CN114843772A - A dual frequency, dual circular polarization, high isolation Fabry-Perot cavity MIMO antenna and its processing method - Google Patents

Abstract

The invention discloses a 2×2 dual-frequency, dual-circular polarization, high-isolation Fabry-Perot cavity multi-input and multi-output antenna and a processing method, which belong to the technical field of antennas. It consists of four identical Fabry cavity antenna elements arranged with a 90° rotation. The antenna unit consists of a feeding antenna and a partial reflecting surface. The feed antenna is a hybrid structure of slot and patch. The chiral metamaterial acts as a partially reflective surface unit to realize left-handed circularly polarized waves and right-handed circularly polarized waves. The introduction of broadband metamaterial absorbers improves the port isolation between adjacent antenna elements. The antenna array has the characteristics of high isolation, high gain, dual frequency bands and dual circular polarization, and is suitable for modern mobile communication applications. The processing method includes the following steps: pre-processing the feeding antenna; processing part of the reflecting surface; processing the wave absorbing body; placing the partial reflecting surface above the feeding antenna to form an antenna unit; rotating and arranging the antenna unit to form a MIMO Antenna array; place absorbers between elements.

Description

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

technical field

The invention relates to the technical field of antenna engineering, in particular to a dual-band, dual-circular polarization, and high-isolation Fabry-Perot cavity MIMO antenna.

Background technique

Multiple-input multiple-output antennas, also known as MIMO antennas. Compared with the traditional single antenna, it has the ability to greatly improve the data rate and channel capacity without occupying additional bandwidth, so it has received extensive attention in the field of antennas. MIMO antennas have potential applications in current and next-generation wireless communication systems, sensor systems, radar, and satellite communications.

MIMO antennas are widely used in wireless communication and other fields due to their characteristics of increasing spatial freedom, improving system performance, and improving channel capacity. been widely developed. In recent years, a lot of research has been done on dual-frequency circularly polarized MIMO antennas, and the ways to achieve dual-frequency circular polarization can be roughly divided into three categories. (1) The patch antenna method, by opening orthogonal slits, circular slits, and cutting corners in the patch antenna, changes the distribution of the current on the patch to achieve circular polarization. However, such antennas usually have a narrower axial ratio bandwidth and lower gain, which is due to the radiation mechanism of the patch antenna itself. (2) Phase delay method: This method divides the signal into two signals with equal amplitude and 90 degrees phase difference through a 90-degree power divider, and excites two orthogonal polarizations of a dual-frequency dual-linear polarized antenna. The input end, thereby forming circularly polarized radiation. Although this method can achieve a wide axial ratio bandwidth, it introduces an additional feeding structure, which leads to the complexity of the entire MIMO antenna feeding system. (3) Polarization conversion method: The polarization conversion cover is loaded on the linearly polarized antenna to realize the conversion of the linearly polarized wave to the circularly polarized wave, and the planned conversion cover can also act as a partial reflection surface to improve the gain.

To sum up, the traditional circularly polarized MIMO antenna has problems such as narrow axial ratio bandwidth and low gain, and in the future wireless communication systems will require wider axial ratio bandwidth, higher gain and lower delay. Therefore, it is of great practical significance to study dual-frequency, dual-circularly polarized, and high-isolation MIMO antennas.

SUMMARY OF THE INVENTION

At present, the published circularly polarized MIMO antennas either have insufficient gain and axial ratio bandwidth, which limits their application scope, or insufficient isolation, which deteriorates system performance and lacks practicability.

The technical problem to be solved by the present invention is: by loading part of the reflective surface, the purpose is to improve the gain of the feed antenna and realize the polarization conversion of dual frequencies, and then form a MIMO antenna in the form of an array, and by loading the absorbing body to improve each The isolation between units is the first to propose MIMO antennas working in two frequency bands with different circular polarization forms, and achieve high isolation.

The present invention is achieved through the following technical solutions:

A dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna, comprising a feed antenna, a partial reflection surface and a wave absorber. Among them, part of the reflective surface is covered above the feed antenna, which is used to improve the gain of the feed antenna and realize polarization conversion. The feed antenna and part of the reflective surface form an antenna unit, and the antenna unit is arranged in a 90° rotation to form a MIMO antenna. The wave body is loaded between the antenna elements to improve the isolation of the MIMO antenna.

