-shaped pattern, that is, the high-elevation angle part of the pattern is slightly concave, and the medium and low elevation angle parts are convex, which is more in line with the application needs of low-orbit satellite communications. On the other hand, the reception and transmission of low-orbit satellite communications are two independent frequency bands, and the commonly used wide-beam four-arm helical antenna is a resonant antenna with a bandwidth of about 5%-8%, which is difficult to meet the dual-band working requirements of low-orbit satellite communications. In addition, in order to have the best communication effect in both the reception and transmission frequency bands, low-orbit satellites require antennas to have approximately the same heart-shaped pattern in both frequency bands.

[0003] In order to meet the requirements of the quadrifilar helix antenna's heart-shaped radiation pattern and dual-frequency operation, many scholars have done a lot of targeted work: for example, reference [1] "Dual band quadrifilar helix antenna" uses an LC resonant circuit to add a spiral arm to achieve dual-frequency operation; reference [2] "Broadband folded quadrifilar helical antenna" uses an inverted U-shaped spiral arm to achieve dual-frequency operation; reference [3] "Dual-band shaped-pattern quadrifilar helix antenna" adds short branches to the spiral arm and achieves dual-frequency operation by increasing the resonant path of the monopole type spiral arm. Although the above methods can achieve dual-frequency operation of the quadrifilar helix antenna, they cannot achieve a nearly identical heart-shaped radiation pattern in both frequency bands at the same time, which is what low-orbit satellite communications value.

[0004] It is difficult for the existing technology to simultaneously meet the requirements that the quadrifilar helical antenna operates in dual frequency bands and both frequency bands have approximately the same heart-shaped radiation pattern. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the reception and transmission of low-orbit satellite communications are two independent frequency bands respectively. The commonly used wide-beam four-arm helical antenna is difficult to meet the dual-band working requirements of low-orbit satellite communications. In order to have the best communication effect in both the reception and transmission frequency bands, the antenna is required to have approximately the same heart-shaped radiation pattern in the reception and transmission frequency bands. However, the prior art is difficult to simultaneously meet the requirements that the four-arm helical antenna operates in dual bands and both frequency bands have approximately the same heart-shaped radiation pattern. The purpose is to provide a dual-band four-arm helical antenna used for low-orbit satellite communications to solve the above problems.

[0006] The present invention is achieved through the following technical solutions:

[0007] A dual-frequency four-arm helical antenna for low-orbit satellite communications, comprising a direct-feed helical unit, a coupled-feed helical unit, an antenna reflector bottom plate and a feeding network;

[0008] The tops of the direct feeding helical unit and the coupled feeding helical unit are open-circuited and are mounted on the antenna reflective bottom plate in a coaxial nesting manner;

[0009] The coupling feed helical unit comprises a plurality of coupling feed helical arms, the antenna reflection bottom plate is provided with a plurality of coupling feed helical arm grounding points which are equal in number to the plurality of coupling feed helical arms, and the plurality of coupling feed helical arms are respectively connected one by one to the plurality of coupling feed helical arm grounding points;

[0010] The direct-feeding helical unit comprises a plurality of direct-feeding helical arms, the antenna reflection base plate is provided with a plurality of direct-feeding helical arm feeding points equal in number to the plurality of direct-feeding helical arms, and the plurality of direct-feeding helical arms are respectively connected one by one to the plurality of direct-feeding helical arm feeding points;

[0011] The feeding network is installed on the antenna reflection bottom plate and connected to a plurality of direct-feed spiral arm feeding points, and is used for feeding the plurality of direct-feed spiral arms.

[0012] The present invention realizes the dual-frequency working mode of the quadrifilar helical antenna as a whole by combining the direct-feed quadrifilar helical and the coupled-feed quadrifilar helical. By setting the inner spiral winding radius smaller than the outer spiral winding radius and the inner spiral rise angle smaller than the outer spiral rise angle, the dual-frequency quadrifilar helical antenna has the requirement of having approximately the same heart-shaped radiation pattern in both high and low frequency bands. The present invention satisfies the dual-frequency band working of the quadrifilar helical antenna, and both frequency bands have approximately the same heart-shaped radiation pattern, so that the low-orbit satellite can achieve the best effect in both reception and transmission when communicating at a low elevation angle of the terminal.

