A circularly polarized reflection path decoupling antenna

Abstract

The present invention discloses a circularly polarized reflection path decoupling antenna. A pair of horizontal metal strips and a pair of vertical metal strips are placed at the center above a pair of circularly polarized patch antenna units. The two pairs of metal strips are used to adjust the reflection phase of near-field space waves, and the vertical metal strips are used to restore and improve the axial ratio, so as to realize the circularly polarized reflection path decoupling antenna. While realizing decoupling, the axial ratio bandwidth is widened to obtain additional performance benefits, and the structure and design complexity are low and the design freedom is high.

Description

Technical Field

[0001] The invention relates to a microwave communication device, in particular to a circular polarization reflection path decoupling antenna. Background Art

[0002] Circularly polarized patch antennas can receive linearly polarized waves in any polarization direction, and the transmitted circularly polarized waves can be received by linearly polarized antennas in any direction. Therefore, they have the advantages of suppressing polarization mismatch and multipath interference, and have been widely used in global positioning systems, satellite communications, navigation systems, and radio frequency identification. When multiple circularly polarized patch antennas form a multi-unit circularly polarized antenna array, signal coupling will occur between antenna units through three main paths, namely, the ground current of the metal ground, the surface wave of the dielectric interface, and the near-field space wave. When the coupled signal is strong, it will cause problems such as active matching deterioration, bandwidth attenuation, and radiation pattern distortion. Therefore, it is necessary to interfere with or block the coupling path to achieve decoupling of the circularly polarized antenna. Furthermore, if there is a gain in performance relative to the antenna unit after decoupling, rather than just restoring matching, bandwidth, and radiation pattern distortion, this type of circularly polarized decoupled antenna will have a better competitive advantage.

[0003] There are two main design methods for circularly polarized decoupling patch antennas. The first is a path blocking decoupling method, which is mainly implemented by placing a vertically distributed periodic metamaterial structure on the coupling path between units to construct a transmission barrier on the coupling path between units, thereby blocking one or more coupling signals between units to reduce mutual coupling. This method easily complicates the antenna structure, is not conducive to integration and cost reduction, and after decoupling, although it has made some achievements in restoring matching, bandwidth, and pattern distortion compared to unit antennas, it does not obtain additional performance benefits. The second is a path cancellation decoupling method, which is mainly implemented by adding a "W"-shaped partially short-circuited metal strip, multiple quarter-wavelength short-circuited resonators, or introducing a new direct-type coupling channel through the patch antenna's own structure to achieve decoupling by canceling the original channel. This method can achieve circular polarization decoupling, but it also cannot obtain additional performance benefits, and there is a problem of low design freedom due to the mutual constraints between the decoupling and axial ratio of the antenna. Summary of the invention

[0004] Purpose of the invention: In view of the above-mentioned prior art, a circularly polarized reflection path decoupling antenna is proposed, which can achieve decoupling while widening the axial ratio bandwidth to obtain additional performance benefits, and ensure low structural and design complexity and high design freedom.

[0005] Technical solution: A circularly polarized reflection path decoupling antenna, comprising: placing a pair of horizontal metal strips and a pair of vertical metal strips at the center above a pair of circularly polarized patch antenna units, using the two pairs of metal strips to adjust the near-field spatial wave reflection phase, and the vertical metal strips to restore and improve the axial ratio, thereby achieving decoupling while improving the axial ratio bandwidth.

[0006] Furthermore, the two horizontal metal strips are symmetrical up and down and left and right, and are located at the center directly above the two metal patches of the pair of circularly polarized patch antenna units. The length of the horizontal metal strip is between 0.27λ0-0.28λ0, and the center distance is between 0.28λ0-0.3λ0. λ0 is the free space wavelength corresponding to the center frequency. When working, the two work simultaneously, and the current is distributed in a symmetrical half-wave, which is used to adjust the near-field spatial wave reflection phase, and then adjust the mutual coupling between the circularly polarized patch units.

[0007] Furthermore, the two vertical metal strips are symmetrical up and down and left and right, and are also placed at the center directly above the two metal patches and located on the inner side of the two horizontal metal strips. The length of the vertical metal strips is between 0.2λ0-0.21λ0, and the center distance is between 0.15λ0-0.17λ0. When working, the vertical metal strips on the excitation unit side take effect, and the current is distributed in a symmetrical half-wave, which is used to assist in adjusting the mutual coupling between the circularly polarized patch units and improving the axial ratio bandwidth of the circularly polarized antenna excitation unit.

