A dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna and its processing method

Abstract

The present invention discloses a 2×2 dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity multi-input multi-output antenna and a processing method, belonging to the field of antenna technology. It is composed of four identical Fabry cavity antenna units arranged in a 90° rotation. The antenna unit consists of a feed antenna and a partial reflector. The feed antenna is a hybrid structure of a slot and a patch. The chiral metamaterial is used as a partial reflector unit to realize left-handed circularly polarized waves and right-handed circularly polarized waves. The broadband metamaterial absorber is introduced to improve the port isolation between adjacent antenna units. The antenna array has high isolation, high gain, dual-band, and dual circular polarization characteristics, and is suitable for modern mobile communication applications. The processing method comprises the following steps: pre-processing the feed antenna; processing the partial reflector; processing the absorber; placing a partial reflector above the feed antenna to form an antenna unit; rotating and arranging the antenna units into a MIMO antenna array; placing an absorber between each unit.

Description

Technical Field

[0001] The invention relates to the technical field of antenna engineering, and in particular to a dual-band, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna. Background Art

[0002] Multiple-input multiple-output antennas, also known as MIMO antennas, have attracted extensive attention in the antenna field because they have the ability to greatly increase data rates and channel capacity without occupying additional bandwidth compared to traditional single antennas. MIMO antennas have potential applications in current and next-generation wireless communication systems, sensor systems, radars, and satellite communications.

[0003] MIMO antennas are widely used in wireless communications and other fields due to their advantages of increasing spatial freedom, improving system performance, and increasing channel capacity. Circularly polarized antennas have attracted widespread attention due to their strong ability to resist multipath fading, so circularly polarized MIMO antennas have been widely developed. In recent years, a large number of studies have been conducted on dual-frequency circularly polarized MIMO antennas. The methods for achieving dual-frequency circular polarization can be roughly divided into three categories. (1) Patch antenna method: circular polarization is achieved by opening orthogonal slots, circular slots, cutting angles, etc. in the patch antenna to change the distribution of current on the patch. However, this type of antenna usually has a narrow axial ratio bandwidth and low gain, which is caused by the radiation mechanism of the patch antenna itself. (2) Phase delay method: This method is to divide the signal into two signals with equal amplitude and 90 degrees phase difference through a 90-degree power divider, and stimulate the two orthogonal polarization input ends of a dual-frequency dual-linear polarization antenna to form circularly polarized radiation. Although this method can achieve a wide axial ratio bandwidth, it introduces an additional feeding structure, which makes the entire MIMO antenna feeding system complicated. (3) Polarization conversion method: A polarization conversion cover is loaded above the linear polarization antenna to realize the conversion of linear polarization waves to circular polarization waves. It is planned that the conversion cover can also act as a partial reflection surface to achieve gain improvement.

[0004] In summary, traditional circularly polarized MIMO antennas have problems such as narrow axial ratio bandwidth and low gain, while future wireless communication systems will require wider axial ratio bandwidth, higher gain and lower latency. Therefore, it is very practical to study dual-frequency, dual circularly polarized, high-isolation MIMO antennas. Summary of the invention

[0005] Currently, the publicly available circularly polarized MIMO antennas either have insufficient gain and axial ratio bandwidth, which limits their scope of application, or have insufficient isolation, which deteriorates system performance and lacks practicality.

[0006] The technical problem to be solved by the present invention is: by loading a partial reflecting surface, the purpose is to improve the gain of the feeding antenna and realize the dual-frequency polarization conversion, and then form a MIMO antenna in an array manner, and by loading an absorber, the isolation between each unit is improved. For the first time, a MIMO antenna with different circular polarization forms working in two frequency bands is proposed, and high isolation is achieved.

[0007] The present invention is achieved through the following technical solutions:

[0008] A dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna includes a feed antenna, a partial reflective surface, and an absorber. The partial reflective surface covers the top of the feed antenna to improve the gain of the feed antenna and realize polarization conversion. The feed antenna and the partial reflective surface form an antenna unit. The antenna units are arranged in a 90° rotation to form a MIMO antenna. The absorber is loaded between the antenna units to improve the isolation of the MIMO antenna.