[0013] Further, the coupling feed spiral unit includes a plurality of coupling feed spiral arms, the antenna reflection base plate is provided with a plurality of coupling feed spiral arm grounding points equal to the number of the plurality of coupling feed spiral arms, and the plurality of coupling feed spiral arms are respectively connected one by one to the plurality of coupling feed spiral arm grounding points. Specifically, the coupling feed spiral unit includes four coupling feed spiral arms, the antenna reflection base plate is provided with four coupling feed spiral arm grounding points, the four coupling feed spiral arms are respectively connected one by one to the four coupling feed spiral arm grounding points, and the phases of the four coupling feed spiral arm grounding points are sequentially different by ninety degrees.

[0014] Further, the direct-fed spiral unit includes a plurality of direct-fed spiral arms, the antenna reflection base plate is provided with a plurality of direct-fed spiral arm feeding points equal to the number of the plurality of direct-fed spiral arms, and the plurality of direct-fed spiral arms are respectively connected one by one with the plurality of direct-fed spiral arm feeding points. Specifically, the direct-fed spiral unit includes four direct-fed spiral arms, the antenna reflection base plate is provided with four direct-fed spiral arm feeding points, the four direct-fed spiral arms are respectively connected one by one with the four direct-fed spiral arm feeding points, the four direct-fed spiral arm feeding points are connected to a feeding network, and the phases of the four direct-fed spiral arm feeding points differ by ninety degrees in sequence; the feeding network is used to provide four RF signals with equal amplitudes and phases differing by ninety degrees in sequence to the four direct-fed spiral arm feeding points.

[0015] Furthermore, the direct feeding spiral unit is arranged in the outer circle low frequency working area, and the coupled feeding spiral unit is arranged in the inner circle high frequency working area.

[0016] Furthermore, the coupling feeding spiral unit is arranged in the outer circle low frequency working area, and the direct feeding spiral unit is arranged in the inner circle high frequency working area.

[0017] A group of four-arm spirals working in a lower frequency band is placed on the outside of the nested combination, and can be a directly fed spiral unit or a coupled fed spiral unit; the four-arm spirals working in a higher frequency band are placed on the inside of the nested combination. If a directly fed spiral unit is set on the outside of the nested combination, a coupled fed spiral unit is set on the inside of the nested combination; if a coupled fed spiral unit is set on the outside of the nested combination, a directly fed spiral unit is set on the inside of the nested combination.

[0018] Furthermore, the direct-feed helical unit adopts one of a high-frequency dielectric thin substrate printed four-arm helical antenna, a spiral metal antenna, a spiral metal rod antenna, and a hollow dielectric loaded thin film printed four-arm helical antenna; the coupled-feed helical unit is made of the same material as the direct-feed helical unit.

[0019] Furthermore, the direct-feed helical unit and the coupled-feed helical unit both adopt a high-frequency dielectric thin substrate printed quadrifilar helical antenna; the dual-frequency quadrifilar helical antenna applied to low-orbit satellite communication also includes an outer supporting dielectric thin substrate and an inner supporting dielectric thin substrate;

[0020] The outer supporting dielectric thin substrate and the inner supporting dielectric thin substrate are mounted on the antenna reflective bottom plate in a coaxial nesting manner, and the inner supporting dielectric thin substrate is located on the inner side of the outer supporting dielectric thin substrate;

[0021] The four directly fed spiral arms are wound in the same direction on the outer supporting dielectric thin substrate, and the four coupled fed spiral arms are wound in the same direction on the inner supporting dielectric thin substrate, wherein the winding direction of the four directly fed spiral arms is the same as the winding direction of the four coupled fed spiral arms.

[0022] Furthermore, the direct-feed helical unit and the coupled-feed helical unit are both right-hand circularly polarized four-arm helical antennas.

[0023] Furthermore, the direct-feed helical unit and the coupled-feed helical unit are both left-hand circularly polarized four-arm helical antennas.

