An ultra-wideband compact circularly polarized helical antenna

Abstract

The invention discloses an ultra-wideband compact circularly polarized helical antenna, comprising an antenna support, a double-arm helical line, a microstrip balun, a support plate and an SMA high-frequency electrical connector. The microstrip balun comprises a PCB board, a first coaxial feeder and a second coaxial feeder. The PCB board is inserted into the antenna support along the axial direction of the antenna support. The first coaxial feeder and the second coaxial feeder are respectively arranged on two side surfaces of the PCB board along the axial direction of the antenna support. The top end of the first helical line is connected to the top end of the first coaxial feeder, and the top end of the second helical line is connected to the top end of the second coaxial feeder. The support plate is fixedly installed on the bottom end of the PCB board. The SMA high-frequency electrical connector is installed on the support plate and is used for transmitting guided waves to the microstrip balun. The invention adopts a double-arm conical helical line plus an ultra-wideband microstrip balun to solve the problem of the demand for radiated circularly polarized electromagnetic waves within a wide frequency band. At the same time, the helical antenna has a small volume, a light weight, and a reliable and stable structure.

Description

Technical Field

[0001] The invention belongs to the field of antenna design, and in particular relates to an ultra-wideband compact circularly polarized helical antenna. Background Art

[0002] With the rapid development of satellite technology at home and abroad, the spectrum resources of traditional payloads are extremely tight, and the requirements for the development of ultra-wideband, lightweight, and miniaturized antennas are getting higher and higher, especially the requirements for circular polarization and high gain. Such antennas can be widely used in various payloads and platform systems, and can also be used in ground satellite communication systems. At present, microwave radiometer antennas used for satellites usually use waveguide slot array antennas and reflector antennas. The disadvantages are that the bandwidth is very narrow, the circular polarization bandwidth is even narrower, and the weight is large, which is not conducive to the lightweight requirements of satellites.

[0003] Domestic broadband microwave radiometer antennas usually use logarithmic periodic antennas, but they have obvious disadvantages: 1) The bandwidth is not wide enough, and an external 90° bridge is required to form circular polarization; 2) The horizontal size is relatively large, which is not very friendly to the increasingly smaller cabin surface area of ​​micro-satellites. The microwave radiometer antennas currently used abroad mostly use waveguide slot array antennas, which have the following disadvantages: 1) The weight is very large, which is not conducive to satellite lightweighting; 2) The circular polarization bandwidth is not good enough. Summary of the invention

[0004] The purpose of the present invention is to provide an ultra-wideband compact circularly polarized helical antenna, which has good impedance matching characteristics and circular polarization characteristics within a range of more than 5 times the frequency band, uses a microstrip balun to solve wide-band impedance matching and current balance, and uses a conical double-arm helical line to convert guided waves into electromagnetic waves that radiate freely in space, thereby solving the problem of being able to transmit and receive electromagnetic waves within a wide frequency band.

[0005] To solve the above problems, the technical solution of the present invention is:

[0006] An ultra-wideband compact circularly polarized helical antenna, comprising an antenna bracket, a double-arm helical line, a microstrip balun, a support plate and an SMA high-frequency electrical connector;

[0007] The antenna bracket is a conical cylinder with upper and lower openings, and the outer wall of the antenna bracket is provided with two spiral grooves extending from bottom to top;

[0008] The double-arm helical wire comprises a first helical wire and a second helical wire, which are respectively installed in the two helical grooves, and the bottom ends of the first helical wire and the second helical wire are both fixedly connected to the antenna bracket;

[0009] The microstrip balun includes a PCB board, a first coaxial feed line and a second coaxial feed line, the PCB board is inserted into the antenna bracket along the axial direction of the antenna bracket, the first coaxial feed line and the second coaxial feed line are respectively arranged on two side surfaces of the PCB board along the axial direction of the antenna bracket, the top end of the first helix is ​​connected to the top end of the first coaxial feed line, and the top end of the second helix is ​​connected to the top end of the second coaxial feed line;

[0010] The support plate is fixedly mounted on the bottom end of the PCB board;

[0011] The SMA high-frequency electrical connector is mounted on the support plate and is used to transmit the guided wave to the microstrip balun.

