阅读说明：本技术 基于单面加载pin二极管的宽带可重构频率选择表面 (Broadband reconfigurable frequency selection surface based on single-side loaded PIN diode ) 是由 宗志园 曹海若 鄢亚美 吴文 钱嵩松 司马博羽 王翔 于 2021-07-04 设计创作，主要内容包括：本发明公开了一种基于单面加载PIN二极管的宽带可重构频率选择表面,包括介质板以及介质板上下表面的金属单元；其中介质板上表面的第一金属单元是双方形缝隙环结构,最外层的方形环金属贴片的每条边由中间断开并通过PIN二极管连接,介质板下表面的第二金属单元是在方形金属贴片的每条边蚀刻一个矩形凹槽。本发明在不同极化方式以及不同入射角度下的透射、反射带宽在-2dB均可以达到4GHz,具有双极化、宽频带并且对入射角度不敏感的优点,可用于雷达、超宽带天线等领域。(The invention discloses a broadband reconfigurable frequency selection surface based on a single-side loaded PIN diode, which comprises a dielectric plate and metal units on the upper surface and the lower surface of the dielectric plate; the first metal unit on the upper surface of the dielectric plate is a double square slit ring structure, each edge of the square ring metal patch on the outermost layer is disconnected from the middle and connected through a PIN diode, and the second metal unit on the lower surface of the dielectric plate is formed by etching a rectangular groove on each edge of the square metal patch. The transmission and reflection bandwidths of the invention can reach 4GHz at-2 dB under different polarization modes and different incidence angles, and the invention has the advantages of dual polarization, wide frequency band and insensitivity to the incidence angle and can be used in the fields of radars, ultra-wideband antennas and the like.)

1. A broadband reconfigurable frequency selection surface based on a single-side loaded PIN diode comprises a dielectric slab, and is characterized in that a first metal unit and a second metal unit are respectively arranged on the upper surface and the lower surface of the dielectric slab; the first metal unit comprises a first square ring metal patch with the peripheral side length equal to the unit period size, a second square ring metal patch positioned on the inner side of the first square ring metal patch, and a first square ring metal patch positioned on the inner side of the second square ring metal patch, wherein each side of the first square ring metal patch on the outermost layer is disconnected from the middle and connected through a PIN diode; the second metal unit is a metal patch structure, and rectangular grooves are etched on each edge of the second square metal patch.

2. The broadband reconfigurable frequency selective surface based on the single-sided loaded PIN diode according to claim 1, wherein the PIN diodes on two parallel metal sides of the first square-shaped ring metal patch are in the same direction.

3. The broadband reconfigurable frequency selective surface based on the single-sided loaded PIN diode of claim 1, wherein the side length of the second square metal patch without the etched rectangular groove is less than the unit period size.

4. The broadband reconfigurable frequency selective surface based on the single-sided loaded PIN diode according to claim 3, wherein a rectangular groove etched in the second square metal patch is located in the middle of each side, and the width of the rectangular groove is less than half of the side length of the second square metal patch.

5. The wideband reconfigurable frequency selective surface based on a single-sided loaded PIN diode of claim 1, wherein the side length of the first square-shaped metal patch is smaller than the inner side length of the second square-ring metal patch.

6. The wideband reconfigurable frequency selective surface based on single-sided loaded PIN diodes as claimed in claim 5, wherein the outer edge length of the second square ring metal patch is less than the inner edge length of the first square ring metal patch.

7. The wideband reconfigurable frequency selective surface based on single-sided loaded PIN diodes as claimed in claim 6, wherein the width of the second square ring metal patch is greater than the width of the first square ring metal patch.

8. The wideband reconfigurable frequency selective surface based on single-sided loaded PIN diodes according to claim 5, wherein the first metal elements are symmetrical along a centerline axis.

9. The broadband reconfigurable frequency selection surface based on the single-sided loaded PIN diode according to claim 5, wherein four rectangular grooves etched on the second metal unit are distributed in a manner of being symmetrical up and down, left and right.

10. The single-sided loaded PIN diode based broadband reconfigurable frequency selective surface according to claim 1, wherein the dielectric constant of the dielectric slab is 2.2.

Technical Field

The invention belongs to the field of frequency selection surface design in a periodic structure, and particularly relates to a broadband reconfigurable frequency selection surface based on a single-side loaded PIN diode.