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

A high-gain dual-frequency circularly polarized Fabry cavity antenna is obtained by covering a part of the reflective surface above the feed antenna. The part of the reflective surface has a high reflection coefficient and dual-frequency polarization conversion function at the same time, which is different from the general dual-frequency polarization conversion function. The difference between the frequency circularly polarized antenna is that the present invention only needs one feed port to excite the dual-frequency linearly polarized antenna. When the linearly polarized wave reaches the partial reflecting surface, a part of the electromagnetic wave is reflected back to the floor, and the reflected electromagnetic wave passes through the ground. The reflection reaches the partial reflecting surface again; therefore, the electromagnetic wave is reflected multiple times in the cavity to achieve the in-phase superposition of the electric field, and finally transmits out part of the reflecting surface, thereby realizing the enhancement of the feed antenna gain, and the transmitted electromagnetic wave is circularly polarized. form radiation to achieve polarization conversion.

The advantage of choosing a patch-type feed antenna is that the patch antenna has the structural features of 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.

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

As a further description of the present invention, the above-mentioned partial reflection surface covering the patch antenna includes a single-layer dielectric base with a double-layer printed metal structure.

As a further description of the present invention, the above-mentioned wave absorbing body loaded between the antenna units includes: the bottom layer of the fifth dielectric plate is a circular ring structure, the ring is separated by 4 ports at 90° intervals, and the 4 ports use four 150Ω The bottom layer of the fourth dielectric board is a circular ring structure, which is smaller than the top ring of the fifth dielectric board. The ring is separated by 4 ports at 90° intervals, and the 4 ports are connected with 4 150Ω Chip resistor connection, in which the position of the opening is rotated 45° relative to the opening position of the upper layer of the fifth dielectric board, and the fourth dielectric board is punched with 4 through holes, and the position of the through holes is the position where the resistors of the fourth dielectric board are placed; the sixth dielectric board The bottom layer of the board is fully coated with copper, the top layer is a circular ring structure, the ring is separated by 4 ports at 90° intervals, and the 4 ports are connected with four 150Ω chip resistors; the top layer of the seventh dielectric board is a circular ring structure, The ring is smaller than the ring on the top layer of the sixth dielectric board. There are 4 openings on the ring at 90° intervals, and the 4 openings are connected by four 150Ω chip resistors. The position of the opening is relative to the opening position of the upper layer of the sixth dielectric board. Rotate 45°, and punch 4 through holes on the seventh dielectric plate. The positions of the through holes are where the resistors of the fourth dielectric plate are placed. The ring size and opening position of the fourth medium plate and the seventh medium plate are the same; the ring size and opening position of the fifth medium plate and the sixth medium plate are the same. There is no gap between the fourth media plate, the fifth media plate, the sixth media plate and the seventh media plate.

As a further description of the present invention, the specific structure of the feed antenna of the dual-frequency, dual circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna is: the feeder structure on the lower surface of the first dielectric plate is SMA A single microstrip line is fed, and the end of the microstrip line is bifurcated into two microstrip lines; the central part of the copper-clad structure on the upper surface is opened with a rectangular gap; the center of the lower surface of the second dielectric plate is coated with a rectangle. The copper feeder stacks the first dielectric board and the second dielectric board in the order that the bottom layer is the first dielectric board and the top layer is the second dielectric board; wherein, the thickness of the first dielectric board and the second dielectric board are the same; the first dielectric board is the same thickness; The dielectric constant of the plate and the second dielectric plate are the same.

As a further description of the present invention, the slotted 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 correspondingly arranged concentrically.

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 positions of the fixing holes of the first dielectric plate. By fixing one end of the nylon medium support column in the fixing hole of the first medium plate and the other end in the fixing hole of the second medium plate, the second medium plate is supported and placed above the ground plane.

As a further description of the present invention, the specific structure of the wave 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 third The seven medium plates are stacked in sequence in the order that the bottom layer is the fourth medium plate, the next is the fifth medium plate, the sixth medium plate, and the top layer is the seventh medium plate. Then they are periodically arranged in a cross shape, and the length and width of the cross shape are both the sum of the two ground planes and the thicknesses of the four medium plates, the fifth medium plate, the sixth medium plate and the seventh medium plate. The thickness of the fourth dielectric plate, the fifth dielectric plate, the sixth dielectric plate and the seventh dielectric plate are the same, and the dielectric constants are the same.