[0012] Preferably, it further comprises a fixing sleeve, which is embedded in the top end of the antenna bracket, and the fixing sleeve is provided with a fixing groove along the axial direction, and the top end of the PCB board is inserted into the fixing groove to fix the PCB.

[0013] Preferably, two slide grooves are symmetrically opened on the inner wall of the antenna bracket, and the edge of the PCB board is inserted into the slide groove to install the PCB board in the antenna bracket.

[0014] Preferably, the top end of the first helical wire is connected to the top end of the first coaxial feeder by welding, and the top end of the second helical wire is connected to the top end of the second coaxial feeder by welding.

[0015] Preferably, the bottom diameter of the antenna bracket is Φ270 mm, the top diameter is Φ18, and the helical pitch of the double-arm helical line is 33 mm.

[0016] Preferably, the fixing sleeve is made of polyimide.

[0017] Preferably, the support plate is made of polyimide.

[0018] Preferably, the antenna bracket is made of fiberglass.

[0019] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0020] 1) The present invention provides an ultra-wideband compact circularly polarized helical antenna, comprising an antenna bracket, a double-arm helical line, a microstrip balun, a support plate and an SMA high-frequency electrical connector. The microstrip balun comprises a PCB board, a first coaxial feeder and a second coaxial feeder. The PCB board is inserted into the antenna bracket along the axial direction of the antenna bracket. The first coaxial feeder and the second coaxial feeder are respectively arranged on two side surfaces of the PCB board along the axial direction of the antenna bracket. The top of the first helical line is connected to the top of the first coaxial feeder, and the top of the second helical line is connected to the top of the second coaxial feeder. The support plate is fixedly installed on the bottom end of the PCB board. The SMA high-frequency electrical connector is installed on the support plate and is used to transmit the guided wave to the microstrip balun. The present invention solves the problem of the demand for radiated circularly polarized electromagnetic waves within a wide bandwidth by using a double-arm conical helical line plus an ultra-wideband microstrip balun. At the same time, the helical antenna is small in size, light in weight, and has a reliable and stable structure. After testing, the ultra-wideband compact circularly polarized helical antenna of the present invention has a 3dB beam width of about ±80°, a maximum gain greater than 9dB, a front-to-back ratio better than 25dB, and an in-beam circular polarization axis ratio less than 3dB, which meets the needs of general satellites. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A structural diagram of an ultra-wideband compact circularly polarized helical antenna provided by an embodiment of the present invention;

[0022] Figure 2 A cross-sectional view of an ultra-wideband compact circularly polarized helical antenna provided by an embodiment of the present invention;

[0023] Figure 3 for Figure 1 The enlarged view of point A in the middle;

[0024] Figure 4 for Figure 1 The enlarged view of point B in the middle;

[0025] Figure 5 for Figure 1 A magnified view from another angle at the center A;

[0026] Figure 6 for Figure 1 A magnified view of another angle at B in the middle;

[0027] Figure 7 A gain pattern curve of an ultra-wideband compact circularly polarized helical antenna provided by an embodiment of the present invention;

[0028] Figure 8 An axial ratio pattern curve of an ultra-wideband compact circularly polarized helical antenna provided by an embodiment of the present invention;

[0029] Fig. 9A standing wave curve of an ultra-wideband compact circularly polarized helical antenna provided by an embodiment of the present invention.

[0030] Description of reference numerals:

[0031] 1: antenna bracket; 2: double-arm spiral line; 3: microstrip balun; 31: PCB board; 32: first coaxial feed line; 33: second coaxial feed line; 4: support plate; 5: SMA high-frequency electrical connector; 6: fixing sleeve. DETAILED DESCRIPTION

[0032] The advantages and features of the present invention will be more clearly understood from the following description and claims.