Background

The frequency selective surface is a two-dimensional periodic plane structure which can be used for spatial filtering and has selective filtering characteristics on electromagnetic waves with different working frequencies, incidence angles and polarization states. By adjusting certain parameters, band-pass or band-stop of the FSS in the working frequency band can be realized. After the unit structure is determined, the electromagnetic characteristics of the passive frequency selective surface are basically fixed, and the passive frequency selective surface cannot adapt to a changeable electromagnetic environment. Therefore, a Reconfigurable Frequency Selective Surface (RFSS) arises.

The reconfigurable frequency selective surface is mainly realized by the following methods: 1. the FSS structure is loaded with source devices (e.g., PIN diodes, varactors). 2. A medium with variable electromagnetic properties is used as an FSS substrate (e.g., ferrite substrate, photosensitive organic material, etc.). 3. By changing the coupling between the layers, the resonance characteristics of the frequency selective surface can be changed by controlling the coupling mode and the coupling strength between different layers for the multilayer frequency selective surface. The PIN diode is used as a microwave radio frequency switch, has the advantages of high response speed, small volume, low price and the like, and is a relatively common mode for realizing the repeatable FSS. Based on the reconfigurable frequency selective surface of the PIN diode, the resonant state of the cell can be changed by changing the state of the diode. The loading mode of the diode is divided into a single-sided loading mode and a double-sided loading mode, and the double-sided loading mode is easy to realize dual polarization in performance but has certain difficulty in processing; the single-sided loading mode is easy to process, but the dual-polarized broadband is difficult to realize in performance. In addition, since the electronic control devices all require an applied bias voltage, it is often necessary to add a feed line within the frequency selective surface array. However, the extra feed line greatly affects the electromagnetic properties of the active frequency selective surface (such as frequency shift, increased insertion loss, spurious signal response, etc.), and increases the manufacturing difficulty. By reasonably designing the active frequency selection surface topological structure and taking the metal periodic structure as a feeder line, redundant feeder lines in the active frequency selection surface array can be removed, and the negative influence brought by a feed system is greatly reduced.

Nanjing aerospace university 'a parallel feed type multifunctional active frequency selective surface' (publication number: CN106785467A) proposes a parallel feed type active frequency selective surface. The active frequency selective surface comprises a medium substrate and metal periodic arrays orthogonally arranged on two sides of the medium substrate, wherein the metal periodic arrays comprise a plurality of metal units which are periodically arranged. The metal unit is the square, contains two metal thin line structures, two metal T type structures and diode, and wherein, two metal thin line structure parallel arrangement, the horizontal limit parallel arrangement of two metal T type structures, erect the limit and link into a straight line through the diode. In the metal periodic array, the direction of the diodes in the adjacent metal units in the same row is opposite, and the direction of the diodes in the metal units in the same column is the same. The metal periodic array on one side of the medium loads the varactor, and the metal periodic array on the other side loads the PIN diode. The electromagnetic switch function under TE polarization is realized by controlling the on-off of the PIN diode at the lower layer, and the isolation degree of the active frequency selection surface is more than 24dB at the position of 3GHz in two states of band-pass and band-stop. Although the feed line is simple, the active frequency selection surface has narrow transmission bandwidth and large insertion loss in a pass band when realizing the electromagnetic switch function, does not mention the problem of incident angle, and can not realize dual polarization.

In the patent of 'a C-band active artificial electromagnetic surface' (publication number: 108365343A) of southeast university, a C-band active artificial electromagnetic surface is provided, which consists of a slot type artificial electromagnetic surface, an active element and a feed network, wherein the active element is formed by connecting a PIN diode and a high-frequency constant capacitor in series. The gap type artificial electromagnetic surface comprises a square ring gap structure processed on the upper surface of the dielectric substrate and a metal through hole in the dielectric substrate. The metal through holes are connected with the direct current feeder lines on the back of the dielectric substrate, and all the feeder lines form a feeder network. The feed network on the lower surface of the dielectric substrate is divided into a positive part and a negative part which are respectively connected with the negative electrode and the positive electrode of the PIN diode, and the working state is changed by applying bias voltage to the PIN diode, so that the two states of 'on' and 'off' on the artificial electromagnetic surface are realized. The center frequency of the device is 5.10GHz, the insertion loss is less than 1dB bandwidth in an on state and is 1.32GHz, and the isolation is more than 20dB bandwidth in an off state and is 0.85 GHz. The bandwidth of the artificial electromagnetic surface switching is narrow, and the problems of dual polarization and angle are not considered.

