CN112838376B - Broadband High-Gain Fabry-Perot Resonant Cavity Antenna Based on Regular Hexagonal Elements - Google Patents

Abstract

The invention discloses a broadband high-gain Fabry-Perot resonant cavity antenna based on a regular hexagonal unit, which comprises an upper, middle and lower three-layer dielectric substrates (2, 4, 7), and passes through a low dielectric constant nylon frame. (9) Fixed as one. The upper and lower sides of the upper dielectric substrate are respectively an upper reflective surface (1) and a lower reflective surface (3), and the three form a partially reflective surface structure; the lower surface of the intermediate layer dielectric substrate is a parasitic patch (5), both of which form radiation body; the upper surface of the underlying dielectric substrate is a metal floor (6), and the lower surface is a graded microstrip feed line (8), the three form a feed source, and the upper and lower reflective surfaces (1, 3) of this part are periodically arranged. Regular hexagon units, these units are arranged along the perpendicular direction of the three adjacent sides of the regular hexagon; two rectangular slits are engraved on the metal floor to widen the impedance bandwidth. The invention widens the bandwidth of the antenna, improves the gain, and can be used in satellite communication and radar systems.

Description

Broadband High-Gain Fabry-Perot Resonant Cavity Antenna Based on Regular Hexagonal Elements

technical field

The invention belongs to the technical field of antennas, and further relates to a Fabry-Perot resonant cavity antenna, which can be used in satellite communication and radar systems.

Background technique

With the rapid development of modern radar, electronic countermeasures, current and next-generation communication technologies, antennas are one of the important systems of these electronic systems, and their performance requirements are also increasing. Compared with traditional high-gain antennas, Fabry-Perot resonator antennas have obvious advantages in high gain, high efficiency, low profile, simple structure, no need for complex feeding networks, easy fabrication and simple assembly. It has become one of the research hotspots at home and abroad. The Fabry-Perot resonator antenna has a relatively simple quasi-planar structure, and its processing and maintenance difficulty and cost are lower than those of traditional high-gain antennas such as reflectors and waveguide horns. When the same gain is achieved, a higher aperture efficiency And the lower profile height makes it much smaller than such traditional high-gain antennas. Therefore, the Fabry-Perot resonator is usually used to improve the gain performance of the antenna.

Existing Fabry-Perot resonator antennas consist of three parts: a feed, a metal floor, and a partially reflective surface. Due to the existence of an air band gap between the partially reflective surface and the floor, a resonant cavity will be formed, and when the distance between the two meets the value required by the resonance condition, a part of the electromagnetic waves radiated from the feed antenna will be transmitted through the partially reflective surface. , the other part continues to be reflected in the resonant cavity, and the electromagnetic waves after multiple reflections will be superimposed in the same phase on the outer surface of the partial reflection surface, thereby improving the gain of the feed antenna. However, since the Fabry-Perot resonant cavity antenna is still a resonant cavity structure, its 3dB gain bandwidth and impedance bandwidth are relatively narrow, so how to widen its bandwidth is also a challenge to the designer.

In order to solve the above-mentioned problem of narrow gain bandwidth, researchers have proposed many solutions. For example, the paper "Directive Wideband Cavity" published by M.A.Meriche, H.Attia, A.Messai, S.S.I.Mitu and T.A.Denidni in IEEE Antennas and Wireless Propagation Letters, vol.18, no.9, pp.1771-1774, Sept.2019 In Antenna With Single-Layer Meta-Superstrate", a broadband high-gain Fabry-Perot resonator antenna operating in the 12-15GHz frequency band is proposed. The feed source is a slot antenna, and square patches and square rings are etched on both sides of the dielectric substrate as part of the reflection surface to generate a phase gradient with a positive slope and improve the gain bandwidth of the antenna. However, this Fabry-Perot resonator antenna using square elements and slot feeds still has a narrow 3dB gain bandwidth. Experiments show that only 18.7% of the antenna can achieve a 3dB gain bandwidth in the operating frequency range, and The peak gain is 13.78dBi. So if you want to further increase the 3dB gain bandwidth of the antenna, you need to make further improvements to the feed structure and part of the reflective surface.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a broadband high-gain Fabry-Perot resonant cavity antenna based on regular hexagonal elements to improve the gain bandwidth of the Fabry-Perot resonant cavity antenna in view of the above-mentioned deficiencies of the prior art.