[0033] See also Figures 1 to 6 As shown, this embodiment provides an ultra-wideband compact circularly polarized helical antenna, including an antenna support 1, a double-arm helical line 2, a microstrip balun 3, a support plate 4 and an SMA high-frequency electrical connector 5;

[0034] See also Figure 1 As shown, the antenna bracket 1 is a conical cylinder with upper and lower openings, and the bottom diameter is large and the top diameter is small. Two spiral grooves extending from bottom to top are provided on the outer wall of the antenna bracket 1 for installing the double-arm spiral wire 2. As a preferred example of this embodiment, the material of the antenna bracket 1 is selected from glass fiber reinforced plastic;

[0035] The double-arm helical wire 2 includes a first helical wire and a second helical wire, which are respectively installed in two helical grooves on the outer wall of the antenna bracket 1. The bottom ends of the first helical wire and the second helical wire are fixedly connected to the antenna bracket 1 by metal screws.

[0036] See also Figures 3 to 6 As shown, the microstrip balun 3 includes a PCB board 31, a first coaxial feed line 32 and a second coaxial feed line 33. The PCB board 31 is inserted into the antenna bracket 1 along the axial direction of the antenna bracket 1. In this embodiment, two slide grooves are symmetrically opened on the inner wall of the antenna bracket 1. The edge of the PCB board 31 is inserted into the slide groove, and the PCB board 31 is installed in the antenna bracket 1. The first coaxial feed line 32 and the second coaxial feed line 33 are respectively arranged on the two side surfaces of the PCB board 31 along the axial direction of the antenna bracket 1. The top end of the first helix is ​​connected to the top end of the first coaxial feed line 32, and the top end of the second helix is ​​connected to the top end of the second coaxial feed line 33; as a preferred example of this embodiment, the top end of the first helix is ​​fixedly connected to the top end of the first coaxial feed line 32 by welding, and the top end of the second helix is ​​fixedly connected to the top end of the second coaxial feed line 33 by welding.

[0037] See also Figure 3As shown, the support plate 4 is fixedly mounted on the bottom end of the PCB board 31 and on one side of the PCB board 31. In this embodiment, the support plate 4 is fixedly mounted on one side of the PCB board 31 by four screws; as a preferred example of this embodiment, the material of the support plate 4 is polyimide.

[0038] The SMA high frequency electrical connector 5 is mounted on the support plate 4 and is used to transmit the guided wave to the microstrip balun 3 .

[0039] See also Figure 2 As shown in FIG. 1 , as a preferred example of this embodiment, the ultra-wideband compact circularly polarized helical antenna provided in this embodiment further includes a fixing sleeve 6, which is embedded in the top end of the antenna bracket 1. The fixing sleeve 6 is provided with a fixing groove along the axial direction, and the top end of the PCB board 31 is inserted into the fixing groove to fix the PCB board 31. Figure 4 and Figure 6 As shown, radial through holes are provided on both sides of the fixing sleeve 6, and the top ends of the first helix and the second helix pass through the through holes on the fixing sleeve 6 and are welded to the first coaxial feed line 32 and the second coaxial feed line 33. As a preferred example of this embodiment, the fixing sleeve 6 is made of polyimide.

[0040] The dimensions of an ultra-wideband compact circularly polarized helical antenna provided in this embodiment are within the following ranges according to different requirements: the total height of the antenna is 1000 mm, the diameter of the bottom end of the antenna is Ф270 mm, the diameter of the top end is Ф18 mm, the spiral pitch of the double-arm spiral line is 33 mm, which is about 0.3 to 1.8 times the antenna operating wavelength, the size of the microstrip balun is 85*255*2 mm, and the weight is 4 kg. It is suitable for use in ultra-wideband microwave radiometer systems for satellites and ground stations.

[0041] The electrical interface of the antenna includes a coaxial threaded radio frequency interface, and the mechanical installation interface of the antenna can be determined as needed. In this embodiment, there is no restriction on the electrical interface of the antenna.