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 as follows: the first dielectric plate is placed at the bottom, and the second dielectric plate is located above the first dielectric plate , the third dielectric plate is located above the second dielectric plate, and the position of the wave absorber is placed in the air cavity between the first dielectric plate and the third dielectric plate.

To sum up, the present invention provides a dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna, which uses the microstrip feeder on the lower surface of the first dielectric plate to simultaneously couple the upper surface with the slotted ground and the upper surface. The antenna of the single-sided copper-clad structure of the second dielectric plate is used as the excitation source to form dual-frequency resonance; the single-layer dielectric substrate is used as the reflective cover plate of the feeding antenna to achieve high gain and dual circular polarization; the fourth dielectric plate, the fifth The dielectric plate, the sixth dielectric plate and the seventh dielectric plate form a wave absorbing body to enhance the isolation of the MIMO antenna. The final MIMO antenna achieves left-handed circular polarization and right-handed circular polarization at low frequency and high frequency, respectively, and the achieved 2 standing wave ratio bandwidths are 3.6% and 12.6%, of which the 3dB axial ratio bandwidth is 3% and 2%, respectively. The port isolation between units is better than 42.2dB over the entire operating frequency band; at the same time, the cross-section of the MIMO antenna is only about 1/2 of the wavelength in vacuum.

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

1. Compared with the existing dual-frequency circularly polarized MIMO antenna, the present invention proposes for the first time that different circularly polarized waves can be radiated in two different frequency bands;

2. The present invention relates to a single-layer partial reflective surface that has the conversion of dual-band dual circular polarization while realizing gain improvement, and has higher gain and stable pattern compared to the existing dual-frequency circularly polarized MIMO antenna;

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

4. The present invention has a simple structure and is easy to implement.

Description of drawings

The accompanying drawings described herein are used to provide further understanding of the embodiments of the present invention, and constitute a part of the present application, and do not constitute limitations to the embodiments of the present invention. In the attached image:

FIG. 1 is a structural cross-sectional view of a Fabry cavity MIMO antenna according to Embodiment 1 of the present invention.

FIG. 2 is a top view of the radiating patch of the feed antenna structure according to Embodiment 1 of the present invention.

3 is a front view of the radiating patch of the feed antenna structure according to Embodiment 1 of the present invention

FIG. 4 is a three-dimensional view of a partially reflective surface unit according to Embodiment 1 of the present invention.

FIG. 5 is a top view of the top metal unit of the partially reflective surface according to Embodiment 1 of the present invention.

FIG. 6 is a top view of the bottom metal unit of the partially reflective surface according to Embodiment 1 of the present invention.

FIG. 7 is a three-dimensional view of the wave absorber unit according to Embodiment 1 of the present invention.

FIG. 8 is a top view of the wave absorber according to the first embodiment of the present invention.

FIG. 9 is a reflection coefficient curve and a gain curve diagram of the feed antenna according to Embodiment 1 of the present invention under HFSS simulation.

FIG. 10 is a graph showing the co-polarization and cross-polarization transmission coefficient ratios and transmission phase differences of the partially reflective surface unit under HFSS simulation according to Embodiment 1 of the present invention.

FIG. 11 is the circular polarization transmission coefficient of the partially reflective surface unit according to Embodiment 1 of the present invention under HFSS simulation.

FIG. 12 is a curve diagram of reflection coefficient and absorptivity of the wave absorber unit according to Embodiment 1 of the present invention under HFSS simulation.

FIG. 13 is a reflection coefficient curve diagram of the MIMO antenna according to Embodiment 1 of the present invention under HFSS simulation.

FIG. 14 is an S-parameter curve diagram of the MIMO antenna according to Embodiment 1 of the present invention under HFSS simulation.

FIG. 15 is a gain curve and an axial ratio curve diagram of the MIMO antenna according to Embodiment 1 of the present invention under HFSS simulation.

FIG. 16 is an H-plane pattern at 3.4 GHz under HFSS simulation of the MIMO antenna according to Embodiment 1 of the present invention.

FIG. 17 is an E-plane pattern at 3.4 GHz under HFSS simulation of the MIMO antenna according to Embodiment 1 of the present invention.

FIG. 18 is an H-plane pattern at 6.6 GHz under HFSS simulation of the MIMO antenna according to Embodiment 1 of the present invention.

FIG. 19 is an E-plane pattern at 6.6 GHz under HFSS simulation of the MIMO antenna according to Embodiment 1 of the present invention.

