An all-metal circularly polarized frequency scanning antenna based on artificial surface plasmons

Abstract

The present application relates to a kind of full metal circular polarization frequency scanning antennas based on artificial surface plasmons, belong to frequency scanning antenna technical field.The antenna includes three parts of feed waveguide, radiation structure and metal base plate.The radiation structure includes metal ground plate, artificial surface plasmons transmission structure by multiple staggered stepped rectangular wave column body equidistant arrangement, the transmission structure side for realizing TE 10 to TM mode conversion Graduated height transmission structure, and multiple metal cylindrical radiation units periodically arranged.The radiation unit is electromagnetically coupled with transmission structure, excitation space high harmonic wave realizes leaky wave radiation, and generates the orthogonal electric field of phase difference 90 ° and realizes circular polarization.The present application adopts full metal structure, easy to process, resistant to high power, robustness is strong;In 190 GHz-205 GHz frequency band, beam scanning range is-20 ° to +2 °, and main radiation direction axis ratio is less than 3 dB.The present application solves the technical problems that existing leaky wave antenna is difficult to realize circular polarization radiation in terahertz frequency band, structure is complex.

Description

Technical Field

[0001] This invention belongs to the field of microwave antenna technology, specifically relating to an all-metal circularly polarized frequency scanning antenna based on artificial surface plasmon polaritons in the field of frequency scanning antenna technology. Background Technology

[0002] Leaky wave antennas are a type of traveling wave antenna, in which traveling waves propagate and leak through a radiating aperture. They are widely used due to their unique frequency scanning characteristics, as well as advantages such as wide bandwidth, high directivity, narrow beamwidth, and simple feeding structure. Leaky wave radiation is typically achieved by loading periodic or quasi-periodic structures to modulate the electromagnetic energy bound to the transmission line into free space. The characteristics of the transmission line largely determine the radiation characteristics. Therefore, different transmission lines are used in leaky wave antennas, with common types including microstrip lines, integrated substrate waveguides, and gap waveguides.

[0003] Surface plasmon polaritons (SPPs) are mixed excited states formed by the interaction of free electrons and photons that propagate along the metal-dielectric interface, exhibiting highly confined surface wave modes in the dielectric medium outside the metal. Artificial surface plasmon polaritons (SSPPs) are a low-frequency extension of the SPP concept. Simulating the performance of SPPs using artificially designed surfaces with specific structures has significant application value in the design of microwave devices and antennas.

[0004] Traditional SSPP (Surface Plasmon Polarizing) frequency-scanning antennas are primarily designed based on microstrip structures on printed circuit boards. Their low radiation efficiency, low power capacity, and small beam scanning angle limit their development. Considering the terahertz band, microstrip line losses become unacceptable, and metal vias in integrated substrate waveguides are difficult to fabricate above 100 GHz, making it difficult to directly use these traditional technologies in the terahertz band. Surface Plasmon Polarizing (SSPP) waveguides simulate optical SPP characteristics by using corrugated structures in the microwave, millimeter-wave, and terahertz bands. Therefore, SSPP waveguides possess strong field confinement and slow-wave effects, making them applicable to leaky-wave antenna design. Summary of the Invention

[0005] Existing frequency scanning antennas suffer from problems such as narrow beam scanning angle, low radiation efficiency, small power capacity, and difficulty in operating at frequencies of 100 GHz and above. The purpose of this invention is to provide an all-metal circularly polarized frequency scanning antenna based on artificial surface plasmon resonances (ASPRINs). This antenna can operate in the terahertz band as well as lower frequency bands, exhibiting high directivity, wide coverage, and high radiation efficiency. Furthermore, it boasts advantages such as simple design, compact structure, and low cost, making it suitable for applications in modern wireless communication and high-resolution imaging systems.