[0009] Compared with the existing circularly polarized MIMO antenna, the dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna proposed in the present invention has the following innovations:

[0010] A high-gain dual-frequency circularly polarized Fabry cavity antenna is obtained by covering a partial reflection surface above a feeding antenna. The partial reflection surface has a high reflection coefficient and a dual-frequency polarization conversion function. Unlike a general dual-frequency circularly polarized antenna, the present invention only needs one feeding port to excite a dual-frequency linearly polarized antenna. When the linearly polarized wave reaches the partial reflection surface, a part of the electromagnetic wave is reflected back to the floor. The electromagnetic wave reflected back to the ground reaches the partial reflection surface again after being reflected by the ground. Therefore, the electromagnetic wave is reflected multiple times in the cavity to achieve in-phase superposition of the electric field, and finally transmits out of the partial reflection surface, thereby enhancing the gain of the feeding antenna. The transmitted electromagnetic wave is radiated in the form of circular polarization to achieve polarization conversion.

[0011] The advantage of using a patch-type feeding antenna is that the patch antenna has structural characteristics such as compact structure, easy processing, easy design, and low cost, so that the overall structure of the Fabry resonant cavity antenna is simple and easy to implement.

[0012] As a further description of the present invention, a second dielectric plate is introduced into the feeding antenna, and the microstrip feeding on the lower surface of the first dielectric is coupled to the slotted ground on the upper surface and the patch on the lower surface of the second dielectric plate, resulting in a single-feed dual-frequency linearly polarized antenna that does not affect the overall profile of the Fabry cavity antenna.

[0013] As a further description of the present invention, the partial reflective surface covering the patch antenna includes a single-layer dielectric base with a double-layer printed metal structure.

[0014] As a further description of the present invention, the above-mentioned absorber loaded between the antenna units includes: the bottom layer of the fifth dielectric plate is a circular ring structure, 4 openings are spaced 90° apart on the ring, and the 4 openings are connected with 4 150Ω patch resistors; the bottom layer of the fourth dielectric plate is a circular ring structure, the ring is smaller than the top layer of the fifth dielectric plate, 4 openings are spaced 90° apart on the ring, and the 4 openings are connected with 4 150Ω patch resistors, wherein the position of the opening is rotated 45° relative to the position of the opening on the upper layer of the fifth dielectric plate, and 4 through holes are punched in the fourth dielectric plate, and the position of the through holes is the first The positions of the four dielectric plate resistors; the bottom layer of the sixth dielectric plate is fully copper-clad, and the top layer is a circular ring structure, with four openings spaced 90° apart on the ring, and the four openings are connected with four 150Ω chip resistors; the top layer of the seventh dielectric plate is a circular ring structure, which is smaller than the top layer of the sixth dielectric plate, with four openings spaced 90° apart on the ring, and the four openings are connected with four 150Ω chip resistors, wherein the position of the opening is rotated 45° relative to the position of the opening on the upper layer of the sixth dielectric plate, and four through holes are punched in the seventh dielectric plate, and the position of the through holes is the position where the fourth dielectric plate resistor is placed. The size and opening position of the circular ring of the fourth dielectric plate and the seventh dielectric plate are consistent; the size and opening position of the circular ring of the fifth dielectric plate and the sixth dielectric plate are consistent. There is no gap between the fourth dielectric plate, the fifth dielectric plate, the sixth dielectric plate and the seventh dielectric plate.

[0015] As a further description of the present invention, the specific structure of the feeding antenna of the dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna is as follows: the feeding line structure on the lower surface of the first dielectric plate is a single microstrip line fed by SMA, and the end of the microstrip line is bifurcated into two microstrip lines; a rectangular gap is opened in the center of the copper-clad structure on the upper surface; and a rectangular is clad at the center of the lower surface of the second dielectric plate. The copper-feeding first dielectric plate and the second dielectric plate are stacked in sequence in the order of the bottom layer being the first dielectric plate and the top layer being the second dielectric plate; wherein the thickness of the first dielectric plate and the second dielectric plate are the same; and the dielectric constant of the first dielectric plate and the second dielectric plate are the same.