[0008] Furthermore, the circularly polarized reflection path decoupling antenna includes a top metal structure, an upper dielectric substrate, a middle metal structure, a middle dielectric substrate, an intermediate metal ground, a bottom dielectric substrate and a bottom metal structure; the top metal structure is composed of two horizontal metal strips and two vertical metal strips; the middle metal structure is composed of two metal patches; two pairs of orthogonal cross grooves are etched on the middle metal ground, and the cross grooves are respectively opposite to the two metal patches; the bottom metal structure is two metal strips located directly below the center points of the cross grooves; the metal patches, the middle dielectric substrate and the intermediate metal ground constitute a circularly polarized patch antenna unit; the metal strips, the lower dielectric substrate and the intermediate metal ground constitute a microstrip feeder.

[0009] Furthermore, the center distance between the two metal patches is 0.5λ0.

[0010] Beneficial effects: The existing circularly polarized decoupling patch antenna can only realize the basic decoupling function, cannot generate additional performance gain, and has one or both of the problems of complex structure or low design freedom. The present invention places a pair of horizontal metal strips and a pair of vertical metal strips at the center above a pair of circularly polarized patch antenna units, and utilizes the two pairs of metal strips to adjust the near-field spatial wave reflection phase, and the vertical metal strips to restore and improve the axial ratio, so as to realize the circularly polarized reflection path decoupling antenna. While realizing decoupling, the axial ratio bandwidth is widened to obtain additional performance benefits, and the structure and design complexity are low and the design freedom is high.

[0011] Specifically, the two horizontal metal strips are symmetrical up and down and left and right, and are located at the center directly above the two metal patches. The length is between 0.27λ0-0.28λ0, and the distance is between 0.28λ0-0.3λ0. When working, the two strips act simultaneously, and the current is distributed in a symmetrical half-wave, which is mainly used to adjust the near-field spatial wave reflection phase, and then adjust the mutual coupling between the circularly polarized patch units.

[0012] The two vertical metal strips are symmetrical up and down and left and right, and are also placed at the center directly above the two metal patches and on the inner side of the two horizontal metal strips. The length is between 0.2λ0-0.21λ0 and the distance is between 0.15λ0-0.17λ0. When working, the vertical metal strips on the excitation unit side take effect, and the current is distributed in a symmetrical half-wave, which is used to assist in adjusting the mutual coupling between the circularly polarized patch units and can improve the axial ratio bandwidth of the circularly polarized antenna excitation unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic cross-sectional structure diagram of a 1×2 circularly polarized decoupling patch antenna of the present invention;

[0014] Figure 2 3D layered diagram of the 1×2 circular polarization decoupling patch antenna of the present invention;

[0015] Figure 3 It is a simplified diagram of the current average amplitude distribution of the 1×2 circular polarization decoupling patch antenna of the present invention before and after decoupling at the center frequency, wherein Figure (a) corresponds to after decoupling, and Figure (b) corresponds to before decoupling;

[0016] Figure 4 The S parameter simulation results of the 1×2 circular polarization decoupling patch antenna of the present invention before and after decoupling are compared; wherein Figure (a) corresponds to the S parameter simulation results before decoupling, and Figure (b) corresponds to the S parameter simulation results after decoupling;

[0017] Figure 5The figure shows the comparison of the axial ratio simulation results of the circularly polarized antenna unit, the 1×2 undecoupled case and the decoupled case of the present invention; wherein figure (a) corresponds to the axial ratio simulation result of the unit, figure (b) corresponds to the axial ratio simulation result of the 1×2 case before decoupling, and figure (c) corresponds to the axial ratio simulation result of the 1×2 case after decoupling;

[0018] Figure 6 The present invention compares the simulation results of the radiation patterns before and after decoupling when the 1×2 circularly polarized decoupling patch antenna unit is excited; wherein Figure (a) is the simulation pattern of the phi=0° surface before decoupling, Figure (b) corresponds to the simulation pattern of the phi=90° surface before decoupling, Figure (c) corresponds to the simulation pattern of the phi=0° surface after decoupling, and Figure (d) corresponds to the simulation pattern of the phi=90° surface after decoupling. DETAILED DESCRIPTION

[0019] The present invention will be further explained below in conjunction with the accompanying drawings.