FIG. 20 shows the basic steps of designing a dual-frequency dual-circularly polarized Fabry-Perot cavity MIMO antenna according to Embodiment 1 of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and the accompanying drawings. as a limitation of the present invention.

Example 1:

As shown in FIG. 1 , a dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna provided by the present invention includes: a feeder antenna, a reflective cover plate disposed above the feeder antenna, and Absorber between antenna elements.

The feeding antenna is a first dielectric substrate 3 coated with copper on both sides, the lower surface of which is engraved with a microstrip feeder 1, the upper surface is made of slotted copper as the ground plane 2, and the second dielectric substrate 4 of the feeding antenna is , and the lower surface is coated with copper 5.

The partially reflective surface is made of a copper-clad third dielectric plate 14 . The bottom surface of the third dielectric substrate 14 is the three metal strip structures 12 , and the upper surface of the third dielectric substrate 14 is the “I” type copper-clad structure 13 .

Further, the feeding antenna adopts a microstrip for feeding, the microstrip is connected to the SMA feed from the side, and the dielectric substrate 1 and the dielectric substrate 2 are separated by a certain distance, and two operating frequency bands are generated through coupling.

Further, in the fourth dielectric plate 9 and the fifth dielectric plate 10 of the wave absorber, the lower surface of the fourth dielectric plate 9 is fully coated with copper 8, the upper surface is a circular open ring 7, and the upper surface of the fifth dielectric plate 10 is circular Split ring 6, 150Ω resistor 11.

Further, the MIMO antennas are arranged in a 90° rotation.

As shown in FIG. 3 , in this embodiment, the feed line of the feeding 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; The introduction of the second dielectric substrate and the first dielectric substrate is separated by a certain distance, and two working broadbands are generated through microstrip coupling. Good impedance matching over a wide frequency band is achieved by designing the impedance of the microstrip line and by setting these variables.

Further, as shown in FIG. 2 , the first dielectric substrate 3 is provided with a plurality of fixing holes. Correspondingly, in this embodiment, fixing holes are respectively opened at four corner positions of the second dielectric substrate 4 . The margin distance between the fixing hole and the second dielectric substrate 4 can be determined according to the actual situation, and the margin distance has little influence on the performance of the antenna and only plays a supporting role. By fixing one end of the nylon dielectric support column in the positioning hole on the second dielectric substrate 4 and the other end in the positioning hole corresponding to the first dielectric substrate 3 on the feeding antenna, the second dielectric plate 4 makes the It is placed above the slotted ground.

Further, as shown in FIG. 1 , the interval between the third dielectric substrate 14 and the first dielectric plate 3 is approximately 1/2 of the operating wavelength of the antenna in the low frequency band.

As shown in FIG. 1 , part of the reflection surface of the dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna is a third dielectric plate 14 coated with copper. As shown in FIG. 4 , there are three strip-shaped metals 12 on the bottom surface of the third dielectric substrate 14 ; as shown in FIG. 4 , an “I”-shaped metal structure 13 is coated on the upper layer. As shown in FIG. 5 , a plurality of “I”-shaped structures 13 with the same size are periodically arranged above the third dielectric plate. As shown in FIG. 6 , a plurality of strip-shaped metals 12 with the same size are periodically arranged on the third dielectric plate. under the media plate. Moreover, the copper clad structure 12 on the bottom surface of the third dielectric substrate 14 and the copper clad structure 13 on the upper surface of the third dielectric substrate 14 are aligned at the center.

In this embodiment, the dielectric constant of the third dielectric substrate 14 is 3.38 and the thickness is 1.52 mm. As shown in FIG. 4 , the length l ₁ of the side of the copper-clad structure 12 on the bottom surface of the third dielectric substrate 14 is 26 mm, the width w ₁ is 1.8 mm, and the interval g is 8.2 mm. The length d ₁ 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 1.8 mm, and the middle length d ₂ is 16.9 mm. As shown in FIG. 5 , the copper-clad structures of the third dielectric substrate 14 are periodically arranged in a plane, and the center-to-center spacing p between two adjacent copper-clad structures is both 26 mm.

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 substrate 10 is 4.4 and the thickness is 4 mm, and the fourth dielectric substrate 17 has a dielectric constant of 4.4 and a thickness of 4 mm. The dielectric constant 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.