[0016] As a further description of the present invention, the slit structure on the upper surface of the first dielectric substrate and the copper-clad structure on the lower surface of the second dielectric substrate are co-centrically arranged.

[0017] As a further description of the present invention, the first dielectric substrate is provided with a plurality of fixing holes, and the second dielectric plate is provided with a plurality of fixing holes corresponding to the fixing holes of the first dielectric plate. By fixing one end of the nylon dielectric support column in the fixing hole of the first dielectric plate and the other end in the fixing hole of the second dielectric plate, the second dielectric plate is supported and placed above the ground plane.

[0018] As a further description of the present invention, the specific structure of the absorber of the dual-frequency dual circularly polarized Fabry-Perot cavity MIMO antenna is as follows: the fourth dielectric plate, the fifth dielectric plate, the sixth dielectric plate and the seventh dielectric plate are stacked in the order of the bottom layer being the fourth dielectric plate, the next being the fifth dielectric plate, the sixth dielectric plate, and the top layer being the seventh dielectric plate. Then, they are periodically arranged into a cross shape, and the length and width of the cross shape are the sum of the thickness of the two ground planes and the four dielectric plates, the fifth dielectric plate, the sixth dielectric plate and the seventh dielectric plate. Among them, the thickness of the four dielectric plates, the fifth dielectric plate, the sixth dielectric plate and the seventh dielectric plate are the same, and the dielectric constant is the same.

[0019] As a further description of the present invention, the overall specific structure of the dual-frequency dual circularly polarized Fabry-Perot cavity MIMO antenna is: the first dielectric plate is placed at the bottom, the second dielectric plate is located above the first dielectric plate, the third dielectric plate is located above the second dielectric plate, and the absorber is placed in the air cavity between the first dielectric plate and the third dielectric plate.

[0020] In summary, the dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna provided by the present invention uses a microstrip feeder on the lower surface of the first dielectric plate to simultaneously couple the slotted ground on the upper surface and the single-sided copper-clad structure antenna of the second dielectric plate as an excitation source to form a dual-frequency resonance; the single-layer dielectric substrate is used as a reflective cover of the feeding antenna to achieve high gain and dual circular polarization; the fourth dielectric plate, the fifth dielectric plate, the sixth dielectric plate and the seventh dielectric plate form an absorber to enhance the isolation of the MIMO antenna. Finally, the MIMO antenna realizes left-hand circular polarization and right-hand circular polarization at low and high frequencies, respectively, and the realized 2-standing wave ratio bandwidth is 3.6% and 12.6%, of which the 3dB axial ratio bandwidth is 3% and 2% respectively, and the port isolation between the antenna units is better than 42.2dB in the entire working frequency band; at the same time, the cross-section of the MIMO antenna is only about 1 / 2 of the wavelength in vacuum.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] 1. Compared with the existing dual-frequency circularly polarized MIMO antenna, the present invention is the first to propose the ability to radiate different circularly polarized waves in two different frequency bands;

[0023] 2. The present invention relates to a single-layer partial reflector that can achieve gain improvement while realizing dual-band dual circular polarization conversion, and has higher gain and stable radiation pattern compared to the existing dual-band circular polarization MIMO antenna;

[0024] 3. The present invention has high port isolation, higher channel capacity and lower channel fading;

[0025] 4. The present invention has a simple structure and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0027] Figure 1 This is a structural cross-sectional view of a Fabry cavity MIMO antenna according to Embodiment 1 of the present invention.

[0028] Figure 2 It is a top view of the radiation patch of the feeding antenna structure according to embodiment 1 of the present invention.

[0029] Figure 3 A front view of the radiation patch of the feed antenna structure of embodiment 1 of the present invention

[0030] Figure 4 This is a three-dimensional diagram of the partial reflection surface unit of Example 1 of the present invention.

[0031] Figure 5 This is a top view of the top metal unit of the partial reflective surface of Example 1 of the present invention.

[0032] Figure 6 This is a top view of the bottom metal unit of the partial reflective surface of Example 1 of the present invention.

[0033] Figure 7 It is a three-dimensional diagram of the absorber unit of Example 1 of the present invention.

[0034] Figure 8 This is a top view of the absorber according to Example 1 of the present invention.