[0020] The circularly polarized reflection path decoupling antenna of the present invention has a 1×2 antenna structure schematic diagram as shown in FIG. Figure 1 , Figure 2 As shown, it is composed of a top metal structure 1, an upper dielectric substrate 2, a middle metal structure 3, a middle dielectric substrate 4, a middle metal ground 5, a bottom dielectric substrate 6 and a bottom metal structure 7.

[0021] The top metal structure 1 includes two horizontal metal strips 101 and two vertical metal strips 102, and the two vertical metal strips 102 are located inside the two horizontal metal strips 101; the widths of the metal strips are the same, the length of the horizontal metal strip 101 is greater than that of the vertical metal strip 102, the length of the horizontal metal strip 101 is between 0.27λ0-0.28λ0, the center distance is between 0.28λ0-0.3λ0, the length of the vertical metal strip 102 is between 0.2λ0-0.21λ0, and the center distance between the two vertical metal strips 102 is between 0.15λ0-0.17λ0, where λ0 is the free space wavelength corresponding to the center frequency. The middle layer metal structure 3 includes two metal patches 301, whose center spacing is 0.5λ0. Two pairs of orthogonal cross grooves 501, 502 are etched on the middle layer metal ground 5, and the cross grooves 501, 502 are respectively opposite to the two metal patches 301. The bottom metal structure 7 is two metal strips 701, 702 located directly below the center points of the cross slots 501, 502. The horizontal metal strip 101 and the vertical metal strip 102 form a decoupling structure. The metal patch 301, the middle dielectric substrate 4 and the middle metal ground 5 form a circularly polarized patch antenna unit. The metal strips 701, 702, the lower dielectric substrate 6 and the middle metal ground 5 form a microstrip feeder.

[0022] For the proposed circularly polarized reflection path decoupling antenna, the signal is fed from the patch antenna unit 1, most of the signal forms circularly polarized radiation through the patch antenna unit and the decoupling structure, and part of the signal is reflected by the decoupling structure above and cancels the original coupled signal to form decoupling. When the signal is fed from the patch antenna unit 2, the process is similar to the above, and the signal flows in the opposite direction.

[0023] In this process, when unit 1 is excited, the current distribution of the two horizontal metal strips in the decoupling structure is stronger, and the current distribution of the vertical metal strip on the left is stronger than that of the vertical metal strip on the right, as shown in Figure 3 As shown in (a), the current of the horizontal metal strip and the current of the vertical metal strip on the left are both half-wave symmetrically distributed. At this time, after the coupling signal based on the near-field space wave encounters the decoupling structure, the phase of this coupling path is adjusted under the reflection of the two horizontal half-wave oscillators and the half-wave oscillator on the left, and the phase varies with the length of the half-wave oscillator. Therefore, by adjusting the length of the half-wave oscillator, it can form an anti-phase cancellation with the original coupling path, thereby realizing the weak current distribution on the coupling unit and achieving decoupling. In this decoupling process, the horizontal metal strip plays a major role, and the vertical metal strip on the left plays an auxiliary role. However, after introducing the vertical metal strip on the left, the deterioration of the antenna axial ratio caused by the introduction of the horizontal metal strip can be repaired and improved, so that the axial ratio bandwidth of the decoupled antenna is better than that of the antenna before decoupling or even a single antenna unit. On the contrary, when unit 2 is excited, the two horizontal metal strips are decoupled from the vertical metal strip on the right, and the vertical metal strip on the right enables the decoupled antenna to obtain a wider axial ratio bandwidth.

[0024] Compared with the existing circularly polarized decoupling patch antenna, the advantages of the present invention are that while achieving decoupling, the axial ratio bandwidth can be widened relative to the antenna unit, and the structure and design complexity are low and the design freedom is high.