Further, as shown in FIG. 7 , the lower surface of the sixth dielectric plate is fully coated with copper 8, the side length p _a is 21 mm, and the inner radius r ₁ of the metal open ring 7 on the upper surface of the sixth dielectric plate is 8.3 mm, The width _wa is 1mm, the openings are at 90° intervals, the opening width s is 1mm, and the 150Ω resistor 11 is placed at the opening position. The inner radius r ₂ of the metal opening ring 6 on the upper surface of the seventh medium plate is 6.5mm, the width w _a is 1mm, the opening position is rotated 45° relative to the ring 7 and the opening is at 90° intervals, and the opening width s is 1mm , 150Ω resistor is placed in the opening position. The inner radius r ₁ of the metal opening ring 15 on the lower surface of the fifth dielectric plate is 8.3 mm, the width _wa is 1 mm, the openings are at 90° intervals, the opening width s is 1 mm, and a 150Ω resistor is placed at the opening position. The inner radius r ₂ of the metal opening ring 16 on the lower surface of the fourth dielectric plate is 6.5mm, the width _wa is 1mm, the opening position is rotated 45° relative to the ring 15 and the opening is at an interval of 90°, and the opening width s is 1mm. , 150Ω resistor is placed in the opening position.

Further, as shown in FIG. 7 , holes 19 are opened on the fourth dielectric plate and the seventh dielectric plate, and the positions are the positions where the resistors of the fifth dielectric plate and the sixth dielectric plate are located. The opening positions of the ring 6 and the ring 16 are the same, the opening positions of the ring 7 and the ring 15 are the same, and the opening positions of the fourth dielectric plate and the seventh dielectric plate are the same. As shown in FIG. 8 , the copper-clad structures of the sixth dielectric substrate 9 and the seventh dielectric plate 10 are periodically arranged in a plane, and the center-to-center spacing p _a between two adjacent copper-clad structures is both 21 mm.

In other preferred embodiments of the present invention, if other types of circuit boards are selected for the third dielectric substrate 14, according to the above design theory, the dimensions of the copper-clad structures 12 and 13 of the third dielectric substrate 14 will be different accordingly, but The changes of these parameters are all related to the dielectric constant of the third dielectric substrate 14 used.

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

To sum up, the present invention provides a dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna, which uses the microstrip feeder on the lower surface of the first dielectric plate to simultaneously couple the upper surface with the slotted ground and the upper surface. The antenna of the single-sided copper-clad structure of the second dielectric plate is used as the excitation source to form dual-frequency resonance; the single-layer dielectric substrate is used as the reflective cover plate of the feeding antenna to achieve high gain and dual circular polarization; the fourth dielectric plate and the fifth The dielectric plate forms a wave absorber to enhance the isolation of the MIMO antenna. The final MIMO antenna achieves left-handed circular polarization and right-handed circular polarization at low frequency and high frequency, respectively, and the achieved 2 standing wave ratio bandwidths are 3.6% and 12.6%, of which the 3dB axial ratio bandwidth is 3% and 2%, respectively. The port isolation between units is better than 45dB over the entire operating frequency band; meanwhile, the cross-section of the MIMO antenna is only about 1/2 of the wavelength in vacuum.

As shown in FIG. 9 , the reflection coefficient curve and gain curve of the feed antenna of a dual-frequency, dual-circularly polarized, and high-isolation Fabry-Perot cavity MIMO antenna of the present invention are respectively shown. The simulation results show that the feeding The antenna can achieve 3.6% and 12.6% VSWR bandwidths below 2 at low and high frequency distributions, with gains of 1.48dBi-3.46dBi and 5.65dBi-8.4dBi within the matching bandwidth, respectively.

As shown in Figure 10, it is the amplitude ratio and phase difference of the co-polarized transmission coefficient and the cross-polarized transmission coefficient of the partially reflecting surface in the present invention. It can be seen that at 3.55 GHz and 7 GHz, the amplitude ratios are 0.87 and 1.07, respectively, The phase differences are 90° and -90°, respectively, which indicates that the linearly polarized waves are converted into left-hand circularly polarized waves at 3.55 GHz, and can be converted into right-handed circularly polarized waves at 7 GHz.

As shown in Figure 11, it is the transmission coefficient of the partially reflective surface linearly polarized wave to the circularly polarized wave in the present invention. It can be seen that at 3.55 GHz, T _{+ y} is 0.16, T _-y is 0.5, and the right-handed circular polar The chemical wave is obviously smaller than the left-handed circularly polarized wave; at 7 GHz, T _+y is 0.84, and T _-y is 0.01, so the left-handed circularly polarized wave is suppressed at this time, and the transmission is a right-handed circularly polarized wave.