[0006] To achieve the above objectives, the present invention provides an all-metal circularly polarized frequency scanning antenna based on artificial surface plasmon resonance (ASPRIN), comprising: a feed waveguide (1) for receiving and transmitting externally input electromagnetic waves; a radiation structure (2) disposed at the output end of the feed waveguide (1), comprising a metal ground plane (21), an ASPRIN transmission structure (22) disposed on the metal ground plane (21), a gradually increasing height transmission structure (23) connecting the feed waveguide (1) and the ASPRIN transmission structure (22), and a plurality of radiation elements (24) arranged along the electromagnetic wave propagation direction on one side of the ASPRIN transmission structure (22); and a metal base plate (3) located below the feed waveguide (1) and the radiation structure (2), for supporting and fixing the feed waveguide (1) and the radiation structure (2).

[0007] Furthermore, the feeding waveguide (1) includes a flange (11), a waveguide (12) connected to the flange (11), and an extended waveguide groove (13) formed at the end of the waveguide (12); the extended waveguide groove (13) is connected to the gradient height transmission structure (23) for coupling electromagnetic waves from the waveguide (12) to the radiation structure (2).

[0008] Furthermore, the artificial surface plasmon resonance transport structure (22) is composed of multiple rectangular corrugated columns arranged at equal intervals along the electromagnetic wave propagation direction. Each column has a staggered stepped cross-sectional profile, and a stepped coupling gap is formed between two adjacent columns.

[0009] Furthermore, the gradually increasing height transmission structure (23) is composed of multiple rectangular corrugated columns with the same shape as the columns in the artificial surface plasmon resonance transmission structure (22). The height of each column in the gradually increasing height transmission structure (23) gradually increases along the electromagnetic wave propagation direction to achieve TE in the feed waveguide (1). 10 The conversion of the mode electromagnetic wave into the TM mode electromagnetic wave in the artificial surface plasmon polariton transmission structure (22).

[0010] Furthermore, the radiation unit (24) is a metal cylinder, and multiple radiation units (24) are arranged at equal intervals along the electromagnetic wave propagation direction on the same side of the artificial surface plasmon transmission structure (22).

[0011] Furthermore, the feeding waveguide (1) is provided with pin holes (14) and screw holes (15), and the metal base plate (3) is provided with pin holes (31) corresponding to the pin holes (14) and screw holes (32) corresponding to the screw holes (15). The feeding waveguide (1), the radiating structure (2) and the metal base plate (3) are positioned by pins and fastened together by screws.

[0012] The electromagnetic radiation mechanism of the antenna of this invention is as follows: after the external waveguide is connected to the feed waveguide (1), the electromagnetic wave enters the gradually increasing height transmission structure (23), and its mode is changed by TE. 10 The mode smoothly transitions to the TM mode; subsequently, the TM mode electromagnetic wave is transmitted on the artificial surface plasmon polariton transmission structure (22) and electromagnetically coupled with the radiation unit (24) on one side; the periodically arranged radiation unit (24) introduces disturbances, excites the higher spatial harmonics of the fundamental mode, among which the -1 spatial harmonic is a fast wave in a specific frequency band, satisfies the radiation condition, and generates a pair of orthogonal electric fields with a 90° phase difference, realizing circular polarization radiation; by changing the frequency of the fed electromagnetic wave, the beam direction can be continuously changed. Beneficial effects

[0013] The all-metal circularly polarized frequency scanning antenna based on artificial surface plasmons described in this invention has the following advantages compared with existing frequency scanning leaky-wave antennas: it can operate in the terahertz and Asia-Pacific Hertz bands; it overcomes the open stopband problem, ensuring continuous beam scanning from back to front; it adopts an all-metal structure, which is easy to process, has high power tolerance, and strong robustness; it achieves a wide beam coverage range; and it achieves circularly polarized radiation, with a circularly polarized operating frequency band of 190 GHz-205 GHz, and an antenna axial ratio of less than 3 dB in the main radiation direction within this frequency band. Attached Figure Description

[0014] Figure 1 This is an overall structural diagram of an all-metal circularly polarized frequency scanning antenna based on artificial surface plasmon resonances according to the present invention.

