A multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate

Abstract

The present invention relates to a multi-frequency, high-gain terahertz microstrip antenna based on a photonic crystal substrate. The purpose of the present invention is to provide a multi-frequency, high-gain terahertz microstrip antenna based on a photonic crystal substrate. The antenna comprises a ground plate, a second dielectric substrate, a first dielectric substrate, and a radiating patch. The ground plate is adhered to the second dielectric substrate, and a photonic crystal structure is disposed in the second dielectric substrate. The first dielectric substrate is bonded to the second dielectric substrate via a prepreg. The radiating patch is etched on the first dielectric substrate and is matched and connected to a quarter-impedance converter and a 50Ω microstrip transmission line. The ends of the quarter-impedance converter are connected to the radiating patch and the 50Ω microstrip transmission line, respectively. Compared with the prior art, the antenna of the present invention meets the requirements for stable operation in three THz frequency bands and has high gain in all three operating frequency bands. It has a simple, novel structure, and is easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of mobile communication technology, and in particular to a multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate. Background Art

[0002] With the rapid development of modern mobile communications, wireless spectrum resources are becoming increasingly scarce, and the probability of interference between wireless signals has increased significantly. Utilizing higher-frequency terahertz (THz) bands for communications will effectively alleviate the increasingly limited spectrum resources and capacity constraints of current wireless systems. Terahertz radiation is electromagnetic radiation with a frequency between microwaves and infrared, ranging from 0.1 to 10 THz. Compared with microwave communications, THz communications offer greater transmission capacity, improved confidentiality, and enhanced anti-interference capabilities. Compared with optical communications, THz communications utilize lower photon energy and better penetration through dust and smoke, ensuring reliable communications even in harsh environments. However, the effective application of THz bands in communications requires the development of related functional components, such as THz antennas and filters.

[0003] Microstrip antennas offer significant advantages in wireless communication systems due to their low profile, small size, simple processing, and ease of integration. However, current single-band microstrip antennas cannot meet the multi-band and high-speed transmission requirements of communication systems, and surface wave loss in the microstrip antenna substrate limits further improvements in antenna gain.

[0004] Photonic crystal substrates have a frequency bandgap characteristic, which constrains electromagnetic waves within the bandgap and prevents them from propagating freely. This effectively reduces the microstrip antenna substrate's absorption of electromagnetic waves, reduces the antenna's surface wave loss, and improves the antenna's gain. However, introducing air-hole photonic crystals into terahertz antenna substrates has not significantly improved antenna gain or enabled multi-band operation. Terahertz microstrip antennas suffer from a single frequency band and degraded antenna performance due to surface wave loss. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art by providing a multi-frequency, high-gain terahertz microstrip antenna based on a photonic crystal substrate. Terahertz microstrip antennas suffer from a single frequency band and degraded performance due to surface wave loss. The present invention proposes a multi-frequency, high-gain terahertz microstrip antenna based on a polyimide rectangular dielectric pillar photonic crystal. By using two dielectric substrates made of different materials, this antenna modifies the electromagnetic resonance of the antenna, enabling multiple resonant frequencies and achieving multi-band operation.

[0006] The applicant also embedded a 5×5 periodically arranged polyimide rectangular dielectric column photonic crystal with a small dielectric constant in the second dielectric substrate layer to suppress surface waves propagating along the second dielectric substrate, increase the electromagnetic wave radiation power of the antenna, reduce the antenna's return loss, and improve the antenna's gain.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The purpose of the present invention is to provide a multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate, the antenna comprising a ground plate, a second dielectric substrate, a first dielectric substrate, and a radiation patch, wherein specifically:

[0009] The ground plate is adhered to the bottom of the second dielectric substrate, and the photonic crystal structure is provided in the second dielectric substrate;

[0010] The first dielectric substrate is bonded to the second dielectric substrate via a prepreg;

[0011] A radiation patch is etched on the first dielectric substrate. The radiation patch is matched and connected with a quarter impedance converter and a 50Ω microstrip transmission line. Two ends of the quarter impedance converter are respectively connected to the radiation patch and the 50Ω microstrip transmission line.

[0012] Furthermore, the second dielectric substrate is a high-resistance silicon substrate with a dielectric constant of 11.9 and a loss tangent value of 0.00025.

[0013] Furthermore, the second dielectric substrate has a length of 260 um, a width of 300 um, and a height of 35 um.

[0014] Furthermore, the first dielectric substrate is a polyimide substrate with a dielectric constant of 3.5 and a loss tangent value of 0.0027.

[0015] Furthermore, the first dielectric substrate and the second dielectric substrate have the same size.