Therefore, the single-side loading of the PIN diode and the realization of the dual-polarized and wide-bandwidth reconfigurable frequency selection surface still have great challenges.

Disclosure of Invention

The invention aims to provide a broadband reconfigurable frequency selection surface based on a single-side loaded PIN diode, which can realize the switching of transmission and reflection functions in an X wave band and has the advantages of simple feeder line, wide-angle incidence and insensitivity to polarization mode.

The technical solution for realizing the purpose of the invention is as follows: a broadband reconfigurable frequency selection surface based on a single-side loaded PIN diode comprises a dielectric slab, wherein a first metal unit and a second metal unit are respectively arranged on the upper surface and the lower surface of the dielectric slab; the first metal unit comprises a first square ring metal patch with the peripheral side length equal to the unit period size, a second square ring metal patch positioned on the inner side of the first square ring metal patch, and a first square ring metal patch positioned on the inner side of the second square ring metal patch, wherein each side of the first square ring metal patch on the outermost layer is disconnected from the middle and connected through a PIN diode; the second metal unit is a metal patch structure, and rectangular grooves are etched on each edge of the second square metal patch.

Furthermore, the direction of the diodes on the two parallel metal edges is consistent.

Further, the side length f of the second square metal patch without etching the rectangular groove is smaller than the unit period size.

Furthermore, the rectangular groove etched on the second square metal patch is located in the middle of each side, and the width of the rectangular groove is smaller than half of the side length of the second square metal patch.

Furthermore, the side length of the first square metal patch is smaller than the inner side length of the second square ring metal patch.

Further, the outer edge length of the second square-ring metal patch is smaller than the inner edge length of the first square-ring metal patch.

Further, the width of the second square-ring metal patch is larger than that of the first square-ring metal patch.

Further, the first metal unit is axisymmetric along the center line.

Furthermore, four rectangular grooves etched in the second metal unit are distributed symmetrically up and down, left and right.

Further, the dielectric constant of the dielectric plate is 2.2.

Compared with the prior art, the invention has the following remarkable advantages: (1) the PIN tubes are all arranged on the upper surface of the dielectric slab, so that only single-side feeding is needed, and the processing is convenient; (2) the reconfigurable FSS array takes the metal structure as a feed network, so that redundant feed lines in the array are effectively reduced, and the negative influence of a feed system on the electromagnetic characteristics of the array is reduced; (3) the oblique incidence angle of the TE/TM polarized wave is in the range of 0-45 degrees, the-2 dB bandwidth in the transmission and reflection states can reach 4GHz, and the broadband dual-polarization non-sensitive to the oblique incidence angle.

The invention is described in further detail below with reference to the figures and the detailed description.

Drawings

FIG. 1 is a schematic diagram of a reconfigurable FSS upper surface periodic structure unit.

FIG. 2 is a hierarchical schematic of the overall architecture of a reconfigurable FSS.

FIG. 3 is a schematic diagram of a reconfigurable FSS upper surface periodic structure unit.

FIG. 4 is a schematic diagram of a reconfigurable FSS lower surface periodic structure unit.

Fig. 5 is a diagram of S11 when the PIN is cut off and TE polarized waves are incident at different angles.

FIG. 6 is a diagram of S11 when the PIN is cut off and the TM polarized wave is incident at different angles.

Fig. 7 is a diagram of S21 when the PIN tube is conducting and TE polarized waves are incident at different angles according to the present invention.

Fig. 8 is a diagram of S21 when the PIN tube is conducted and TM polarized waves are incident at different angles according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the attached drawing figures:

as shown in fig. 1 to 4, the present invention provides a broadband reconfigurable frequency selective surface based on a single-sided loaded PIN diode, which includes a dielectric plate 1 and metal units distributed on the upper and lower surfaces of the dielectric substrate. Wherein the first metal unit of the upper surface comprises a first metal structure 2 and a PIN diode 3, and the second metal unit of the lower surface comprises a second metal structure 2-1.

As shown in fig. 3, the metal unit on the upper surface of the dielectric plate has a period size a of 8.2mm, the first metal structure 2 includes a first square ring metal patch having an outer peripheral side length equal to the unit period size, a ring width w of 0.6mm, a second square ring metal patch having an outer peripheral side length smaller than the unit period size, an outer peripheral side length a1 of 5.6mm, a ring width w2 of 0.7mm, and a first square ring metal patch having a side length a2 of 2.2 mm. Wherein each side of the outermost first square ring metal patch is interrupted by the middle and connected by a PIN diode 3, and the PIN diodes on the two parallel metal sides have the same direction.