[0035] Fig. 9 1 is a reflection coefficient curve and a gain curve diagram of the feeding antenna of Example 1 of the present invention under HFSS simulation.

[0036] Fig.10 It is a graph showing the ratio of co-polarization transmission coefficient and cross-polarization transmission phase difference of the partial reflection surface unit of Example 1 of the present invention under HFSS simulation.

[0037] Fig.11 Circular polarization transmission coefficient of the partial reflection surface unit of Example 1 of the present invention under HFSS simulation.

[0038] Fig.12 It is a reflection coefficient and absorptivity curve diagram of the absorber unit of Example 1 of the present invention under HFSS simulation.

[0039] Fig.13 This is a reflection coefficient curve diagram of the MIMO antenna of Example 1 of the present invention under HFSS simulation.

[0040] Fig.14This is an S parameter curve diagram of the MIMO antenna of Example 1 of the present invention under HFSS simulation.

[0041] Fig.15 1 is a gain curve and an axial ratio curve of the MIMO antenna of Example 1 of the present invention under HFSS simulation.

[0042] Fig.16 This is the H-plane radiation pattern of the MIMO antenna of Example 1 of the present invention at 3.4 GHz under HFSS simulation.

[0043] Fig.17 This is the E-plane radiation pattern of the MIMO antenna of Example 1 of the present invention at 3.4 GHz under HFSS simulation.

[0044] Fig.18 This is the H-plane radiation pattern of the MIMO antenna of Example 1 of the present invention at 6.6 GHz under HFSS simulation.

[0045] Fig.19 This is the E-plane radiation pattern of the MIMO antenna of Example 1 of the present invention at 6.6 GHz under HFSS simulation.

[0046] Fig. 20 These are basic steps for designing a dual-frequency dual circularly polarized Fabry-Perot cavity MIMO antenna according to Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0047] 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.

[0048] Embodiment 1:

[0049] like Figure 1 As shown, a dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna provided by the present invention comprises: a feeding antenna, a reflective cover plate arranged above the feeding antenna, and an absorber between antenna units.

[0050] The feeding antenna is a first dielectric substrate 3 with copper cladding on both sides, with a microstrip feed line 1 engraved on the lower surface and a slotted copper ground plane 2 on the upper surface, and a second dielectric plate 4 of the feeding antenna with copper cladding 5 on the lower surface.

[0051] The partial reflection surface is composed of a copper-clad third dielectric substrate 14. The bottom surface of the third dielectric substrate 14 is provided with three metal strip structures 12, and the upper surface of the third dielectric substrate 14 is provided with an "I"-shaped copper-clad structure 13.

[0052] Furthermore, the feeding antenna is fed by a microstrip, the microstrip is connected to the SMA feeding from the side, the dielectric substrate 1 and the dielectric substrate 2 are separated by a certain distance, and two working frequency bands are generated by coupling.

[0053] Furthermore, the fourth dielectric plate 9 and the fifth dielectric plate 10 of the absorber have the fourth dielectric plate 9 with copper cladding 8 on the lower surface and a circular open ring 7 on the upper surface, and the fifth dielectric plate 10 with a circular open ring 6 on the upper surface and a 150Ω resistor 11.

[0054] Furthermore, the MIMO antennas are arranged with a 90° rotation.

[0055] like Figure 3 As shown, in this embodiment, the feed line of the feed antenna is 1, the slotted ground is 2, and the patch on the lower surface of the second dielectric plate is 5, so that it exhibits more free variables; in addition, the dielectric substrate 2 is introduced to be separated from the dielectric substrate 1 by a certain distance, and two working broadbands are generated through microstrip coupling. By designing the impedance of the microstrip line and setting these variables, good impedance matching of the broadband is achieved.

[0056] Further, if Figure 2 As shown, the first dielectric substrate 3 is provided with a plurality of fixing holes. Correspondingly, in this embodiment, fixing holes are respectively provided at the four vertex positions of the second dielectric substrate 4. The distance between the fixing holes and the second dielectric substrate 4 and the margin can be determined according to the actual situation. The margin distance has a very small effect on the performance of the antenna and only plays a supporting role. One end of the nylon dielectric support column is fixedly set in the positioning hole on the second dielectric substrate 4, and the other end is fixedly set in the positioning hole corresponding to the first dielectric substrate 3 on the feeding antenna, so that the second dielectric substrate 4 is placed above the slotted ground.