[0024] Furthermore, the direct-feed helical unit and the coupled-feed helical unit both operate in a three-quarter wavelength mode. The direct-feed helical unit and the coupled-feed helical unit can operate in a half wavelength mode or a three-quarter wavelength mode, preferably in a three-quarter wavelength mode.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] The present invention provides a dual-frequency four-arm helical antenna for low-orbit satellite communications, which simultaneously meets the dual-band operation of the four-arm helical antenna, and both of the dual-bands have approximately the same heart-shaped radiation pattern, so that the low-orbit satellite can achieve the best reception and transmission effects when communicating at a low elevation angle of the terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0028] Figure 1 This is a general diagram of a dual-frequency four-arm helical antenna solution of a preferred embodiment of the present invention;

[0029] Figure 2A schematic diagram of a quadrifilar helical antenna in a high-frequency working area of ​​an inner circle of a dual-frequency quadrifilar helical antenna component expansion diagram of a preferred embodiment of the present invention;

[0030] Figure 3 A schematic diagram of a four-arm helical antenna in a low-frequency working area of ​​an outer circle of a dual-frequency four-arm helical antenna component expansion diagram of a preferred embodiment of the present invention;

[0031] Figure 4 This is a diagram of a reflective base plate and a feeding network of a dual-frequency four-arm helical antenna according to a preferred embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the circuit of the feeding end of a dual-frequency four-arm helical antenna according to a preferred embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of the ground terminal circuit of a dual-frequency four-arm helical antenna according to a preferred embodiment of the present invention;

[0034] Figure 7 It is a schematic diagram of the circular polarization gain pattern of a traditional dual-band four-arm helical antenna;

[0035] Figure 8 It is a schematic diagram of the circular polarization gain pattern of the dual-frequency four-arm helical antenna of the present invention.

[0036] Marks and corresponding parts names in the attached drawings:

[0037] 1-direct feeding spiral arm, 2-coupled feeding spiral arm, 3-external supporting dielectric thin substrate, 4-inner supporting dielectric thin substrate, 5-antenna reflection base plate, 6-outer spiral arm installation position, 7-inner spiral arm installation position, 8-direct feeding spiral arm feeding point, 9-coupled feeding spiral arm grounding point, 10-total feeding port. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0039] Example 1

[0040] The four-arm helix in this embodiment 1 adopts spiral metal wire. The dual-band four-arm helix antenna scheme of the embodiment of the present invention includes three parts: a group of directly fed metal wire four-arm helices, a group of coupled fed metal wire four-arm helices, an antenna reflection base plate and its accompanying feeding network.

[0041] The directly fed metal wire four-arm spiral and the coupled fed metal wire four-arm spiral are open-circuited at the top and are installed on the antenna reflection bottom plate in a coaxial nested manner; the directly fed metal wire four-arm spiral is arranged in the outer circle low-frequency working area, and the coupled fed metal wire four-arm spiral is arranged in the inner circle high-frequency working area.

[0042] The antenna reflector base plate is a double-sided copper-filled circular PCB board, and four coupling spiral arm grounding points and four direct-feed spiral arm feeding points are reserved on the base plate surface. The four coupling-feed spiral arms 2 are connected to the four coupling-feed spiral arm grounding points one by one, and the four coupling-feed spiral arm grounding points are sequentially phase-shifted by ninety degrees; the four direct-feed spiral arms 1 are connected to the four direct-feed spiral arm feeding points one by one, and the four direct-feed spiral arm feeding points are connected to the feeding network, and the four direct-feed spiral arm feeding points are sequentially phase-shifted by ninety degrees; the feeding network is used to provide four RF signals with equal amplitudes and phases sequentially shifted by 90 degrees for the four direct-feed spiral arm feeding points.

[0043] In this embodiment, both the directly-fed metal wire four-arm helix and the coupled-fed metal wire four-arm helix are right-hand circularly polarized four-arm helix antennas, and both operate in a three-quarter wavelength mode.

[0044] Example 2

[0045] The difference between the second embodiment and the first embodiment is that the four-arm spiral in the first embodiment uses a spiral metal wire, while the four-arm spiral in the second embodiment uses a high-frequency dielectric thin substrate printed four-arm spiral. Figure 1 and Figure 2 As shown, a dual-frequency four-arm helical antenna solution applied to low-orbit satellite communications is used as an example to illustrate.

