A dual-passband adjustable spatial filter periodic structure

Abstract

This invention provides a dual-passband adjustable spatial filter periodic structure, belonging to the field of electromagnetic metamaterials technology. It includes: an upper metal unit layer, an intermediate dielectric layer, and a lower metal feeder unit layer; both the upper and lower metal feeder layers are periodic structures; each period of the upper metal unit layer contains four aperture rings etched, distributed across four quadrants; the four aperture rings have two sizes, with those on the same diagonal having the same size; each aperture ring is symmetrically loaded with four active lumped elements; the center of each aperture ring is electrically connected to the lower metal feeder unit layer via a metal via; each period of the lower metal unit layer is a cross-shaped metal patch structure, with the metal vias connecting to the cross-shaped metal patches via metal patches, and each metal patch connecting the cross-shaped metal patch and the metal via is loaded with a passive lumped inductor.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic metamaterials technology, specifically relating to a dual-passband adjustable spatial filtering periodic structure. Background Technology

[0002] Electromagnetic metamaterials are artificial structural materials composed of periodic or aperiodic arrangements of subwavelength-scale structural units. They have significant applications in antennas and radar communications. In particular, artificial periodic structural materials composed of periodically arranged metallic units of specific shapes can also be called frequency-selective surfaces (FSS). These surfaces can control the transmission and reflection of incident electromagnetic waves at specific frequencies, exhibiting spatial filtering characteristics, and thus can be considered a special type of spatial filter. Due to their unique electromagnetic wave modulation characteristics, frequency-selective surfaces are often applied to radomes to achieve stealth properties.

[0003] Current research primarily focuses on designing passive FSS periodic structures. While these effectively address the out-of-band stealth of the radome, they fail to simultaneously solve the in-band stealth problem. Active FSS periodic structures, by incorporating a series of active devices into a passive periodic structure, allow for the artificial control of spatial filtering characteristics. This reduces the risk of radar detection while ensuring normal antenna operation.

[0004] Currently, there are few domestic designs using active FSS periodic structures for radomes, and research on how to reduce the impact of the feeding structure for active devices on the transmission characteristics of the periodic structure itself is also limited. Furthermore, research on multi-band modulation of active FSS periodic structures is scarce. However, the design and research of active FSS periodic structures will be a future hot topic in the FSS field, and it has significant research value for active radar, radomes, and other related fields. Summary of the Invention

[0005] This invention provides a dual-passband adjustable spatial filter periodic structure. By loading active devices, it achieves dual-passband frequency adjustable characteristics, solves the design problem of the feed circuit for loading active devices, and has good polarization stability. It can be used to cope with radar electronic detection systems with variable operating frequencies in the mid-range and improve survivability in complex electromagnetic environments.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A dual-passband adjustable spatial filter periodic structure includes: an upper metal unit layer, an intermediate dielectric layer, and a lower metal feed line unit layer; both the upper metal unit layer and the lower metal feed line layer are periodic structures.

[0008] In each cycle of the upper metal unit layer, four aperture rings are etched, and the four aperture rings are distributed in four quadrants. The four aperture rings have two sizes, and the aperture rings on the same diagonal have the same size. Four active lumped elements are loaded on each aperture ring in a central axis symmetrical manner. The center of the aperture ring is electrically connected to the lower metal feeder unit layer through a metal via.

[0009] Each cycle of the lower metal unit layer is a cross-shaped metal patch structure. The metal via is connected to the cross-shaped metal patch through the metal patch. A passive lumped inductor is loaded on each metal patch that connects the cross-shaped metal patch and the metal via.

[0010] Furthermore, each periodic unit of the upper metal unit periodic structure of the present invention is a large square unit of the same size. The large square unit is divided into 4 small square units of the same size. 4 aperture rings are etched on the 4 small square units of the same size, and the center of the aperture rings coincides with the center of the small squares.

[0011] Furthermore, the active lumped element loaded in the upper metal unit periodic structure of the present invention is a PIN or a varactor diode.

[0012] Furthermore, the aperture ring described in this invention is a square ring, a hexagonal ring, or a circular ring.

[0013] Furthermore, in the lower metal unit periodic structure of the present invention, each periodic unit is a large square unit of the same size, and the size is the same as that of the upper metal unit periodic structure.

[0014] The cross-shaped thin strip metal patch structure is arranged on the central axis of symmetry of the large square unit. The large square unit is divided into 4 small square units of the same size. The center of each small square unit in the lower layer is connected to the cross-shaped thin strip metal patch through the thin strip metal patch, and together with the cross-shaped thin strip metal patch, they form a central axis symmetric structure patch unit.

[0015] The center positions of the four lower small square units are electrically connected to the center positions of the four upper small square units through metal vias; four passive lumped inductors are loaded onto the four small square metal unit patch structures in a central axis symmetrical manner.

[0016] Furthermore, the thickness of the upper and lower metal unit layers of the present invention is 0.025 mm, the metal is Cu, the thickness of the intermediate dielectric layer h1 is 0.25 mm, the dielectric material is F4B, and the relative permittivity is 2.2.

[0017] Furthermore, in this invention, the period P of the large square unit is 4mm, and the two sizes of aperture rings are denoted as Y1 and Y2 respectively. The distance between aperture ring Y1 and the boundary of the large square is d1 = 0.5mm, and the width is s1 = 0.5mm; the distance between aperture ring Y2 and the boundary of the large square is d2 = 0.3mm, and the width is s2 = 0.3mm.