[0015] Figure 2 This is an exploded view (overall structure exploded view) of the present invention.

[0016] Figure 3 This is a structural diagram of the feed waveguide portion of the present invention.

[0017] Figure 4 This is a structural diagram of the radiating structure portion of the present invention.

[0018] Figure 5 This is a top view of the artificial surface plasmon polariton transport structure and radiation unit in the radiation structure part of the present invention.

[0019] Figure 6 This is a side view of the gradually increasing height transmission structure in the radiating structure portion of the present invention.

[0020] Figure 7 This is a structural diagram of the metal base plate of the present invention.

[0021] Figure 8 This is a graph showing the S-parameter test results of the antenna of the present invention (graph showing the S-parameter test results of the present invention).

[0022] Figure 9 This is a radiation gain test pattern of the antenna of the present invention as a function of frequency.

[0023] Figure 10 This is a graph showing the axial ratio test results for the antenna of this invention.

[0024] In the figure: 1-Feed waveguide, 11-Flange, 12-Waveguide, 13-Extended waveguide groove, 14-Pin hole, 15-Screw hole, 2-Radiating structure, 21-Metal floor, 22-Artificial surface plasmon resonance transmission structure, 23-Gradual height transmission structure, 24-Radiating unit, 3-Metal base plate, 31-Pin hole, 32-Screw hole. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0026] This embodiment uses the terahertz frequency band for illustration. The overall assembly diagram of the circularly polarized frequency scanning antenna described in this invention is as follows: Figure 1 As shown, the exploded view is as follows Figure 2 As shown, the antenna adopts an all-metal structure design and is mainly composed of three parts: a feed waveguide (1), a radiating structure in the middle (2), and a metal base plate at the bottom (3).

[0027] like Figure 3 As shown, the feed waveguide (1) serves as the input / output of the antenna and includes a flange (11), a waveguide (12), and an extended waveguide groove (13). The flange (11) is used to connect to an external standard terahertz test device; the extended waveguide groove (13) extends the bottom surface of the waveguide (12) forward in structure, serving as a transition platform to support and dock with the radiation structure (2).

[0028] like Figure 4 As shown, the radiation structure (2) is the core radiation component of this invention. Its bottom is a metal floor (21), and a gradient height transmission structure (23) and an artificial surface plasmon resonance transmission structure (22) are integrally formed on the metal floor (21).

[0029] like Figure 5 As shown, the artificial surface plasmon resonance transmission structure (22) is composed of a series of rectangular corrugated columns arranged at equal intervals along the electromagnetic wave propagation direction. Viewed from above, each column has a staggered, stepped cross-sectional profile, and the stepped gaps between adjacent columns form a good slow-wave transmission line. On one side of the transmission structure (22), multiple metal cylinders are arranged in parallel at equal intervals as radiating units (24), with a predetermined coupling gap between the radiating units (24) and the edge of the transmission structure (22).

[0030] like Figure 6 As shown, to achieve efficient mode switching, the gradient height transmission structure (23) is positioned between the feed waveguide (1) and the artificial surface plasmon resonance transmission structure (22). It is also composed of staggered, stepped pillars, but the height of these pillars gradually increases in a stepped manner along the wave propagation direction. In actual assembly, this gradient height transmission structure (23) is located inside the extended waveguide groove (13) of the feed waveguide (1), thereby reducing the traditional TE transmission in the waveguide. 10 The mode is efficiently converted into a TM mode on an artificial surface plasmon polariton structure.

[0031] like Figure 7 As shown, the metal base plate (3) is a metal block with a certain thickness. During assembly and manufacturing, the feeding waveguide (1), the radiating structure (2) and the metal base plate (3) are first processed into shape by a high-precision CNC machine tool. During assembly, pins are driven into the pin holes (14) on the feeding waveguide (1) and the pin holes (31) on the metal base plate (3) to achieve high-precision alignment and positioning at the micron level. Then, screws are screwed into the screw holes (15, 32) for fastening, thereby ensuring the conductivity continuity of the contact surfaces of each component.