[0016] Furthermore, the photonic crystal structure includes rectangular dielectric columns arranged in a 5×5 periodic pattern.

[0017] Furthermore, the rectangular dielectric column is a polyimide rectangular dielectric column with a dielectric constant of 3.5 and a loss tangent value of 0.0027, and the height of the rectangular dielectric column is the same as that of the second dielectric substrate.

[0018] Furthermore, the radiation patch includes a rectangular patch, two circular patches, a first slit and a second slit;

[0019] The rectangular patch is arranged at the center of the first dielectric substrate, the two circular patches are symmetrically arranged at two right angles to the rectangular patch, and the first slit and the second slit are symmetrically opened in the middle of the rectangular patch.

[0020] Furthermore, the rectangular patch has a length of 120 μm and a width of 115 μm;

[0021] The radius of the circular patch is 30um;

[0022] The first gap and the second gap have the same size, and the two gaps are centrally symmetrically distributed based on the geometric center of the rectangular patch.

[0023] Furthermore, the operating frequency bands of the antenna include: 0.35THz-0.369THz, 0.568THz-0.59THz, and 0.679THz-0.704THz.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) The antenna in this technical solution is loaded with two circular patches on both sides of the upper part of the rectangular radiation patch to increase the radiation area of ​​the antenna and improve the impedance bandwidth of the antenna. Two substrates of different materials are provided to regulate the electromagnetic resonant frequency of the antenna, realizing multi-band operation of the antenna. The frequency bandgap characteristics of the photonic crystal dielectric substrate are utilized to weaken the absorption of electromagnetic waves by the microstrip antenna substrate, reduce the surface wave loss of the antenna, and improve the gain of the antenna.

[0026] 2) The antenna in this technical solution meets the requirements for stable operation in the three THz frequency bands, and has high gain in all three frequency bands. The antenna structure is simple and novel and easy to implement. Overall, the antenna has the characteristics of low loss, high radiation performance, small size, and easy integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural diagram of the multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate provided by this technical solution.

[0028] Figure 2 This is a schematic structural diagram of the second dielectric substrate provided by this technical solution.

[0029] Figure 3 This is a parameter diagram of the return loss S11 of the homogeneous substrate antenna and the multi-frequency high-gain terahertz microstrip antenna (photonic crystal substrate antenna) based on the photonic crystal substrate provided by this technical solution.

[0030] Figure 4Gain parameter diagram of the homogeneous substrate antenna and the multi-frequency high-gain terahertz microstrip antenna (photonic crystal substrate antenna) based on the photonic crystal substrate provided by this technical solution.

[0031] Figure 5 The E-plane and H-plane radiation patterns of the multi-frequency high-gain terahertz microstrip antenna based on the photonic crystal substrate provided by this technical solution at a resonant frequency of 0.36 THz.

[0032] Figure 6 The E-plane and H-plane radiation patterns of the multi-frequency high-gain terahertz microstrip antenna based on the photonic crystal substrate provided by this technical solution at a resonant frequency of 0.58 THz.

[0033] Figure 7 The E-plane and H-plane radiation patterns of the multi-frequency high-gain terahertz microstrip antenna based on the photonic crystal substrate provided by this technical solution at a resonant frequency of 0.692 THz.

[0034] The numbers in the figure show:

[0035] 1. Ground plane, 2. Second dielectric substrate, 3. First dielectric substrate, 4. Radiating patch, 5. Quarter-impedance converter, 6. 50Ω microstrip transmission line, 7. First slot, 8. Second slot, 9. Circular patch, 10. Photonic crystal structure, 11. Rectangular patch. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0037] like Figure 1 and Figure 2 As shown, the structure of a multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate in the present invention includes: a ground plate 1, a second dielectric substrate 2, a first dielectric substrate 3, a radiation patch 4, a quarter impedance converter 5, a 50Ω microstrip transmission line 6, a first slot 7, a second slot 8, a circular patch 9, a photonic crystal structure 10, and a rectangular patch 11.

[0038] The ground plate 1 is a rectangular metal ground plate with a length of 260 μm and a width of 300 μm. The ground plate 1 is adhered to the bottom of a second dielectric substrate 2. The material of the second dielectric substrate 2 is high-resistance silicon with a dielectric constant of 11.9 and a loss tangent of 0.00025. The ground plate 1 has a length of 260 μm, a width of 300 μm, and a height of 35 μm. The second dielectric substrate 2 has an embedded photonic crystal structure 10. The photonic crystal structure 10 includes a 5×5 periodic arrangement of rectangular dielectric columns. The rectangular dielectric columns are made of polyimide with a dielectric constant of 3.5 and a loss tangent of 0.0027. The length of the rectangular dielectric columns is 12.5 μm, the width is 25 μm, and the height is 35 μm.