[0025] This embodiment uses RO4003C dielectric substrate, and the overall antenna unit size is 0.95λ0×0.7λ0×0.03λ0. The antenna structure diagram is as follows: Figure 1 , Figure 2 shown. Figure 4 The S parameter simulation results of the 1×2 embodiment of the present invention before and after decoupling are shown. Figure 4It can be seen that the -10dB impedance matching band of the 1×2 circularly polarized patch antenna before decoupling is from 3.45GHz to 3.58GHz, with a relative bandwidth of 3.7%, and the -10dB impedance matching band of the 1×2 circularly polarized patch antenna after decoupling is from 3.41GHz to 3.57GHz, with a relative bandwidth of 4.6%, indicating that the decoupling structure can suppress the deterioration of the matching bandwidth. In addition, the mutual coupling level of the 1×2 circularly polarized patch antenna within the 3dB axial ratio range is -17dB before decoupling, and the mutual coupling level of the antenna within the 3dB axial ratio range is -47dB after decoupling, which shows that the mutual coupling between units has been effectively suppressed. Figure 5 The simulation results of the axial ratios of the circularly polarized antenna unit, the 1×2 undecoupled case and the decoupled case of the present invention are compared. The 3dB axial ratio frequency band of the circularly polarized antenna unit ranges from 3.48 GHz to 3.51 GHz, and the relative bandwidth is 0.9%. Before decoupling, the 3dB axial ratio frequency band of the 1×2 circularly polarized patch antenna ranges from 3.50 GHz to 3.52 GHz, and the relative bandwidth is 0.6%. After decoupling, the 3dB axial ratio frequency band of the 1×2 circularly polarized patch antenna ranges from 3.48 GHz to 3.53 GHz, and the relative bandwidth is 1.4%. It can be seen that after decoupling, the circular polarization effect is not only restored, but also the bandwidth is further widened.

[0026] Figure 6 The comparison of the simulation results of the radiation pattern before and after decoupling when the single unit of the 1×2 circularly polarized antenna of the present invention is excited is shown. Figure 5 From (a) and (b), we can see that the average cross-polarization levels of unit 1 before decoupling in the phi = 0° plane and phi = 90° plane are 14.9 dB and 15.1 dB respectively; Figure 5 From (c) and (d), we can see that after decoupling, the average cross-polarization levels of unit 1 in the phi=0° plane and phi=90° plane are 18.5dB and 23.7dB respectively. It can be seen that the decoupling measure can suppress the deterioration of the cross-polarization level to a certain extent.

[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A circularly polarized reflection path decoupling antenna, characterized in that: include: A pair of horizontal metal strips and a pair of vertical metal strips are placed at the center above a pair of circularly polarized patch antenna units. The two pairs of metal strips are used to adjust the near-field spatial wave reflection phase, and the vertical metal strips are used to restore and improve the axial ratio, thereby achieving decoupling and improving the axial ratio bandwidth. The two horizontal metal strips are symmetrical up and down and left and right, and are located at the center just above the two metal patches of the pair of circularly polarized patch antenna units. The length of the horizontal metal strip is between 0.27λ0-0.28λ0, and the center distance is between 0.28λ0-0.3λ0, where λ0 is the free space wavelength corresponding to the center frequency. When working, the two strips act simultaneously, and the current is symmetrically distributed in half waves, which is used to adjust the near-field space wave reflection phase, thereby adjusting the mutual coupling between the circularly polarized patch units. The two vertical metal strips are symmetrical up and down and left and right, and are also placed at the center directly above the two metal patches and on the inner side of the two horizontal metal strips. The length of the vertical metal strips is between 0.2λ0-0.21λ0, and the center distance is between 0.15λ0-0.17λ0. When working, the vertical metal strips on the excitation unit side take effect, and the current is distributed in a symmetrical half-wave, which is used to assist in adjusting the mutual coupling between the circularly polarized patch units and improve the axial ratio bandwidth of the circularly polarized antenna excitation unit.

2. The circularly polarized reflection path decoupling antenna according to claim 1, characterized in that: The circularly polarized reflection path decoupling antenna comprises a top metal structure (1), an upper dielectric substrate (2), an intermediate metal structure (3), an intermediate dielectric substrate (4), an intermediate metal ground (5), a bottom dielectric substrate (6) and a bottom metal structure (7); the top metal structure (1) is composed of two horizontal metal strips and two vertical metal strips; the intermediate metal structure (3) is composed of two metal patches; two pairs of orthogonal cross grooves are etched on the intermediate metal ground (5), and the cross grooves are respectively opposite to the two metal patches; the bottom metal structure (7) is two metal strips located directly below the center points of the cross grooves; the metal patches, the intermediate dielectric substrate (4) and the intermediate metal ground (5) constitute a circularly polarized patch antenna unit; the metal strips, the bottom dielectric substrate (6) and the intermediate metal ground (5) constitute a microstrip feeder.

3. The circularly polarized reflection path decoupling antenna according to claim 2, characterized in that: The center distance between the two metal patches is 0.5λ0.

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