In order to achieve the above object, the technical scheme adopted by the present invention is as follows:

1. A broadband high-gain Fabry-Perot resonant cavity antenna based on a regular hexagonal unit, comprising an upper dielectric substrate 2, an intermediate dielectric substrate 4, a bottom dielectric substrate 7 and a support 9, the three substrates are from the bottom The upper part is fixed as a whole by the support 9; the upper surface of the upper dielectric substrate 2 is a partial upper reflective surface 1, and the lower part is a part of the lower reflective surface 3, and the three form a partially reflective surface structure; the lower surface of the intermediate layer dielectric substrate 4 is The parasitic patch 5, the two form a radiator structure; the upper surface of the underlying dielectric substrate 7 is a metal floor 6, and the lower surface is a graded microstrip feed line 8, and the three form a feed structure, which is characterized in that:

The part of the upper reflective surface 1 and the part of the lower reflective surface 3 all use regularly arranged regular hexagonal units, and these units are arranged along the direction of the mid-perpendicular line of the three adjacent sides of the regular hexagon;

The support 9 adopts a low dielectric constant nylon frame to form a Fabry-Perot resonant cavity between the partial lower reflective surface 3 and the metal floor 6, and between the parasitic patch 5 and the metal floor 6 Air band gap to suppress antenna surface wave excitation;

The metal floor 6 is etched with two rectangular slits 61 and 62 to widen the impedance bandwidth of the antenna.

Preferably, the regular hexagonal unit of the reflective surface 1 on the part is a regular hexagonal patch;

Preferably, the regular hexagonal unit of the part of the lower reflective surface 3 is a combination of regular hexagonal apertures and hexapod branches in the aperture;

Preferably, the arrangement period P of the regular hexagonal units on the upper and lower reflective surfaces is 6mm-9mm.

Preferably, the length L1 of the regular hexagonal patch unit in the partial upper reflective surface 1 is 5mm-7mm;

Preferably, the outer diameter side length L2 of the regular hexagonal aperture in the partial lower reflective surface 3 is 5mm-7mm, the inner diameter and side length L3 of the regular hexagonal aperture are 4mm-6mm, and the side length L4 of the hexagonal branch is 5mm-7mm , the width W of the six-legged branch is 0.5mm-3.5mm.

Preferably, the support 9 includes a square outer frame 91 and a square inner frame 92. The outer frame is divided into upper and lower layers 911 and 912, which are fixed by four support columns 93, and the lower frame 912 has only three sides, a square The inner frame 92 is fixed in the middle of the lower frame 912 , the upper dielectric substrate 2 is fixed in the upper frame 911 of the outer frame by inlaying, and the bottom dielectric substrate 7 is inserted into the lower layer 912 of the outer frame through two notches on the support column 93 , the interlayer dielectric substrate 4 is fixed in the square inner frame 92 by inlaying.

Preferably, the upper and lower layers 911 and 912 of the square outer frame are separated by support columns 93 to form a Fabry-Perot resonant cavity, and the resonant cavity height H is 10mm-30mm. An air band gap exists between the lower layers 912, and the band gap height H0 is 1 mm-5 mm.

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

First, in the present invention, for the first time in the same type of broadband high-gain Fabry-Perot resonant cavity antennas, periodically arranged regular hexagonal units are used, and the units are along the direction of the mid-perpendicular line of three adjacent sides of the regular hexagon. Compared with the traditional square unit and circular unit, there is one more arrangement direction, so the arrangement between the units is more compact, the coupling is stronger, and it obtains a positive phase gradient in a wider frequency range;

Second, the present invention avoids the contact between the parasitic patch and the feeder due to the use of the dual-slot coupling patch feeding method. Therefore, the surface wave excitation can be well suppressed, which is beneficial to improve the impedance bandwidth of the antenna and improve the radiation pattern of the antenna;

Third, because the present invention adopts a low dielectric constant nylon frame, compared with the traditional nylon column, it does not need to punch holes on the dielectric substrate, so the integrity of the antenna is protected, which not only stabilizes the performance of the antenna, but also improves the performance of the antenna. the practical usability of the antenna;

