CN112467395B - A miniaturized low-profile dual circularly polarized antenna - Google Patents

Abstract

The present invention relates to a miniaturized low-profile dual circular polarization antenna, comprising a pair of orthogonal annular dipoles, a coupling feeder, a first supporting dielectric plate, a second supporting dielectric plate, a feeding coaxial line, a feeding network board and a reflecting plate. The dipole and the coupling feeder layer use TLY plates as dielectric substrates, and the dipole and the feeder are printed on both sides of the dielectric substrate; the dipole is printed on the bottom surface, and the coupling feeder is printed on the top surface; one section of the feeder is on the top surface of the dielectric, and one section is on the bottom surface of the dielectric substrate, connected by via-hole short-circuit metal columns; the dipole adopts two pairs of orthogonal square ring structures, and each pair of dipoles has four protruding branches added diagonally, and a section of uneven coupling is introduced between the dipole and the resonator, changing the current distribution on the dipole, thereby controlling the movement of the mode, introducing a new resonance point, and improving the bandwidth of the antenna. The present invention solves the design and installation problems of miniaturized broadband antennas in compact multimode terminals.

Description

A miniaturized low-profile dual circularly polarized antenna

Technical Field

The invention relates to a miniaturized low-profile dual circular polarization antenna, belonging to the technical field of satellite communications.

Background technique

Wide-band antennas can transmit or receive signals in multiple working frequency bands, effectively improving the aperture efficiency of the antenna and realizing the reuse of the same aperture of the antenna in a small space. They have been widely used in satellite communications, navigation, data transmission, etc.

In the field of satellite communications, with the development of antenna pan-satellite technology, satellite communication antennas are moving towards miniaturization, low profile, and broadband, requiring antennas to work in multiple frequency bands. At the same time, within a limited aperture, relatively stringent requirements are usually placed on the size and weight of the antenna. Dipole antennas have the advantages of wide working frequency band and good directional pattern stability. Miniaturization, low profile, and dual circular polarization can be achieved through reasonable structural design.

In the fields of communication, navigation and radar, many broadband circularly polarized antennas have appeared, such as microstrip antennas, array antennas and log-periodic antennas. However, the above antennas have relatively narrow bandwidth and high antenna height under the same size, and are not suitable for the miniaturized, low-profile and broadband transmission environment of satellite communications.

Summary of the invention

The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to propose a miniaturized low-profile dual circularly polarized antenna, and to solve the design and installation problems of miniaturized broadband antennas in compact multi-mode terminals.

The solution of the present invention is:

A miniaturized low-profile dual circular polarization antenna includes a pair of orthogonal annular dipoles, a coupling feed line, a first supporting dielectric plate, a second supporting dielectric plate, a feeding coaxial line, a feeding network plate and a reflecting plate.

The dipole and coupling feed layer use TLY board as the dielectric substrate, and the dipole and feed line are printed on both sides of the dielectric substrate; the dipole is printed on the bottom surface, and the coupling feed line is printed on the top surface; one section of the feed line is on the top surface of the dielectric, and the other section is on the bottom surface of the dielectric substrate, connected by via short-circuit metal columns;

The dipole adopts two pairs of orthogonal square ring structures, and each pair of dipoles has four protruding branches added diagonally, introducing a section of uneven coupling between the dipole and the resonator, changing the current distribution on the dipole, changing the current distribution on the dipole, thereby controlling the movement of the mode, introducing a new resonance point, and improving the bandwidth of the antenna;

Two layers of dielectric support structure are added between the dipole layer and the feeding network to reduce the height of the dipole antenna. The first layer of supporting dielectric plate uses hard foam with a dielectric constant of 1.1 and a thickness of 8 mm, and the second layer of supporting dielectric plate uses TP-2 dielectric plate with a dielectric constant of 6.15 and a thickness of 13 mm.

The feeding coaxial line adopts a three-section split SMP structure, the upper section adopts a label-type SMP connector (51), the outer conductor is connected to a ring arm of the dipole, and the inner conductor via hole is welded to the coupling feeder line on the top layer.

Furthermore, the signal is input through a 50Ω standard coaxial line and then converted to the feed line. The energy is coupled to the other arm of the circular dipole through the feed line to achieve feeding. The impedance matching is adjusted by changing the size of the "key" type coupling feed line.

Furthermore, the lower section adopts a stick-on SMP connector, the outer conductor is welded to the ground of the feed network, and the inner conductor is welded to the signal input terminal of the feed network.