[0039] The first dielectric substrate 3 is bonded to the top of the second dielectric substrate 2 with a prepreg. The material of the first dielectric substrate 3 is polyimide with a dielectric constant of 3.5 and a loss tangent value of 0.0027. The length is 260 μm, the width is 300 μm, and the height is 15 μm. The radiation patch 4 is etched on the upper surface of the first dielectric substrate 3. The radiation patch 4 includes a rectangular patch 11, two circular patches 9, a first slit 7, and a second slit 8. The rectangular patch 11 is arranged in the center of the upper surface of the first dielectric substrate, and the two circular patches 9 are symmetrically arranged. The first and second slots 7 and 8 are located on both sides of the upper portion of the rectangular patch 11. The rectangular patch 11 in the radiating patch 4 is 120 μm long and 115 μm wide. The circular patch 9 has a radius of 30 μm. The first slot 7 is composed of a rectangle on each side of a semicircular ring, with an inner radius of 9 μm and an outer radius of 12 μm. The rectangle is 12 μm long and 3 μm wide. The first and second slots 7 and 8 are identical in size and shape and are symmetrical with the second slot 8 about the center of the rectangular patch 11. The quarter-impedance transformer 5 and the 50Ω microstrip transmission line 6 are located in the middle of the lower portion of the radiating patch 4. The quarter-impedance transformer 5 is 50 μm long and 10 μm wide, and the 50Ω microstrip transmission line 6 is 20 μm long and 34 μm wide.

[0040] The multi-frequency, high-gain terahertz microstrip antenna based on a photonic crystal substrate in this embodiment is fed via a 50Ω microstrip line and a quarter-impedance transformer, achieving impedance matching between the feed port and the radiating patch. The two circular patches increase the antenna's radiation area and improve its impedance bandwidth. Using two substrates made of different materials regulates the antenna's electromagnetic resonant frequency, enabling it to operate in three frequency bands. Furthermore, the second dielectric substrate incorporates polyimide rectangular dielectric rod photonic crystals, reducing surface wave loss and significantly increasing the antenna's gain. By optimizing various dimensional parameters of the antenna, this embodiment achieves low loss, high radiation performance, compact size, and ease of integration.

[0041] In this embodiment, the radiation parameter performance of the antenna is verified using CST electromagnetic simulation software.

[0042] Figure 3 The return loss S11 parameter diagram of the homogeneous substrate antenna and the multi-frequency high-gain terahertz microstrip antenna (photonic crystal substrate antenna) based on the photonic crystal substrate provided by this technical solution. The return loss is the ratio of the signal reflection power to the input power. When the return loss of the antenna is less than -10dB, it means that the antenna is suitable for the working frequency band. Figure 3 As shown in the figure, from the return loss S11 parameter diagram of the homogeneous substrate antenna and the multi-frequency high-gain terahertz microstrip antenna based on the photonic crystal substrate, it can be seen that the resonant frequency of the photonic crystal substrate antenna is shifted compared with the homogeneous substrate antenna. The photonic crystal substrate antenna has three resonant frequencies, one at a lower frequency, that is, around 0.36THz, and its return loss is below -10dB in the operating frequency band of 0.35THz to 0.369THz, and the lowest return loss can reach -31.4dB; the second resonant frequency is at 0.58THz. The return loss is below -10dB in the operating frequency band of 0.568THz to 0.59THz, and the minimum return loss can reach -19.3dB. There is also an operating frequency band of 0.679THz to 0.704THz at a higher frequency, around 0.692THz, with the return loss below -10dB, and the minimum return loss can reach -64.1dB. Compared with the -17.9dB return loss of the homogeneous substrate antenna at the corresponding resonant frequency, it is significantly improved and reduced by 46.2dB.

[0043] Figure 4 Gain parameter diagram of the homogeneous substrate antenna and the multi-frequency high-gain terahertz microstrip antenna (photonic crystal substrate antenna) based on the photonic crystal substrate provided by this technical solution. Figure 4 As shown, it can be seen that the gain of the antenna loaded with polyimide rectangular dielectric column photonic crystal substrate is significantly improved. The gains of the homogeneous substrate antenna at the resonant frequencies of 0.352THz, 0.566THz and 0.678THz are 5.1dBi, 3.1dBi and 5.84dBi respectively. The gains of the photonic crystal substrate antenna at the resonant frequencies of 0.36THz, 0.58THz and 0.692THz are 6.28dBi, 4.84dBi and 7.66dBi respectively, which are 1.18dBi, 1.74dBi and 1.82dBi higher than those of the homogeneous substrate antenna.