Description of drawings

1 is a schematic diagram of the overall structure of an embodiment of the present invention;

Fig. 2 is the layered structure schematic diagram of Fig. 1;

3 is a schematic diagram of the low dielectric constant nylon frame in FIG. 1;

FIG. 4 is a schematic diagram of the structure of the partial upper reflective surface in FIG. 2;

Fig. 5 is the partial lower reflective surface structure schematic diagram in Fig. 2;

6 is a schematic structural diagram of the parasitic patch in FIG. 2;

Fig. 7 is the structural schematic diagram of the metal floor and the gap on the metal floor in Fig. 2;

FIG. 8 is a schematic structural diagram of the gradient feeder in FIG. 2;

9 is a schematic diagram of a feed structure of a Fabry-Perot resonator in an embodiment of the present invention;

FIG. 10 is a schematic diagram of the height between the dielectric substrates of each layer in an embodiment of the present invention;

FIG. 11 is a return loss characteristic curve diagram in an embodiment of the present invention;

FIG. 12 is a radiation pattern on the xoz plane and the yoz plane in the embodiment of the present invention.

Detailed ways

The specific embodiments and effects of the present invention will be described in further detail below with reference to the accompanying drawings.

Referring to Figure 1, Figure 2 and Figure 3: the broadband high-gain Fabry-Perot resonant cavity antenna of this example includes a part of an upper reflective surface 1, an upper dielectric substrate 2, a part of a lower reflective surface 3, an intermediate dielectric substrate 4, Parasitic patch 5, metal floor 6, underlying dielectric substrate 7, microstrip feeder 8, support 9, wherein:

The support member 9 includes a square outer frame 91 and a square inner frame 92. The outer frame is divided into an upper layer 911 and a lower layer 912, and the two layers are fixed by four supporting columns 93 with a height of H, and the lower frame 912 has only With three sides, the square inner frame 92 is fixed in the middle of the lower frame 912 , and its size is one third of the large frame, and the lower ends of the first two support columns of the four support columns 93 are provided with notches.

The part of the upper reflection surface 1 and the part of the lower reflection surface 3 are located at the upper part and the lower part of the upper dielectric substrate 2, respectively, and the three form a part of the reflection surface structure. The reflection surface structure is fixed in the upper frame 911 of the outer frame by inlaying, Used to increase the gain of Fabry-Perot resonator antennas.

The parasitic patch 5 is located on the lower surface of the intermediate layer dielectric substrate 4, and the two form a radiator structure. The radiator structure is fixed in the square inner frame 92 by inlaying, and is used for a Fabry-Perot resonant cavity. Antennas provide relatively smooth radiation.

The metal floor 6 and the graded microstrip feed line 8 are respectively located on the upper surface and the lower surface of the underlying dielectric substrate 7, and the three form a feed structure, which is inserted into the outer frame through two notches on the support column 93 In the lower layer 912 of the outer frame, an air band gap exists between the radiator structure in the inner frame 92 and the feed structure in the lower layer 912 of the outer frame, so as to suppress the surface wave excitation of the feed antenna. The feed structure and the radiator structure form a feed antenna.

The upper dielectric substrate 2 and the bottom dielectric substrate 7 have the same size, the side length L is 60mm-80mm, the height H1 is 0.8mm-1.2mm, the side length L6 of the middle layer dielectric substrate is 15mm-20mm, and the height H3 is 0.8 mm-1.2mm, the side length L of the metal floor 6 is 60mm-80mm. Further, the dielectric constants of the upper dielectric substrate 2 and the underlying dielectric substrate 4 are ε ₁ . In this example, but not limited to, L is 72mm, H1 is 1mm, L6 is 18mm, H3 is 0.8mm, and ε ₁ is 3.4. The thickness H2 of the underlying dielectric substrate 7 is 0.7 mm-1 mm.