[0046] Figure 1 The overall diagram of the dual-band four-arm helical antenna scheme is given. Figure 2 and Figure 3 The following is a diagram showing the expansion of the components of a dual-frequency quadrifilar helical antenna, where: Figure 2 This is a schematic diagram of the inner circle high frequency working area four-arm helical antenna. Figure 3 Schematic diagram of the four-arm helical antenna in the outer low-frequency working area. Figure 4 The reflection base plate and feeding network diagram of the dual-frequency quadrifilar helical antenna are given. Figure 5 The circuit schematic diagram of the feeding end of the dual-frequency four-arm helical antenna is given; Figure 6 The circuit schematic diagram of the ground terminal of the dual-frequency four-arm helical antenna is given; Figure 7 A schematic diagram of the circular polarization gain pattern of a traditional dual-band four-arm helical antenna is given; Figure 8 A schematic diagram of the circular polarization gain pattern of the dual-frequency four-arm helical antenna of the present invention is given.

[0047] from Figure 4 It can be seen that the low-frequency radiation pattern and high-frequency radiation pattern of the traditional dual-frequency four-arm helical antenna are inconsistent: when the high frequency presents a heart-shaped radiation pattern suitable for low-orbit satellite communications, the low frequency does not present a heart-shaped radiation pattern; when the low frequency presents a heart-shaped radiation pattern suitable for low-orbit satellite communications, the high-elevation angle part of the high-frequency radiation pattern will become too deep. Both situations are not conducive to low-orbit satellites to achieve the best reception and transmission effects. The dual-frequency four-arm helical antenna of the present invention solves the above-mentioned problems of the traditional dual-frequency four-arm helical antenna, and can have approximately the same heart-shaped radiation pattern in both the receiving and transmitting frequency bands, such as Figure 5 shown.

[0048] like Figure 1 As shown, the dual-band four-arm helical antenna solution of the embodiment of the present invention includes three parts: a group of directly fed printed four-arm helices, namely, directly fed helical arms 1; a group of coupled fed printed four-arm helices, namely, coupled fed helical arms 2, an antenna reflection base plate 5 and its accompanying feeding network.

[0049] In this embodiment 1, two groups of four-arm spirals are printed on the surfaces of two high-frequency dielectric thin substrates, specifically, as Figure 1-3 As shown, four direct-feed spiral arms 1 are printed on the outer supporting dielectric thin substrate 3, and four coupled-feed spiral arms 2 are printed on the inner supporting dielectric thin substrate 4. First, the high-frequency dielectric thin substrate is wrapped into a cylindrical tube. Since welding fixing points are reserved at the edge of the dielectric thin substrate, only solder is needed to fix the two high-frequency dielectric thin substrates into two cylindrical tubes. At this time, the spiral radiation arm is located outside the cylindrical tube.

[0050] Use solder to first connect the four spiral arms of the coupled-fed four-arm spiral and the four coupled-fed spiral arm grounding points of the antenna reflection floor, and then connect the four spiral arms of the directly-fed four-arm spiral and the four directly-fed spiral arm feeding points of the antenna reflection floor 5. From the perspective of structural reliability, several more welding fixing points can also be reserved on the surfaces of the two four-arm spiral cylinders. The antenna reflection base plate 5 is a double-sided copper-coated circular PCB board. Four coupled-fed spiral arm grounding points and four directly-fed spiral arm feeding points are reserved on the surface of the base plate. The feeding current amplitudes of the four directly-fed spiral arm feeding points are equal, and the phases differ by 90° respectively. The four directly-fed spiral arm feeding points are the four output ends of a four-phase chip (the chip output end and the corresponding feeding point are connected by a microstrip line). The specific phase change method is: according to Figure 4 Rotating counterclockwise, the port phase decreases by 90°. The input end of the four-phase chip is the total feed port 10 of the dual-frequency four-arm helical antenna.

[0051] This embodiment provides a right-handed circularly polarized dual-frequency four-arm helical antenna. The present invention can also be a left-handed circularly polarized dual-frequency four-arm helical antenna. The specific implementation method only needs to change the rotation direction of the spiral arm and the phase decreasing direction of the feeding network accordingly.

[0052] In this embodiment, a high-frequency dielectric thin substrate is used to print a four-arm spiral. The present invention can also use spiral metal wires, spiral metal rods, hollow dielectric loaded thin film printed four-arm spiral antennas, etc. The four-arm spiral antenna operates in three-quarter wavelength mode or half wavelength mode, and its length is approximately three-quarters or one-half of the wavelength of the medium at the corresponding environmental working frequency. The three-quarter wavelength mode is the preferred wavelength mode.