[0044] Figure 5 The E-plane and H-plane radiation patterns of the multi-frequency high-gain terahertz microstrip antenna based on the photonic crystal substrate provided by this technical solution at a resonant frequency of 0.36THz. Figure 5As shown in Figure 1, the E-plane and H-plane radiation patterns of the terahertz microstrip antenna at 0.36 THz show that its gain at 0.36 THz is 6.28 dBi. The E-plane refers to the cross-sectional pattern consisting of the maximum radiation direction and the electric field direction, and the H-plane refers to the cross-sectional pattern consisting of the maximum radiation direction and the magnetic field direction.

[0045] Figure 6 The E-plane and H-plane radiation patterns of the multi-frequency high-gain terahertz microstrip antenna based on the photonic crystal substrate provided by this technical solution at a resonant frequency of 0.58THz. Figure 6 As shown in FIG, from the E-plane and H-plane radiation patterns of the terahertz microstrip antenna at 0.58 THz, it can be seen that its gain at 0.58 THz is 4.84 dBi.

[0046] Figure 7 The E-plane and H-plane radiation patterns of the multi-frequency high-gain terahertz microstrip antenna based on the photonic crystal substrate provided by this technical solution at a resonant frequency of 0.692THz. Figure 7 As shown in FIG, from the E-plane and H-plane radiation patterns of the terahertz microstrip antenna at 0.692 THz, it can be seen that its gain at 0.692 THz is 7.66 dBi.

[0047] The multi-frequency high-gain terahertz microstrip antenna based on the photonic crystal substrate in this embodiment has three operating frequency bands. The operating frequency bands with return loss below -10dB are 0.35THz~0.369THz, 0.568THz~0.59THz and 0.679THz~0.704THz, respectively. The resonant frequencies are 0.36THz, 0.58THz and 0.692THz, respectively. The lowest return loss can reach -31.4dB, -19.3dB and -64.1dB, respectively. It has high gain and low return loss, which can well meet the multi-band working requirements of the antenna in the terahertz band.

[0048] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate, characterized in that: The antenna includes: Ground plate (1); a second dielectric substrate (2) adhered to the ground plane (1), wherein a photonic crystal structure (10) is provided in the second dielectric substrate (2); A first dielectric substrate (3) is bonded to the second dielectric substrate (2) via a prepreg; A radiation patch (4) is etched on the first dielectric substrate (3), wherein the radiation patch (4) is matched and connected with a quarter impedance converter (5) and a 50Ω microstrip transmission line (6), and two ends of the quarter impedance converter (5) are respectively connected to the radiation patch (4) and the 50Ω microstrip transmission line (6); The photonic crystal structure (10) includes rectangular dielectric columns arranged in a 5×5 periodic pattern; The rectangular dielectric column is a polyimide rectangular dielectric column with a dielectric constant of 3.5 and a loss tangent value of 0.0027, and the height of the rectangular dielectric column is the same as that of the second dielectric substrate (2); The radiation patch (4) comprises a rectangular patch (11), two circular patches (9), a first slit (7) and a second slit (8); The rectangular patch is arranged at the center of the first dielectric substrate (3), the two circular patches (9) are symmetrically arranged at two right-angle positions of the rectangular patch (11), and the first slit (7) and the second slit (8) are symmetrically opened at the middle of the rectangular patch (11).

2. The multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate according to claim 1, characterized in that: The second dielectric substrate (2) is a high-resistance silicon substrate with a dielectric constant of 11.9 and a loss tangent value of 0.00025.

3. The multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate according to claim 1, characterized in that: The second dielectric substrate (2) has a length of 260 um, a width of 300 um, and a height of 35 um.

4. The multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate according to claim 1, characterized in that: The first dielectric substrate (3) is a polyimide substrate with a dielectric constant of 3.5 and a loss tangent value of 0.0027.

5. The multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate according to claim 1, characterized in that: The first dielectric substrate (3) and the second dielectric substrate (2) have the same size.

6. The multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate according to claim 1, characterized in that: The rectangular patch (11) has a length of 120 um and a width of 115 um; The radius of the circular patch (9) is 30 um; The first gap (7) and the second gap (8) have the same size, and the two gaps are centrally symmetrically distributed based on the geometric center of the rectangular patch (11).

7. A multi-frequency high-gain terahertz microstrip antenna based on a photonic crystal substrate according to any one of claims 1 to 6, characterized in that: The antenna's operating frequency bands include: 0.35 THz-0.369 THz, 0.568 THz-0.59 THz, and 0.679 THz-0.704 THz.

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