[0042] The working principle of the ultra-wideband compact circularly polarized helical antenna provided in this embodiment is that the TEM guided wave is transmitted to the microstrip balun 3 through the SMA high-frequency electrical connector 5, and then transmitted to the double-arm helix 2 through the top after passing through the microstrip balun 3 to form a quasi-traveling wave, and then the circularly polarized wave is formed through the double-arm helix 2 and radiated into the free space to form a wide-beam circularly polarized electromagnetic wave. The ultra-wideband compact circularly polarized helical antenna provided in this embodiment solves the problem of the need to radiate circularly polarized electromagnetic waves within a wide frequency band by using a double-arm conical spiral plus an ultra-wideband microstrip balun. At the same time, it achieves the beneficial effects of small size, light weight, reliable and stable structure, etc.

[0043] This antenna is a passive structural component product. Through different height and diameter structures, it can meet different electrical performance requirements and achieve specific functions. Figures 7 to 9 As shown, the 3dB beam width of the ultra-wideband compact circularly polarized helical antenna provided in this embodiment is about ±80°, the maximum gain is greater than 9dB, the front-to-back ratio is better than 25dB, and the circular polarization axis ratio within the beam is less than 3dB, which better meets the needs of general satellites; the final center frequency of the ultra-wideband compact circularly polarized helical antenna assembly provided in this embodiment is 1.2GHz, the antenna has a standing wave of less than 2 within 0.3-5GHz, and the impedance bandwidth exceeds 16 times the frequency. In summary, the present invention can realize a broadband compact circularly polarized helical antenna, and the obtained integrated structure has good in-band standing waves.

[0044] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. An ultra-wideband compact circularly polarized helical antenna, characterized in that: It includes an antenna bracket, a double-arm spiral line, a microstrip balun, a support plate and an SMA high-frequency electrical connector; The antenna bracket is a conical cylinder with upper and lower openings, and the outer wall of the antenna bracket is provided with two spiral grooves extending from bottom to top; The double-arm helical wire comprises a first helical wire and a second helical wire, which are respectively installed in the two helical grooves, and the bottom ends of the first helical wire and the second helical wire are both fixedly connected to the antenna bracket; The microstrip balun includes a PCB board, a first coaxial feed line and a second coaxial feed line, the PCB board is inserted into the antenna bracket along the axial direction of the antenna bracket, the first coaxial feed line and the second coaxial feed line are respectively arranged on two side surfaces of the PCB board along the axial direction of the antenna bracket, the top end of the first helix is ​​connected to the top end of the first coaxial feed line, and the top end of the second helix is ​​connected to the top end of the second coaxial feed line; The support plate is fixedly mounted on the bottom end of the PCB board; The SMA high-frequency electrical connector is mounted on the support plate and is used to transmit the guided wave to the microstrip balun.

2. The ultra-wideband compact circularly polarized helical antenna according to claim 1, characterized in that: It also includes a fixing sleeve, which is embedded in the top end of the antenna bracket. The fixing sleeve is provided with a fixing groove along the axial direction. The top end of the PCB board is inserted into the fixing groove to fix the PCB.

3. The ultra-wideband compact circularly polarized helical antenna according to claim 1, characterized in that: Two slide grooves are symmetrically opened on the inner wall of the antenna bracket, and the edge of the PCB board is inserted into the slide groove, so that the PCB board is installed in the antenna bracket.

4. The ultra-wideband compact circularly polarized helical antenna according to claim 1, characterized in that: The top end of the first helical line is connected to the top end of the first coaxial feeder line by welding, and the top end of the second helical line is connected to the top end of the second coaxial feeder line by welding.

5. The ultra-wideband compact circularly polarized helical antenna according to claim 1, characterized in that: The bottom diameter of the antenna bracket is Φ270mm, the top diameter is Φ18mm, and the spiral pitch of the double-arm spiral line is 33mm.

6. The ultra-wideband compact circularly polarized helical antenna according to claim 2, characterized in that: The material of the fixing sleeve is polyimide.

7. The ultra-wideband compact circularly polarized helical antenna according to claim 1, characterized in that: The material of the support plate is polyimide.

8. The ultra-wideband compact circularly polarized helical antenna according to claim 1, characterized in that: The material of the antenna bracket is glass fiber reinforced plastic.

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