[0057] Further, if Figure 1 As shown, the interval between the third dielectric substrate 14 and the first dielectric substrate 3 is approximately 1 / 2 of the antenna's low-frequency operating wavelength.

[0058] like Figure 1 As shown, part of the reflective surface of the dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna is a copper-clad third dielectric plate 14. Figure 4 As shown, there are three strips of metal 12 on the bottom surface of the third dielectric substrate 14; Figure 4 As shown, the upper layer is coated with an "I"-shaped metal structure 13. Figure 5 As shown, a plurality of “I”-shaped structures 13 of the same size are periodically arranged above the third dielectric plate, as shown in FIG. Figure 6 As shown, a plurality of metal strips 12 of the same size are periodically arranged below the third dielectric substrate, and the copper-clad structure 12 on the bottom surface of the third dielectric substrate 14 and the copper-clad structure 13 on the top surface of the third dielectric substrate 14 are aligned in center.

[0059] In this embodiment, the dielectric constant of the third dielectric substrate 14 is 3.38 and the thickness is 1.52 mm. Figure 4 As shown, the side length l1 of the copper-clad structure 12 on the bottom surface of the third dielectric substrate 14 is 26 mm, the width w1 is 1.8 mm, and the interval g is 8.2 mm. The length d1 of the two sections of the "I"-shaped structure on the upper surface of the third dielectric substrate 14 is 10.4 mm, the width d w is 1.8mm, and the middle length d2 is 16.9mm. Figure 5 As shown, the copper-clad structures of the third dielectric substrate 14 are arranged periodically in a plane, and the center spacing p between two adjacent copper-clad structures is 26 mm.

[0060] In this embodiment, the dielectric constant of the sixth dielectric substrate 9 is 4.4 and the thickness is 4 mm, the dielectric constant of the seventh dielectric plate 10 is 4.4 and the thickness is 4 mm, the dielectric constant of the fourth dielectric substrate 17 is 4.4 and the thickness is 4 mm, and the dielectric constant of the fifth dielectric plate 18 is 4.4 and the thickness is 4 mm.

[0061] Further, if Figure 7 As shown, the lower surface of the sixth dielectric plate is fully covered with copper 8, and the side length is p a The inner radius r1 of the metal opening ring 7 on the upper surface of the sixth dielectric plate is 8.3 mm, and the width w a The inner radius r2 of the metal opening ring 6 on the upper surface of the seventh dielectric plate is 6.5 mm, and the width w is 1 mm. a The opening position is 1mm, the opening position is rotated 45° relative to the ring 7 and opened at 90° intervals, the opening width s is 1mm, and a 150Ω resistor is placed at the opening position. The inner radius r1 of the metal opening ring 15 on the lower surface of the fifth dielectric plate is 8.3mm, and the width w a The inner radius r2 of the metal opening ring 16 on the lower surface of the fourth dielectric plate is 6.5 mm, and the width w is 1 mm. a The opening position is 1 mm, the opening position is rotated 45° relative to the ring 15 and opened at intervals of 90°, the opening width s is 1 mm, and a 150Ω resistor is placed at the opening position.

[0062] Further, if Figure 7 As shown, the fourth dielectric plate and the seventh dielectric plate have holes 19, which are located at the positions of the fifth dielectric plate and the sixth dielectric plate resistors. The opening positions of ring 6 and ring 16 are the same, the opening positions of ring 7 and ring 15 are the same, and the through holes of the fourth dielectric plate and the seventh dielectric plate are at the same position. Figure 8As shown, the copper-clad structures of the sixth dielectric substrate 9 and the seventh dielectric substrate 10 are arranged periodically in a plane, and the center spacing between two adjacent copper-clad structures is p. a Both are 21mm.