As shown in fig. 4, the second metal unit on the lower surface of the dielectric board is a metal patch structure, and the patch structure can be regarded as etching a rectangular groove on each side of the second square metal patch, and the four etched rectangular grooves are distributed symmetrically up and down and left and right, the side length of the square metal patch without etching the rectangular groove is f ═ 5.2mm, the length y of the etched rectangular groove is 1.1mm, and the width x is 1 mm.

When the PIN diode is conducted, the upper surface of the dielectric plate can be regarded as a double-square-shaped slit ring array, the lower surface of the dielectric plate is a fractal square metal patch array, and the two layers of FSSs are mutually coupled to resonate in an X wave band and present a transmission state; when the PIN diode is cut off, the upper surface of the dielectric plate can be regarded as a metal patch array and comprises a cross patch, a square ring and a square patch, the lower surface is a fractal square metal patch array, and the two layers of FSSs are mutually coupled to resonate in an X wave band and are in a reflecting state.

The invention is described in further detail below with reference to simulation examples.

Examples

The dielectric substrate selected by the invention is a 5880 board with the dielectric constant of 2.2 and the thickness h of 1.016mm, the thickness of the copper foil on the surface of the dielectric board is 17.5 mu m, and the type of the PIN diode is DSM8100-000.

Specific dimensions of the FSS are shown in fig. 1-4 and table 1:

TABLE 1

a/mm	h/mm	w/mm	a1/mm	a2/mm
					8.2	1.016	0.6	5.6	2.2
y/mm	f/mm	w2/mm	s/mm	x/mm
					1.1	5.2	0.7	0.4	1

Fig. 5-8 are S parameters of a designed reconfigurable FSS simulated under electromagnetic simulation software CST. When the structure is in a reflection state, S21 parameters of the structure are all smaller than-20 dB in an operating frequency band; in the transmission state, the S11 parameter is less than-20 dB in the working frequency band, so the relevant curves are listed in the figure.

Fig. 5 is a diagram of S11 when TE polarized waves are incident at different angles in the off state of the diode. The incident angle is 0 degree, and the-2 dB frequency range is 5.25 GHz-12.66 GHz; the incident angle is 15 degrees, and the-2 dB frequency range is 5 GHz-12.58 GHz; the incident angle is 30 degrees, and the-2 dB frequency range is 5 GHz-12.41 GHz; the incident angle is 45 degrees, and the-2 dB frequency range is 5 GHz-12.33 GHz.

Fig. 6 is a diagram of S11 when TM polarized waves are incident at different angles in the off state of the diode. The incident angle is 0 degree, and the-2 dB frequency range is 5 GHz-12.66 GHz; the incident angle is 15 degrees, and the-2 dB frequency range is 5.33 GHz-12.75 GHz; the incident angle is 30 degrees, and the-2 dB frequency range is 5.88 GHz-12.8 GHz; the incident angle is 45 degrees, and the-2 dB frequency range is 6.88 GHz-12.88 GHz.

Fig. 7 is a diagram of S21 when TE polarized waves are incident at different angles in the on state of the diode. The incident angle is 0 degree, and the-2 dB frequency range is 7.25 GHz-12.1 GHz; the incident angle is 15 degrees, and the-2 dB frequency range is 7.33 GHz-12.1 GHz; the incident angle is 30 degrees, and the-2 dB frequency range is 7.7 GHz-12.1 GHz; the incident angle is 45 degrees, and the-2 dB frequency range is 8 GHz-12.1 GHz.

Fig. 8 is a diagram of S21 when TM polarized waves are incident at different angles in the on state of the diode. The incident angle is 0 degree, and the-2 dB frequency range is 7.58 GHz-12.13 GHz; the incident angle is 15 degrees, and the-2 dB frequency range is 7.58 GHz-12.13 GHz; the incident angle is 30 degrees, and the-2 dB frequency range is 7.42 GHz-12.1 GHz; the incident angle is 45 degrees, and the-2 dB frequency range is 7.3 GHz-12.1 GHz.

Therefore, the oblique incidence angle is in the range of 0-45 degrees, the-2 dB bandwidth of the reconfigurable FSS in the transmission and reflection states can reach 4GHz, and the reconfigurable FSS has the advantages of dual polarization in a wide frequency band and insensitivity to the oblique incidence angle.