[0053] In the embodiment, the feeding network is implemented by a four-phase chip outputting four RF signals with equal amplitudes and phases that differ by 90 degrees. There are many specific forms of feeding networks that can be used in the present invention, including but not limited to a combination of a 3dB bridge and a phase delay line, a combination of a Wilkinson power divider and a phase delay line, etc. The core is that as long as the feeding network provides four signals with equal amplitudes and phases that differ by 90 degrees to feed the dual-frequency four-arm helical antenna mentioned in this patent, it is within the protection scope of the present invention.

[0054] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dual-frequency four-arm helical antenna for low-orbit satellite communications, characterized in that: It includes a direct feeding spiral unit, a coupled feeding spiral unit, an antenna reflection base plate and a feeding network; The tops of the direct feeding helical unit and the coupled feeding helical unit are open-circuited and are mounted on the antenna reflective bottom plate in a coaxial nested manner; the inner helical rise angle is smaller than the outer helical rise angle; The coupling feed spiral unit includes four coupling feed spiral arms, the antenna reflection bottom plate is provided with four coupling feed spiral arm grounding points, the four coupling feed spiral arms are respectively connected to the four coupling feed spiral arm grounding points one by one, and the phases of the four coupling feed spiral arm grounding points are sequentially different by ninety degrees; The direct-feed spiral unit comprises four direct-feed spiral arms, the antenna reflection bottom plate is provided with four direct-feed spiral arm feeding points, the four direct-feed spiral arms are respectively connected to the four direct-feed spiral arm feeding points one by one, the four direct-feed spiral arm feeding points are connected to the feeding network, and the four direct-feed spiral arm feeding points are sequentially phase-differed by 90 degrees; the feeding network is used to provide four radio frequency signals with equal amplitudes and sequentially phase-differed by 90 degrees for the four direct-feed spiral arm feeding points; the feeding network is installed on the antenna reflection bottom plate, and is used to provide four radio frequency signals with equal amplitudes and sequentially phase-differed by 90 degrees for the four direct-feed spiral arm feeding points; The direct feeding spiral unit is arranged in the outer circle low frequency working area, and the coupled feeding spiral unit is arranged in the inner circle high frequency working area.

2. The dual-frequency quadrifilar helical antenna for low-orbit satellite communications according to claim 1, characterized in that: The direct feeding spiral unit adopts one of a high frequency dielectric thin substrate printing four-arm spiral line, a spiral metal line, and a hollow dielectric loaded thin film printing four-arm spiral line; the coupled feeding spiral unit is made of the same material as the direct feeding spiral unit.

3. The dual-frequency quadrifilar helical antenna for low-orbit satellite communications according to claim 2, characterized in that: The direct feeding spiral unit and the coupled feeding spiral unit both adopt a high-frequency dielectric thin substrate to print four-arm spiral lines; The dual-frequency four-arm helical antenna applied to low-orbit satellite communications further comprises an outer supporting dielectric thin substrate (3) and an inner supporting dielectric thin substrate (4); The outer supporting dielectric thin substrate (3) and the inner supporting dielectric thin substrate (4) are mounted on the antenna reflection bottom plate (5) in a coaxial nesting manner, and the inner supporting dielectric thin substrate (4) is located on the inner side of the outer supporting dielectric thin substrate (3); The four direct-feeding spiral arms (1) are wound in the same direction on an outer supporting dielectric thin substrate (3), and the four coupled-feeding spiral arms (2) are wound in the same direction on an inner supporting dielectric thin substrate (4), wherein the winding direction of the four direct-feeding spiral arms (1) is the same as the winding direction of the four coupled-feeding spiral arms (2).

4. The dual-frequency quadrifilar helical antenna for low-orbit satellite communications according to claim 1, characterized in that: The direct-feed helical unit and the coupled-feed helical unit are both right-hand circularly polarized four-arm helical antennas.

5. The dual-frequency quadrifilar helical antenna for low-orbit satellite communications according to claim 1, characterized in that: The direct-feed helical unit and the coupled-feed helical unit are both left-hand circularly polarized four-arm helical antennas.

6. The dual-frequency quadrifilar helical antenna for low-orbit satellite communications according to claim 1, characterized in that: The direct-feed spiral unit and the coupled-feed spiral unit both operate in a three-quarter wavelength mode.

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