[0032] When the antenna of the present invention is in operation, the bound TM mode electromagnetic energy on the transmission structure (22) is coupled to the radiating element (24). The periodic disturbance formed by the radiating element (24) excites the spatial high-order harmonics, so that the -1 spatial harmonic enters the fast wave region in the target frequency band and radiates into free space. Through the specific staggered step geometry and cylindrical coupling gap, it excites mutually orthogonal electric fields with equal amplitude and 90° phase difference in space, realizing a circularly polarized wave with high purity.

[0033] like Figure 8As shown, the S-parameter test / simulation results of the antenna of the present invention indicate that |S 11 The impedance loss is less than -10 dB in the 190 GHz-205 GHz frequency band, exhibiting excellent impedance matching performance and low return loss. Figure 9 As shown, the antenna's radiation gain pattern verifies its excellent frequency sweep characteristics. During the frequency range of 190 GHz to 205 GHz, the beam pointing achieved a continuous sweep from -20° to +2°, with sidelobe level suppression below -10 dB. Figure 10 The axial ratio (AR) curves shown indicate that within the 190 GHz-205 GHz operating bandwidth, the antenna axial ratio in the main radiation direction is always less than 3 dB, meeting the circular polarization antenna standard.

[0034] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A fully metallic circularly polarized frequency scanning antenna based on artificial surface plasmon resonances, characterized in that, include: Feed waveguide (1) is used to receive and transmit externally input electromagnetic waves; The radiating structure (2), located at the output end of the feed waveguide (1), includes a metal floor (21), an artificial surface plasmon resonance transmission structure (22) located on the metal floor (21), a gradually increasing height transmission structure (23) connecting the feed waveguide (1) and the artificial surface plasmon resonance transmission structure (22), and multiple radiating units (24) arranged along the electromagnetic wave propagation direction on one side of the artificial surface plasmon resonance transmission structure (22); the metal base plate (3), located below the feed waveguide (1) and the radiating structure (2), is used to support and fix the feed waveguide (1) and the radiating structure (2).

2. The antenna according to claim 1, characterized in that, The feeding waveguide (1) includes a flange (11), a waveguide (12) connected to the flange (11), and an extended waveguide groove (13) formed at the end of the waveguide (12); the extended waveguide groove (13) is connected to the gradient height transmission structure (23) for coupling electromagnetic waves from the waveguide (12) to the radiation structure (2).

3. The antenna according to claim 1, characterized in that, The artificial surface plasmon resonance transport structure (22) is composed of multiple rectangular corrugated columns arranged at equal intervals along the electromagnetic wave propagation direction. Each column has a staggered stepped cross-sectional profile, and a stepped coupling gap is formed between two adjacent columns.

4. The antenna according to claim 1, characterized in that, The gradually increasing height transmission structure (23) is composed of multiple rectangular corrugated columns with the same shape as the columns in the artificial surface plasmon resonance transmission structure (22). The height of each column in the gradually increasing height transmission structure (23) gradually increases along the electromagnetic wave propagation direction to realize the TE in the feed waveguide (1). 10 The conversion of the mode electromagnetic wave into the TM mode electromagnetic wave in the artificial surface plasmon polariton transmission structure (22).

5. The antenna according to claim 1, characterized in that, The radiation unit (24) is a metal cylinder, and multiple radiation units (24) are arranged at equal intervals along the electromagnetic wave propagation direction on the same side of the artificial surface plasmon transmission structure (22).

6. The antenna according to claim 1, characterized in that, The feeding waveguide (1) is provided with pin holes (14) and screw holes (15), and the metal base plate (3) is provided with pin holes (31) corresponding to the pin holes (14) and screw holes (32) corresponding to the screw holes (15). The feeding waveguide (1), the radiation structure (2) and the metal base plate (3) are positioned by pins and fastened together by screws.

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