As shown in Fig. 12, which is the reflection coefficient and absorption rate of the wave absorber in the present invention, it can be seen that the reflection coefficient is lower than -10dB and the absorption rate is higher than 90% in the broadband range of 3-7.7GHz.

As shown in FIG. 13, it is the VSWR curve of a dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna of the present invention. 6.15-6.96GHz (12.6%) operating bandwidth.

As shown in FIG. 14, it is the port isolation 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 it is better than 42.2dB within 3.3-3.42GHz port isolation and better than 43.6dB port isolation within 6.15-6.96GHz.

As shown in FIG. 15 , it is the axial ratio and gain curve of a dual-frequency, dual-circular polarization method, and high-isolation Brie-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%), the gain is 5dBi-7.9dBi and 9.24dBi-10.8dBi in the low-frequency and high-frequency axial ratio bandwidths, respectively.

As shown in FIG. 16 , it is the H-plane pattern of a dual-frequency, dual-circular polarization, and high-isolation Brie-Perot cavity MIMO antenna at 3.4 GHz. It can be observed that the main radiation direction is left-handed circular pole. , the difference between the two circular polarizations is higher than 20dB.

As shown in FIG. 17, it is the E-plane pattern of a dual-frequency, dual-circular polarization method, and high-isolation Brie-Perot cavity MIMO antenna at 3.4 GHz. It can be observed that the main radiation direction is left-handed circular pole. , the difference between the two circular polarizations is higher than 20dB.

As shown in FIG. 18 , it is the H-plane pattern of a dual-frequency, dual-circular polarization, and high-isolation Brie-Perot cavity MIMO antenna at 6.6 GHz. It can be observed that the main radiation direction is a right-handed circle. polarization, the difference between the two circular polarizations is higher than 20dB.

As shown in FIG. 19 , it is the E-plane pattern of a dual-frequency, dual-circular polarization, and high-isolation Brie-Perot cavity MIMO antenna at 6.6 GHz. It can be observed that the main radiation direction is a right-handed circle. polarization, the difference between the two circular polarizations is higher than 20dB.

As shown in FIG. 20 , it is a basic process of processing a dual-frequency, dual-circular polarization, and high-isolation Brie-Perot cavity MIMO antenna according to the present invention.