[0063] In other preferred embodiments of the present invention, if the third dielectric substrate 14 uses other types of circuit boards, according to the above-mentioned design theory, the sizes of the copper-clad structures 12 and 13 of the third dielectric board 14 will be different accordingly, but the changes in these parameters are related to the dielectric constant of the third dielectric substrate 14 used.

[0064] In other preferred embodiments of the present invention, if the fourth dielectric substrate 9 and the fifth dielectric board 10 are other types of circuit boards, according to the above-mentioned design theory, the size of the copper clad structure 7 of the fourth dielectric board 9 and the copper clad structure 6 of the fifth dielectric board 10 and the model of the resistor 11 will be different accordingly, but the changes in these parameters are related to the dielectric constants of the fourth dielectric substrate 9 and the fifth dielectric board 10 used.

[0065] In summary, the dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna provided by the present invention uses a microstrip feeder on the lower surface of the first dielectric plate to simultaneously couple the slotted ground on the upper surface and the single-sided copper-clad structure antenna of the second dielectric plate as an excitation source to form a dual-frequency resonance; the single-layer dielectric substrate is used as a reflective cover plate of the feeding antenna to achieve high gain and dual circular polarization; the fourth dielectric plate and the fifth dielectric plate form an absorber to enhance the isolation of the MIMO antenna. Finally, the MIMO antenna realizes left-hand circular polarization and right-hand circular polarization at low and high frequencies, respectively, and the realized 2-standing wave ratio bandwidth is 3.6% and 12.6%, of which the 3dB axial ratio bandwidth is 3% and 2% respectively, and the port isolation between the antenna units is better than 45dB in the entire working frequency band; at the same time, the cross-section of the MIMO antenna is only about 1 / 2 of the wavelength in vacuum.

[0066] like Fig. 9 As shown, they are respectively a reflection coefficient curve and a gain curve of a feeding antenna of a dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna of the present invention. The simulation results show that the feeding antenna can achieve a standing wave ratio bandwidth below 2 of 3.6% and 12.6% in low-frequency and high-frequency distributions, and the gains are 1.48dBi-3.46dBi and 5.65dBi-8.4dBi respectively within the matching bandwidth.

[0067] like Fig.10As shown, it is the amplitude ratio and phase difference of the co-polarization transmission coefficient and the cross-polarization transmission coefficient of the partial reflection surface in the present invention. It can be seen that at 3.55 GHz and 7 GHz, the amplitude ratio is 0.87 and 1.07 respectively, and the phase difference is 90° and -90° respectively, which indicates that the linearly polarized wave is converted into a left-hand circularly polarized wave at 3.55 GHz and can be converted into a right-hand circularly polarized wave at 7 GHz.

[0068] like Fig.11 As shown in the figure, it is the transmission coefficient of the linear polarization wave to the circular polarization wave of the partial reflection surface in the present invention. It can be seen that at 3.55GHz, T +y is 0.16, T -y is 0.5, the right-hand circularly polarized wave is significantly smaller than the left-hand circularly polarized wave; at 7GHz, T +y is 0.84, T -y is 0.01, so the left-hand circularly polarized wave is suppressed and the right-hand circularly polarized wave is transmitted.

[0069] like Fig.12 As shown in FIG. 1 , the reflection coefficient and absorptivity of the absorber in the present invention are shown. It can be seen that in the broadband range of 3-7.7 GHz, the reflection coefficient is lower than -10 dB and the absorptivity is higher than 90%.

[0070] like Fig.13 As shown, it is a standing wave ratio curve of a dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna of the present invention, and it can be observed that the working bandwidth is 3.3-3.42 GHz (3.6%) and 6.15-6.96 GHz (12.6%).

[0071] like Fig.14 As shown, it is a port isolation curve of a dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna of the present invention. It can be observed that the port isolation is better than 42.2dB in 3.3-3.42GHz and better than 43.6dB in 6.15-6.96GHz.

[0072] like Fig.15 As shown, the axial ratio and gain curves of a dual-frequency, dual circularly polarized, high-isolation Bli-Perot cavity MIMO antenna of the present invention, it can be observed that the 3dB axial ratio bandwidth is 3.33-3.43GHz (3%) and 6.53-6.66GHz (2%), and the gain is 5dBi-7.9dBi and 9.24dBi-10.8dBi in the low-frequency and high-frequency axial ratio bandwidths, respectively.