Furthermore, the middle section adopts a standard SMP-KK adapter to achieve upper and lower plug-in fixation.

Furthermore, the feed network board adopts a slot coupling structure 3dB directional coupling bridge, stacking multiple layers of dielectric boards together, with the stacked common surface serving as a ground plate, a certain shape of slots being opened on the ground plate, and the upper and lower dielectric boards on both sides of the slot respectively having patch structures, and the upper and lower patches produce a slot coupling effect through the middle slot.

Furthermore, the first port of the slot coupling structure 3dB bridge as input is matched, while the fourth port is isolated, the second port is a through port, and the third port is a coupled port; the even-mode and odd-mode input impedances of the coupling bridge at the first port are expressed as:

Where Z _0e and Z _0o are the even-mode and odd-mode characteristic impedances, Z ₀ is the terminal load impedance, and C is the voltage coupling coefficient.

Furthermore, the dipole layer, the first supporting dielectric plate, the second supporting dielectric plate, the feeding network plate and the reflecting plate adopt an up-and-down stacking structure, so that the plug-in SMP connector is not subjected to stress.

Furthermore, four support columns are installed at the four corners of the antenna, and the dipole patch, the supporting medium board and the feeding network board are fixed on the reflector by screws embedded in the support columns.

Furthermore, the antenna has an operating bandwidth of 44%, covering a frequency band of 1.6 GHz to 2.5 GHz; the antenna array element size is 0.4λ×0.4λ×0.25λ, where λ is the wavelength of the center frequency.

Furthermore, within the working frequency band, the antenna standing wave is less than 2.0, the maximum gain of the array element is greater than 5.0dB, and the array gain is greater than 12.0dB.

The beneficial effects of the present invention compared with the prior art are:

(1) The present invention uses 6 sequentially rotating array elements to form a circular ring array, which has good symmetry and high aperture utilization. By using the principle of secondary circular polarization, the axial ratio bandwidth can be increased and the circular polarization characteristics of the antenna during wide-angle scanning can be improved;

(2) The array element of the present invention adopts a planar dipole structure, and the dipole adopts an asymmetric square ring structure. Each pair of dipoles has four protruding branches added diagonally, introducing uneven coupling feeding, which effectively increases the working bandwidth of the antenna. At the same time, the coupling feed line adopts a "key" type structure to further improve impedance matching and achieve broadband matching within the resonance bandwidth;

(3) The present invention adds two layers of supporting dielectric layers on the basis of the planar dipole, thereby reducing the height of the antenna. By selecting high and low dielectric constants and supporting plates of different thicknesses, the antenna is miniaturized and has a low profile (60 mm × 60 mm × 25 mm) while ensuring that the relative bandwidth of the antenna reaches more than 44%;

(4) The feeding network of the present invention adopts a tightly coupled stripline 90° bridge, and a split SMP plug-in structure is adopted between the feeding network and the coupling feed line. The modified structure is welded to the feeding network and the coupling feed line at the top and bottom and embedded in the support plate, thereby solving the problem of circular polarization feeding of the dipole antenna.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic diagram of the present invention;

Fig. 2 is a schematic diagram of a planar dipole;

Figure 3 is a schematic diagram of dipole feeding;

FIG4 is a schematic diagram of a stripline coupled bridge;

FIG5 is a schematic diagram of the structure of a coaxial feeder;

FIG. 6 is a top view of the structure of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the embodiments.

As shown in Figures 1 and 6, the antenna array of the present invention is a schematic diagram. The antenna adopts a sequentially rotated circularly polarized array form, and a circularly polarized wave with higher polarization purity can be synthesized through two multi-linear polarized waves or circularly polarized waves. The six antenna array elements rotate 60° sequentially around the center of the circular array. The secondary circular polarization formed by the rotation of the unit further improves the circular polarization axial ratio bandwidth and improves the low elevation angle circular polarization performance of the antenna.

FIG2 is a schematic diagram of the array element structure of the present invention, which includes a pair of orthogonal annular dipoles 11 , a pair of “key” type coupling feed lines 12 , a first supporting dielectric plate 21 , a second supporting dielectric plate 22 , a feeding coaxial line 5 , a feeding network plate 3 and a reflector 4 .

The dipole and coupling feed layer use TLY board as the dielectric substrate, and the dipole and feed line are printed on both sides of the dielectric substrate. The dipole patch 11 is printed on the bottom surface, and the coupling feed line 12 is printed on the top surface. In order to prevent the two pairs of orthogonal feed lines from crossing, one section of the feed line is on the top surface of the dielectric, and the other section is on the bottom surface of the dielectric substrate, and they are connected by via short-circuit metal columns.