While the content of the present invention has been described in detail by way of the above preferred embodiments, it should be appreciated that the above description should not be construed as limiting the present invention. Various modifications and alternatives to the present invention will be apparent to those skilled in the art upon reading the foregoing. Therefore, any modification, equivalent replacement, improvement, etc. made within the principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a dual-frequency, dual-circular polarization, high isolation Fabry-Perot cavity MIMO antenna, is characterized in that, comprising: the feed antenna and the partial reflection surface above it are combined into a Fabry-Perot cavity antenna unit , and the absorber between the antenna elements. The feeding antenna is composed of a first dielectric substrate coated with copper on both sides and a second dielectric substrate coated with copper on one side. The ground plane, where the metal ground is the same size as the partially reflective 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 feeder of the first dielectric plate. resonance point. The part of the reflecting surface is located above the feeding antenna, and is composed of a third dielectric plate coated with copper 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°, and three metal strips are engraved on the lower surface. The wave absorber is composed of the fifth and sixth dielectric plates coated with copper on both sides, and the fourth and seventh dielectric plates coated with copper on one side. Among them, the top layer of the fifth dielectric board is fully coated with copper, 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 a split circular ring structure, and the openings are connected by resistors, and the fourth dielectric plate is connected by resistors. The position of the through hole is the position where the resistors of the fifth dielectric plate are placed; the bottom layer of the sixth dielectric plate is fully coated with copper, 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 circle In the ring structure, the openings are connected by resistors, and the seventh dielectric plate is punched through holes, and the position of the through holes is the position where the sixth dielectric plate resistors are placed. 2. a kind of dual frequency, dual circular polarization, high isolation Fabry-Perot cavity MIMO antenna according to claim 1, is characterized in that, the concrete structure of described wave absorber is: the bottom layer of the fifth dielectric plate It is a circular ring structure, with 4 ports spaced at 90° intervals on the ring, and the 4 ports are connected with 4 150Ω chip resistors; the bottom layer of the fourth dielectric board is a circular ring structure, which is smaller than the fifth dielectric board. The top ring has 4 openings spaced at 90° intervals, and the 4 openings are connected with 4 150Ω SMD resistors. The dielectric board is punched with 4 through holes, and the position of the through holes is the position where the resistance of the fourth dielectric board is placed; the bottom layer of the sixth dielectric board is fully coated with copper, and the top layer is a circular ring structure, and the ring is separated by 4 openings at 90° intervals. , 4 ports are connected with 4 150Ω chip resistors; the top layer of the seventh dielectric board is a circular ring structure, the ring is smaller than the top ring of the sixth dielectric board, and 4 ports are separated by 90° on the ring, 4 Each port is connected with four 150Ω chip resistors, the position of the opening is rotated 45° relative to the opening position of the upper layer of the sixth dielectric board, and four through holes are punched in the seventh dielectric board, and the position of the through holes is the fourth dielectric board. where the resistors are placed. The ring size and opening position of the fourth medium plate and the seventh medium plate are the same; the ring size and opening position of the fifth medium plate and the sixth medium plate are the same. There is no gap between the fourth media plate, the fifth media plate, the sixth media plate and the seventh media plate. 3. a kind of dual frequency, dual circular polarization, high isolation Fabry-Perot cavity MIMO antenna according to claim 1, is characterized in that, the ground plane of described feed antenna and the part reflecting surface third The interval between the dielectric substrates is hc, and the initial value is 1/2 of the low-frequency operating wavelength of the antenna. By optimizing the distance hc, the optimal gain and axial ratio bandwidth are ensured. 4. A dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 3, wherein strips are periodically arranged on the lower surface of the third dielectric substrate A strip-shaped metal copper structure; a plurality of "I"-shaped patch structures of the same size are periodically arranged on the upper surface of the third dielectric substrate. 5. a kind of dual frequency, dual circular polarization, high isolation Fabry-Perot cavity MIMO antenna according to claim 3, is characterized in that, described fourth dielectric plate lower surface periodically arranges open ring and Resistors; open rings and resistors are periodically arranged on the lower surface of the fifth dielectric plate; open rings and resistors are periodically arranged on the upper surface of the sixth dielectric plate, and the bottom surface is fully copper-coated; the seventh dielectric plate The upper surface is periodically arranged with split rings and resistors. 6. A dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 2, wherein the first dielectric substrate of the partial reflection surface has a dielectric constant of 3.38, The thickness is 0.81mm, the dielectric constant of the second dielectric substrate is 3.38, and the thickness thereof is 0.81mm. 7. A dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 2, wherein the dielectric constant of the third dielectric plate is 3.38, and its thickness is 1.52mm, the dielectric constant of the second dielectric substrate is 3.38, and the thickness is 0.5mm. 8. a kind of dual frequency, dual circular polarization, high isolation Fabry-Perot cavity MIMO antenna according to claim 2, is characterized in that, the dielectric constant of the fourth dielectric plate shown is 4.4, and the thickness is 4mm, the dielectric constant of the fifth dielectric plate is 4.4, and the thickness is 4mm. 9. A dual frequency, dual circular polarization, high isolation Fabry-Perot cavity MIMO antenna processing method, is characterized in that, comprises the following steps: Step 1: Place a partial reflective surface above the feed antenna to form an antenna unit; Step 2: Rotate the antenna units into a MIMO antenna array; Step 3: Add absorbers between units. 10. The method for processing a dual-frequency, dual-circularly polarized, high-isolation Fabry-Perot cavity MIMO antenna according to claim 8, wherein the first dielectric substrate is provided with a plurality of fixing holes The second medium substrate is provided with a plurality of fixing holes corresponding to the openings of the first medium substrate. One end of the nylon medium support column is fixedly arranged in the fixing hole of the first medium plate, and the other end is fixedly arranged in the second medium plate. In the fixing hole of the dielectric board, the second dielectric board is supported to be placed above the slotted metal ground. A part of the reflective surface is placed above the feed antenna, and the two form an antenna unit, and the antenna units are rotated by 90° and arranged to form a 2×2 MIMO antenna. The specific method for placing the wave absorber is as follows: the wave absorber is formed into a cross-shaped array and placed between the four antenna units to fix the feed antenna and part of the reflective surface, and support the part of the reflective surface so that it is placed on the positive side of the feed antenna. above.

Images