[0073] like Fig.16As shown, this is the H-plane radiation pattern of a dual-frequency, dual circularly polarized, high-isolation Bli-Perot cavity MIMO antenna of the present invention at 3.4 GHz. It can be observed that the main radiation direction is left-hand circular polarization, and the difference between the two circular polarizations is greater than 20 dB.

[0074] like Fig.17 As shown, this is the E-plane radiation pattern of a dual-frequency, dual circularly polarized, high-isolation Bli-Perot cavity MIMO antenna of the present invention at 3.4 GHz. It can be observed that the main radiation direction is left-hand circular polarization, and the difference between the two circular polarizations is greater than 20 dB.

[0075] like Fig.18 As shown, this is the H-plane radiation pattern of a dual-frequency, dual circularly polarized, high-isolation Bli-Perot cavity MIMO antenna of the present invention at 6.6 GHz. It can be observed that the main radiation direction is right-hand circular polarization, and the difference between the two circular polarizations is greater than 20 dB.

[0076] like Fig.19 As shown, this is the E-plane radiation pattern of a dual-frequency, dual circularly polarized, high-isolation Bli-Perot cavity MIMO antenna of the present invention at 6.6 GHz. It can be observed that the main radiation direction is right-hand circular polarization, and the difference between the two circular polarizations is greater than 20 dB.

[0077] like Fig. 20 As shown, the basic process of manufacturing a dual-frequency, dual circular polarization, high-isolation Bli-Perot cavity MIMO antenna of the present invention.

[0078] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as limiting the present invention. After reading the above content, various modifications and substitutions of the present invention will be obvious to those skilled in the art. Therefore, any modification, equivalent substitution, improvement, etc. made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna, characterized in that: It includes: a patch-type feeding antenna and a partial reflection surface composed of a metal strip structure and an "I"-shaped structure above the patch-type feeding antenna, which is combined into a Fabry-Perot cavity antenna unit, and a circular ring structure absorber between the antenna units; The feeding antenna is composed of a first dielectric substrate with copper clad on both sides and a second dielectric substrate with copper clad on one side. A microstrip feed line is engraved on the lower surface of the first dielectric substrate, and a metal ground plane with a slit is formed on the upper surface, wherein the size of the metal ground plane is the same as that of the partial reflection surface. The second dielectric substrate is located directly above the first dielectric substrate, and a rectangular patch is engraved on the lower surface of the second dielectric substrate, which is equivalent to the microstrip feed line of the first dielectric plate exciting the slit ground while coupling the rectangular patch to form two resonance points. The partial reflection surface is located above the feed antenna and is composed of a third dielectric plate with copper clad on both sides. An "I"-shaped structure is engraved on the upper surface of the third dielectric plate. The "I"-shaped structure is deflected by 45 degrees, and three metal strips are engraved on the lower surface. The absorber is composed of a fifth dielectric plate and a sixth dielectric plate with double-sided copper cladding, and a fourth dielectric plate and a seventh dielectric plate with single-sided copper cladding, wherein the top layer of the fifth dielectric plate is fully copper clad, the bottom layer is an open circular ring structure, and the openings are connected by resistors; the bottom layer of the fourth dielectric plate is an open circular ring structure, the openings are connected by resistors, and a through hole is punched in the fourth dielectric plate, and the position of the through hole is the position where the resistor of the fifth dielectric plate is placed; the bottom layer of the sixth dielectric plate is fully copper clad, the top layer is an open circular ring structure, and the openings are connected by resistors; the top layer of the seventh dielectric plate is an open circular ring structure, the openings are connected by resistors, and a through hole is punched in the seventh dielectric plate, and the position of the through hole is the position where the resistor of the sixth dielectric plate is placed.