The dipole patch 11 adopts two pairs of orthogonal square ring structures. The asymmetric square ring structure can reduce the size of the dipole, and each pair of dipoles has four protruding branches added diagonally. A dipole acts as a ring resonator, and the movement of the second mode can be controlled by controlling the coupling between the dipole and the resonator. The introduction of the edge protruding branches, on the one hand, introduces a section of uneven coupling between the dipole and the resonator, and on the other hand, changes the current distribution on the dipole, thereby controlling the movement of the mode. The surface also changes the current distribution on the dipole, thereby controlling the movement of the mode, introducing a new resonance point, and improving the bandwidth of the antenna.

The height of a dipole antenna is generally about 1/4 wavelength. In order to reduce the height of the antenna, two layers of dielectric support structures are added between the dipole layer and the feed network. The first layer of supporting dielectric plate 21 uses a hard foam with a dielectric constant of 1.1 and a thickness of 8 mm, and the second layer of supporting dielectric plate 22 uses a TP-2 dielectric plate with a dielectric constant of 6.15 and a thickness of 13 mm. Through two layers of supporting structures with different dielectric constants and thicknesses, the height of the antenna can be reduced while ensuring the bandwidth, achieving a lower profile.

The coaxial feeder adopts a three-section split SMP structure. The upper section adopts a label-type SMP connector 51, the outer conductor is connected to a ring arm of the dipole, and the inner conductor is welded to the coupling feeder on the top layer through a hole. The signal is input through a 50Ω standard coaxial line and then converted to the feeder. The energy is coupled to the other arm of the ring dipole through the feeder to achieve feeding. The impedance matching is adjusted by changing the size of the "key" type coupling feeder. The lower section adopts a label-type SMP connector 52, the outer conductor is welded to the feed network ground, and the inner conductor is welded to the signal input end of the feed network. The middle section adopts a standard SMP-KK adapter 53 to achieve upper and lower plug-in fixation.

The feed network board 3 adopts a slot coupling structure 3dB directional coupling bridge, which uses a multi-layer dielectric plate slot coupling technology. The multi-layer dielectric plates are stacked together, and the stacked common surface is used as a ground plate. A certain shape is dug out on the ground plate to make a slot. The upper and lower dielectric plates on both sides of the slot have patch structures respectively. Through the middle slot, the upper and lower patches can produce a slot coupling effect. This feed network has the advantages of strong coupling, compact structure, wideband amplitude and good phase consistency.

The schematic diagram of the slot coupling structure 3dB bridge is shown in Figure 2-4. The first port as the input is matched, while the fourth port is isolated, the second port is a through port, and the third port is a coupled port. The even-mode and odd-mode input impedances of the coupling bridge at the first port can be expressed as:

Where Z _0e and Z _0o are the even-mode and odd-mode characteristic impedances, Z ₀ is the terminal load impedance, and C is the voltage coupling coefficient. When the terminal characteristic impedance Z ₀ = 50Ω and the voltage coupling coefficient C = 3dB, the even-mode characteristic impedance Z _0e = 120.5Ω and the odd-mode characteristic impedance Z _0o = 20.7Ω required for the design can be derived from the above formula.

The above-mentioned dipole layer 1, first supporting dielectric plate 21, second supporting dielectric plate 22, feed network plate 3 and reflector 4 adopt a stacked structure. In order to prevent the plug-in SMP connector from being stressed, four support columns 51 are installed at the four corners of the antenna, and the dipole patch, supporting dielectric plate and feed network plate are fixed to the reflector by screws embedded in the support columns.

The antenna has an operating bandwidth of 44%, covering a frequency band of 1.6GHz to 2.5GHz. The array element size is 60mm×60mm×25mm (0.4λ×0.4λ×0.25λ, where λ is the wavelength of the center frequency), the array size is Φ220mm×25mm, and the weight is less than 1Kg. Within the operating frequency band, the antenna standing wave is less than 2.0, the maximum gain of the array element is greater than 5.0dB, and the array gain is greater than 12.0dB. Beam scanning can be achieved according to usage requirements.