4, the part of the upper reflective surface 1 is formed by periodic arrangement of regular hexagonal patches, and its arrangement direction is the direction of the perpendicular line of the three adjacent sides of the regular hexagon. The form of the mechanism surrounded by six identical patches can greatly enhance the coupling between the regular hexagonal patches, so that the regular hexagonal unit can obtain a positive phase gradient in a wide operating frequency range, and its arrangement period P is 7mm-9mm, in this example, but not limited to, P is 8mm, and the side length L1 of each regular hexagonal patch is 5mm-7mm, in this example, but not limited to, L1 is 6mm.

Referring to Fig. 5: the part of the lower reflective surface 3 is formed by periodic arrangement of regular hexagonal cells, which are composed of regular hexagonal apertures and hexapod branches in the aperture, and the arrangement direction is the three adjacent sides of the regular hexagon. In the direction of the vertical line, the function of the regular hexagonal aperture is to enhance the coupling between regular hexagonal units and improve the reflection performance of some reflective surfaces, and the function of the hexagonal branch is to extend the current flow path to reduce the regular hexagonal unit. The size of the antenna makes the antenna more miniaturized. These units are printed on the lower surface of the upper dielectric substrate 2. The outer diameter and side length of the regular hexagonal aperture is 5mm-7mm, and the inner diameter and side length L3 of the regular hexagonal aperture is 4mm-6mm. , the side length L4 of the hexapod branch is 5mm-7mm, and the width W of the hexapod branch is 0.5mm-3.5mm. In this example, L2 is 6mm, L3 is 5mm, L4 is 6mm, and W is 0.5mm. The period P is the same as the arrangement period of the partially upper reflective surface 1 .

Referring to Figure 6: The parasitic patch 5 is printed on the lower surface of the intermediate layer dielectric substrate 4. As the main radiating element in the Fabry-Perot resonant cavity antenna, its performance directly affects the entire Fabry-Perot cavity antenna. To determine the performance of the resonant cavity antenna, the shape of the patch is square, its side length L5 is 7mm-10mm, and the distance D0 from the parasitic patch 5 to the edge of the intermediate layer dielectric substrate 4 is 4.5mm-6.5mm. But not limited to 8mm for L5 and 5.5mm for D0.

7, the metal floor 6 is printed on the upper surface of the underlying dielectric substrate 7, and two rectangular slits 61 and 62 are etched in the middle position. The coupling between these two slits can enable the feed antenna to operate within the frequency range. A new resonance point is generated, and the appearance of the resonance point can widen the working bandwidth of the Fabry-Perot resonator antenna and provide broadband conditions for the Fabry resonator antenna. Among them, the long side of the first rectangular slot 61 SL1 is 7mm-9mm, and the short side SW1 is 1mm-3mm; the long side SL2 of the second rectangular slit 62 is 5mm-7mm, and the short side SW2 is 0.5mm-1.5mm; the distance D2 between the rectangular slit 61 and one side of the metal floor 6 is 33mm-37mm, the distance D3 between the rectangular gap 62 and the other side of the metal floor 6 is 34mm-38mm, and the distance D1 between the rectangular gaps is 0.5mm-1.5mm. In this example, SL1 is 8mm, SW1 is 2mm, SL2 is 6mm, SW2 is 1mm, D2 is 35mm, D3 is 35mm, and D1 is 1mm.

Referring to Figure 8: the gradient microstrip feeder 8 is printed on the lower surface of the underlying dielectric substrate 7, which is perpendicular to the two rectangular slits 61 and 62 on the upper surface of the underlying dielectric substrate. The microstrip feeder has two main functions: One is responsible for transmitting radio frequency signals, and the other is responsible for adjusting the impedance matching of the Fabry-Perot resonant cavity antenna. Only when the impedance of the feeding unit of the antenna is matched, the radiation performance and radiation efficiency of the antenna will be improved. The microstrip feeder is composed of a small impedance microstrip line 81 and a large impedance microstrip line 82, wherein the width W1 of the small impedance microstrip line 81 is 1mm-1.4mm, and the length L7 is 11.5mm-13.5mm; the large impedance microstrip line The width W2 of 81 is 1.5mm-3.5mm, and the length L8 is 24mm-28mm. In this example, but not limited to, W1 is 1.2mm, L7 is 12.3mm, W2 is 1.5mm, and L8 is 26.5mm.