2. A dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 1, characterized in that: The specific structure of the absorber is as follows: the bottom layer of the fifth dielectric plate is a circular ring structure, with four openings spaced 90° apart on the ring, and the four openings are connected with four 150Ω patch resistors; the bottom layer of the fourth dielectric plate is a circular ring structure, which is smaller than the top layer of the fifth dielectric plate, with four openings spaced 90° apart on the ring, and the four openings are connected with four 150Ω patch resistors, wherein the position of the opening is rotated 45° relative to the position of the opening on the upper layer of the fifth dielectric plate, and four through holes are punched in the fourth dielectric plate, and the position of the through holes is the position where the resistors of the fourth dielectric plate are placed; the bottom layer of the sixth dielectric plate is fully copper-clad, and the top layer is a circular ring structure, with four openings spaced 90° apart on the ring, and the four The openings are connected with four 150Ω chip resistors; the top layer of the seventh dielectric plate is a circular ring structure, which is smaller than the circular ring on the top layer of the sixth dielectric plate, and four openings are spaced 90° apart on the ring, and the four openings are connected with four 150Ω chip resistors, wherein the positions of the openings are rotated 45° relative to the positions of the openings on the upper layer of the sixth dielectric plate, and four through holes are punched in the seventh dielectric plate, and the positions of the through holes are the positions where the resistors of the fourth dielectric plate are placed; the circular rings of the fourth dielectric plate and the seventh dielectric plate are consistent in size and opening position; the circular rings of the fifth dielectric plate and the sixth dielectric plate are consistent in size and opening position; there is no gap between the fourth dielectric plate, the fifth dielectric plate, the sixth dielectric plate and the seventh dielectric plate.

3. The dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 1, characterized in that: The distance between the ground plane of the feeding antenna and the third dielectric substrate of the partial reflection surface is hc, and the initial value is 1 / 2 of the antenna low-frequency band working wavelength. By optimizing the distance hc, the optimal gain and axial ratio bandwidth are ensured.

4. The dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 3, characterized in that: The lower surface of the third dielectric substrate is periodically arranged with a strip-shaped metal copper structure; the upper surface of the third dielectric substrate is periodically arranged with a plurality of "I"-shaped patch structures of the same size.

5. The dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 3, characterized in that: The lower surface of the fourth dielectric plate is periodically arranged with open rings and resistors; the lower surface of the fifth dielectric plate is periodically arranged with open rings and resistors; the upper surface of the sixth dielectric plate is periodically arranged with open rings and resistors, and the lower surface is completely copper-clad; the upper surface of the seventh dielectric plate is periodically arranged with open rings and resistors.

6. The dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 2, characterized in that: The dielectric constant of the first dielectric substrate of the partial reflection surface is 3.38 and the thickness is 0.81 mm. The dielectric constant of the second dielectric substrate is 3.38 and the thickness is 0.81 mm.

7. The dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 2, characterized in that: The third dielectric plate has a dielectric constant of 3.38 and a thickness of 1.52 mm. The second dielectric substrate has a dielectric constant of 3.38 and a thickness of 0.5 mm.

8. The dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 2, characterized in that: The fourth dielectric plate shown has a dielectric constant of 4.4 and a thickness of 4 mm, and the fifth dielectric plate has a dielectric constant of 4.4 and a thickness of 4 mm.

9. The dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 1, characterized in that: The processing steps include: Step 1: Place a partial reflective surface above the patch-type feed antenna to form an antenna unit, wherein the partial reflective surface is composed of a metal strip structure and an "I"-shaped structure; Step 2: Rotate the antenna units 90° to form a 2×2 MIMO antenna array; Step 3: Add circular ring structure absorbers between each unit.

10. The processing steps of a dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 9, characterized in that: The first dielectric substrate is provided with a plurality of fixing holes, and the second dielectric substrate is provided with a plurality of fixing holes corresponding to the openings of the first dielectric substrate. One end of the nylon dielectric support column is fixedly set in the fixing hole of the first dielectric plate, and the other end is fixedly set in the fixing hole of the second dielectric plate, so that the second dielectric plate is supported and placed above the slotted metal ground; a partial reflecting surface is placed above the feeding antenna, and the two form an antenna unit, and the antenna units are rotated 90 degrees to form a 2×2 MIMO antenna; the specific method for placing the absorber is as follows: the absorber forms a cross array and is placed between four antenna units to fix the feed antenna and the partial reflecting surface, and the partial reflecting surface is supported and placed directly above the feeding antenna.

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