Specifically, the antenna is composed of 6 sequentially rotating antenna units forming a circular array, and each antenna array element includes a pair of orthogonal circular dipoles 11, a pair of "key" type coupling feed lines 12, a first supporting dielectric plate 21, a second supporting dielectric plate 22, a feeding coaxial line 5, a feeding network plate 3 and a reflecting plate 4. The dipole 1, the supporting plate 2 and the feeding network layer 3 are stacked and fixed on the reflecting plate 4 by laminating screws 41.

The annular array is composed of 6 identical antenna elements, each of which rotates 60° around the center of the ring in sequence, and the antenna element spacing is 68 mm.

The planar dipole adopts a stacked structure, which includes a dipole and a feed line 1, a first supporting dielectric plate 21, a second supporting dielectric plate 22, a feed network 4 and a reflector 5 from top to bottom.

The dipole and feeder are printed on both sides of the dielectric substrate. The dipole patch 11 is printed on the bottom surface, and the coupling feeder 12 is printed on the top surface. The dipole patch is in the form of an asymmetric square ring, and each pair of dipoles has four protruding branches at opposite corners.

The coupling feeder 12 adopts a "key" type asymmetric square ring structure, one section of the feeder is on the top surface of the dielectric, and the other section is on the bottom surface of the dielectric substrate, and they are connected through via short-circuit metal columns.

The support plate adopts two layers of dielectric plates with different dielectric constants. The dielectric constant of the first support plate 21 is 1.1, the dielectric constant of the second support plate 22 is 6.15, and the thickness of the first support plate is 8 mm.

As shown in FIG. 5 , the feeding coaxial line 5 described in the present invention is a split structure, and the upper and lower ends use label-type SMP connectors 51 and 52, which are respectively welded to the coupling feed line and the input end of the feeding network, and a standard SMP-KK adapter 53 is used in the middle to weld the feeding network and the coupling feed line together to feed a pair of orthogonal dipoles respectively.

The six antenna units form a circular sequentially rotating planar array. The antenna elements rotate 60° around the center of the ring with a spacing of 68 mm.

The planar dipole array element adopts a stacked structure, which includes, from top to bottom, a dipole and feed lines 11 and 12 , a first supporting dielectric plate 21 , a second supporting dielectric plate 22 , a feed network 3 and a reflector 4 .

The dipole patch 11 and the feeder 12 are printed on both sides of the dielectric substrate, the dipole is printed on the bottom surface, and the coupling feeder is printed on the top surface.

The coupling feeder 12 adopts a "key" type asymmetric square ring structure, one section of the feeder is on the top surface of the dielectric, and the other section is on the bottom surface of the dielectric substrate, and they are connected through via short-circuit metal columns.

The dipole patch 11 is in the form of an asymmetric square ring, and each pair of dipoles has four protruding branches at opposite diagonals.

The outer conductor of the feeding coaxial line 5 is connected to a ring arm of the dipole, and the inner conductor via hole is welded to the coupling feeding line 12 on the top layer.

The feeding coaxial line 5 is a split structure, with label-type SMP connectors 51 and 52 at the upper and lower ends, which are respectively welded to the coupling feeder line 12 and the input end of the feeding network, and a standard SMP-KK53 plug-in is used in the middle.

The support plate is made of two layers of dielectric plates with different dielectric constants. The dielectric constant of the first support plate 21 is smaller by 1-3, and the dielectric constant of the second support plate 22 is larger by 5-10. The thickness of the first support plate is smaller than that of the second support plate.

The present invention adopts 6 sequentially rotating array elements to form a circular ring array, and the circular ring array has good symmetry and high aperture utilization. By using the principle of secondary circular polarization, the axial ratio bandwidth can be increased and the circular polarization characteristics of the antenna during wide-angle scanning can be improved;

The array element of the present invention adopts a planar dipole structure, and the dipole adopts an asymmetric square ring structure. Each pair of dipoles has four protruding branches added diagonally, introducing uneven coupling feeding, which effectively increases the working bandwidth of the antenna. At the same time, the coupling feed line adopts a "key" type structure to further improve impedance matching and achieve broadband matching within the resonance bandwidth;

The present invention adds two layers of supporting dielectric layers on the basis of the planar dipole, reduces the height of the antenna, and realizes the miniaturization and low profile (60mm×60mm×25mm) of the antenna while ensuring that the relative bandwidth of the antenna reaches more than 44% by selecting high and low dielectric constants and supporting plates of different thicknesses;

The feeding network of the present invention adopts a tightly coupled stripline 90° bridge, and a split SMP plug-in structure is adopted between the feeding network and the coupling feed line. The modified structure is welded to the feeding network and the coupling feed line at the top and bottom and embedded in the support plate, thereby solving the problem of circular polarization feeding of the dipole antenna.

Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims (6)

1. A miniaturized low-profile dual circular polarization antenna, characterized in that it comprises a pair of orthogonal annular dipoles (11), a pair of orthogonal "key" type annular coupling feed lines (12), a first supporting dielectric plate (21), a second supporting dielectric plate (22), a feeding coaxial line (5), a feeding network plate (3) and a reflecting plate (4), The dipole and the "key" type coupling feeder constitute a dipole layer. The dipole and the "key" type coupling feeder are printed on two surfaces of a dielectric substrate, which is a TLY board. The dipole (11) is printed on the top surface of the dielectric substrate, and the "key" type coupling feeder is printed on the bottom surface of the dielectric substrate. The "key" type coupling feeder is connected by two parts, one of which is a ring-shaped coupling section and the other is a long strip-shaped feeding section. A part of the feeding section of one of the "key" type coupling feeders is arranged on the top surface of the dielectric substrate, and the part is connected to the other part of the feeding section through a short-circuit metal column to prevent the two orthogonal "key" type coupling feeders from crossing. Each pair of dipoles includes two symmetrical square ring structures. A protruding branch is set on the diagonal of each square ring structure to change the current distribution on the dipole, thereby controlling the movement of the mode, introducing a new resonance point, and improving the bandwidth of the antenna. A two-layer dielectric support structure is arranged between the dipole layer and the feed network board to reduce the height of the dipole antenna, the first supporting dielectric plate (21) adopts a hard foam with a dielectric constant of 1.1 and a thickness of 8 mm, and the second supporting dielectric plate (22) adopts a TP-2 dielectric plate with a dielectric constant of 6.15 and a thickness of 13 mm; The feeding coaxial line (5) adopts a three-section split SMP structure, the upper section adopts a label-type SMP connector (51), the outer conductor is connected to a square ring structure of a dipole, and the inner conductor is connected to a "key" type coupling feeder line; The signal is input through a 50Ω standard coaxial line and then converted to a "key" type coupled feed line, which is then coupled to another square ring structure of the ring dipole to achieve feeding. The impedance matching can be adjusted by changing the size of the "key" type coupled feed line. The feed network board (3) adopts a slot coupling structure 3dB directional coupling bridge, stacking multiple dielectric boards together, with the stacked common surface serving as a grounding plate, a slot of a specific shape being opened on the grounding plate, and the upper and lower dielectric boards located on both sides of the slot respectively having patch structures, and the upper and lower patches produce a slot coupling effect through the middle slot; The first port of the slot-coupled 3dB bridge is the input port, the fourth port is the isolation port, the second port is the through port, and the third port is the coupling port; the even-mode and odd-mode input impedances of the coupling bridge at the first port are expressed as: Where Z _0e and Z _0o are the even-mode and odd-mode characteristic impedances, Z ₀ is the terminal load impedance, and C is the voltage coupling coefficient; The antenna working bandwidth is 44%, covering the frequency band of 1.6GHz to 2.5GHz; the antenna array element size is 0.4λ×0.4λ×0.25λ, where λ is the wavelength of the center frequency. 2. A miniaturized low-profile dual circular polarization antenna according to claim 1, characterized in that the lower section of the feeding coaxial line adopts a stick-on SMP connector, the outer conductor is welded to the ground of the feeding network board, and the inner conductor is welded to the signal input end of the feeding network board. 3. A miniaturized low-profile dual circular polarization antenna according to claim 1, characterized in that the middle section adopts a standard SMP-KK adapter (53) to achieve upper and lower plug-in fixation. 4. A miniaturized low-profile dual circular polarization antenna according to claim 1, characterized in that the dipole layer, the first supporting dielectric plate (21), the second supporting dielectric plate (22), the feed network plate (3) and the reflector (4) adopt an upper and lower stacking structure so that the plug-in SMP connector is not subjected to force. 5. A miniaturized low-profile dual circular polarization antenna according to claim 1, characterized in that four support columns (51) are installed at the four corners of the antenna, and the dipole layer, two supporting dielectric plates and the feed network board are fixed on the reflector through the support columns. 6. A miniaturized low-profile dual circularly polarized antenna according to claim 1, characterized in that, within the operating frequency band, the antenna standing wave is less than 2.0, the maximum gain of the array element is greater than 5.0 dB, and the array gain is greater than 12.0 dB.