Referring to FIG. 9 : a feed antenna composed of a radiator structure and a feed structure, which is one of the main components of the Fabry-Perot cavity antenna, mainly provides electromagnetic wave radiation for the Fabry-Perot cavity.

Referring to FIG. 10 : the height H3 between the upper dielectric substrate 2 and the bottom dielectric substrate 7 is 15mm-17mm, and the height H4 between the intermediate layer dielectric substrate 4 and the bottom dielectric substrate 7 is 1.3mm-3.3mm. Limited to 16mm for H3 and 2.3mm for H4. The height H3 is the height of the antenna resonant cavity, and the height H4 is the height of the air band gap. These two heights have obvious effects on the antenna performance. The height of the antenna resonant cavity has a more obvious effect on the gain performance of the antenna. The height of the antenna has a significant impact on the impedance matching performance of the antenna, so only by adjusting the heights of the two reasonably can the performance of the antenna be optimal.

The effect of the present invention can be further described in combination with the simulation results:

1. Simulation content:

Simulation 1, using the commercial simulation software HFSS_15.0 to simulate and calculate the return loss parameter and gain of the embodiment of the present invention, and the result is shown in FIG. 11 .

It can be seen from Fig. 11 that, taking the reflection coefficient≤-10dB as the standard, the working bandwidth of the feed antenna in this embodiment is 8.8GHz:11.4GHz, and its relative bandwidth is 25.7%, and the working bandwidth of the Fabry-Perot resonant cavity antenna is 8.4GHz:11.3GHz, its relative bandwidth is 29.4%; the highest gain of the feed antenna is 7dBi, the highest gain of the Fabry-Perot cavity antenna is 14dBi, and the maximum gain of the Fabry-Perot cavity antenna is 3dB The gain bandwidth is 8.4GHz:11.2GHz, the relative bandwidth is 28%, and the center frequency of the feed antenna and the Fabry-Perot cavity antenna are both 10GHz.

In simulation 2, the commercial simulation software HFSS_15.0 is used to simulate and calculate the far-field radiation pattern of the embodiment of the present invention, and the result is shown in Figure 12, wherein:

Fig. 12(a) is the radiation pattern of the E-plane and H-plane of the embodiment antenna at 8.4 GHz;

Fig. 12(b) is the radiation pattern of the E-plane and H-plane of the embodiment antenna at 9GHz;

Fig. 12(c) is the radiation pattern of the E-plane and the H-plane of the embodiment antenna at 11.2 GHz.

It can be seen from Fig. 12(a) that when the antenna of the embodiment of the present invention operates at 8.4 GHz, the maximum radiation directions of the radiation patterns of the E-plane and H-plane are at 0 degrees, and the side lobe level is lower than -11 dB.

It can be seen from Fig. 12(b) that when the antenna of the embodiment of the present invention works at 9 GHz, the maximum radiation direction of the radiation pattern of the E-plane and H-plane is at 0 degrees, and the side lobe level is lower than -15dB, and it is at this frequency. The pattern of the points is more symmetrical about the 0-degree line.

It can be seen from Fig. 12(c) that when the antenna of the embodiment of the present invention works at 11.2 GHz, the maximum radiation directions of the radiation patterns of the E-plane and H-plane are at 0 degrees, and the side lobe level is lower than -13dB.

The above simulation results show that when the antenna of the present invention uses the partial reflective surface of the regular hexagonal unit, the working bandwidth and the 3dB gain bandwidth are greatly broadened, and the gain in the maximum radiation direction is also significantly improved, and it has a good Radiation pattern.

Claims (8)

1. A broadband high-gain Fabry-Perot resonant cavity antenna based on a regular hexagon unit comprises an upper-layer dielectric substrate (2), an intermediate-layer dielectric substrate (4), a bottom-layer dielectric substrate (7) and a support piece (9), wherein the three substrates are fixed into a whole from bottom to top through the support piece (9); the upper surface of the upper layer medium substrate (2) is a partial upper reflecting surface (1), the lower part is a partial lower reflecting surface (3), and the three form a partial reflecting surface structure; the lower surface of the middle layer dielectric substrate (4) is provided with a parasitic patch (5), and the parasitic patch form a radiator structure; the upper surface of this bottom dielectric substrate (7) is metal floor (6), and the lower surface is gradual change type microstrip feeder (8), and the three forms feed structure, its characterized in that:

the partial upper reflecting surface (1) and the partial lower reflecting surface (3) are periodically arranged regular hexagon units which are arranged along the perpendicular bisector direction of three adjacent sides of the regular hexagon;

regular hexagonal cells of the partial upper reflective surface (1), which are regular hexagonal patches;

regular hexagonal cells of the partial lower reflective surface (3) being a combination of a regular hexagonal aperture and a six-legged branch within the aperture;

the arrangement period P of the regular hexagon units on the upper and lower reflecting surfaces is 6-9 mm;

the support (9) adopts a low dielectric constant nylon frame to form a Fabry-Perot resonant cavity between the partial lower reflecting surface (3) and the metal floor (6), and an air band gap is formed between the parasitic patch (5) and the metal floor (6) to inhibit the excitation of the antenna surface wave;

the metal floor (6) is etched with a first rectangular slot (61) and a second rectangular slot (62) to widen the impedance bandwidth of the antenna.

2. The antenna of claim 1, wherein:

the length L1 of the regular hexagon patch cells in the partial upper reflecting surface (1) is 5mm-7 mm;

the length of the side L2 of the outer diameter of the regular hexagon aperture in the partial lower reflecting surface (3) is 5mm-7mm, the length of the side L3 of the inner diameter of the regular hexagon aperture is 4mm-6mm, the length of the side L4 of the six-foot branch is 5mm-7mm, and the width W of the six-foot branch is 0.5mm-3.5 mm.

3. The antenna according to claim 1, characterized in that the support member (9) comprises a square outer frame (91) and a square inner frame (92), the outer frame is divided into an upper layer and a lower layer, the outer frame is fixed by four supporting columns (93), the lower layer frame (912) has only three sides, the square inner frame (92) is fixed in the middle of the lower layer frame (912), the upper layer dielectric substrate (2) is fixed in the upper layer frame (911) of the outer frame in an embedding manner, the lower layer dielectric substrate (7) is inserted into the lower layer frame (912) through two notches in the supporting columns (93), and the middle layer dielectric substrate (4) is fixed in the square inner frame (92) in an embedding manner.

4. An antenna according to claim 3, wherein the upper and lower layers of the square outer frame are separated by a support post (93) to form a Fabry-Perot cavity with a height H of 10mm-30mm, and an air gap exists between the square inner frame (92) and the square lower frame (912), and the gap height H0 is 1mm-5 mm.

5. The antenna of claim 1, wherein the upper dielectric substrate (2) and the bottom dielectric substrate (7) are square dielectric substrates, and the side length and the dielectric constant of the upper dielectric substrate and the bottom dielectric substrate are completely the same, the side length L is 60mm-80mm, and the dielectric constant epsilon is₁3.4, the thickness H1 of the upper dielectric substrate (2) is 0.8mm-1.2mm, and the thickness H2 of the bottom dielectric substrate (7) is 0.7mm-1 mm.

6. An antenna according to claim 5, characterized in that the intermediate layer dielectric substrate (4) is square in shape with a side length L6 less than L, the thickness H3 of the intermediate layer dielectric substrate (4) is 0.8mm-1.2mm, and the dielectric constant ε₂Is 2.2.

7. The antenna of claim 1, wherein the first rectangular slot (61) has a long side SL1 of 7mm-9mm and a short side SW1 of 1mm-3 mm; the long side SL2 of the second rectangular gap (62) is 5mm-7mm, the short side SW2 is 0.5mm-1.5mm, the distance D1 between the rectangular gaps is 0.5mm-1.5mm, the distance D2 between the first rectangular gap (61) and one side of the metal floor (6) is 33mm-37mm, and the distance D3 between the second rectangular gap (62) and the other side of the metal floor (6) is 34mm-38 mm.

8. The antenna according to claim 1, characterized in that the graded microstrip feed line (8) is composed of a small impedance microstrip line (81) and a large impedance microstrip line (82), the small impedance microstrip line (81) having a width W1 of 0.5mm-1.5mm and a length L7 of 11mm-14mm, the large impedance microstrip line (82) having a width W2 of 1mm-3mm and a length L8 of 25mm-27 mm.

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