[0018] Furthermore, the active lumped element of the present invention is a varactor diode C1, and the capacitance value of C1 ranges from 0.01pF to 1pF.

[0019] Furthermore, the width d3 of the elongated metal patch of the present invention is 0.2 mm.

[0020] Furthermore, the passive inductor L1 loaded at the metal patch in each small square unit of the present invention has an inductance of 20nH.

[0021] Beneficial effects

[0022] In this invention, both the upper metal unit layer and the lower metal feeder layer are periodic structures, and the lower and upper layers are electrically connected through an intermediate metal via. The upper metal unit periodic structure is loaded with active lumped elements (such as PIN diodes, varactor diodes, etc.), and the lower metal unit periodic structure is loaded with passive lumped inductors. Through reasonable structural design, as the varactor diode C1 changes from 0.1pF to 0.5pF, the periodic structure can achieve dual-band bandpass adjustable characteristics in the C, X, and Ku bands, and has good polarization stability. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of the overall structure of a dual-passband adjustable spatial filter period;

[0025] Figure 2 This is a diagram of the upper metal unit structure.

[0026] Figure 3 This is a layer diagram of the feeder structure of the lower metal unit;

[0027] Figure 4 Simulation curve of S21 transmission characteristics for dual-passband adjustable spatial filtering period. Detailed Implementation

[0028] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0030] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0031] Figure 1 This invention provides a schematic diagram of a dual-passband adjustable spatial filter periodic structure. The periodic structure includes an upper metal unit layer, an intermediate dielectric layer, and a lower metal feeder unit layer. Both the upper metal unit layer and the lower metal feeder layer are periodic structures.

[0032] In each cycle of the upper metal unit layer, four aperture rings are etched, and the four aperture rings are distributed in four quadrants. The four aperture rings have two sizes, and the aperture rings on the same diagonal have the same size. Four active lumped elements are loaded on each aperture ring in a central axis symmetrical manner. The center of the aperture ring is electrically connected to the lower metal feeder unit layer through a metal via.

[0033] Each cycle of the lower metal unit layer is a cross-shaped metal patch structure. The metal via is connected to the cross-shaped metal patch through the metal patch. A passive lumped inductor is loaded on each metal patch that connects the cross-shaped metal patch and the metal via.

[0034] In one embodiment of this application, the upper metal unit periodic structure consists of a large square unit of the same size. Each large square metal unit can be considered as four small square units of the same size. Two different sizes of aperture slit structures (such as square ring, hexagonal ring, circular ring, or any other annular aperture unit) are etched sequentially on the four small square units at intervals. Four active lumped elements are loaded onto the center position of the slit of each small square metal unit in a central axis symmetrical manner.

[0035] In one embodiment of this application, the lower-layer metal unit periodic structure comprises a large square unit of the same size as the upper-layer structure. A cross-shaped, elongated metal patch structure is arranged on the central axis of symmetry of the large square unit, and like the upper-layer structure, it is divided into four smaller square units of the same size. The center of each smaller square unit in the lower layer is connected to the cross-shaped patch via the same elongated metal patch, forming a centrally symmetrical patch unit. Simultaneously, the centers of the four smaller square units in the lower layer are electrically connected to the centers of the four smaller square units in the upper layer via metal vias. Four passive lumped inductors are loaded onto the four smaller square metal unit patch structures in a centrally symmetrical manner.

[0036] In one embodiment of this application, the thickness of the upper and lower metal unit periodic structures is generally less than 0.05 mm. The middle layer is a dielectric material substrate layer, which serves as the dielectric substrate for the upper and lower metal layers. The relative permittivity is generally between 1.5 and 10, and the thickness is generally less than 5 mm depending on the selected dielectric material.

[0037] Figure 1 This is a schematic diagram of the overall structure of a dual-passband adjustable spatial filter cycle. The upper metal unit layer has two aperture rings, Y1 and Y2, of different sizes, arranged in a crisscross pattern. The centers of these rings are electrically connected to the lower metal feeder unit layer via metal vias. The thickness of both the upper and lower metal unit layers is 0.025 mm, and the metal is Cu. The thickness of the intermediate dielectric layer, h1, is 0.25 mm, and the dielectric material is F4B with a relative permittivity of 2.2.

[0038] Figure 2 This is a diagram showing the dimensions of the upper metal unit layer of a dual-passband adjustable spatial filter periodic structure. The overall large square unit has a period P of 4mm, which can be divided into four smaller square units of 2mm each. The two aperture rings Y1 and Y2 have specific dimensions of d1 = 0.5mm, s1 = 0.5mm, d2 = 0.3mm, and s2 = 0.3mm, respectively. Each ring slot unit has a varactor diode C1 loaded on each of its top, bottom, left, and right sides, with capacitance values ​​ranging from 0.01pF to 1pF. Y1 resonates and transmits at relatively high frequencies, while Y2 resonates and transmits at relatively low frequencies. The four varactor diodes C1 loaded in each of the Y1 and Y2 units respectively allow for adjustable FSS periodic resonant transmission frequencies.

[0039] Figure 3This is a dimension diagram of the lower metal feeder unit layer of a dual-passband adjustable spatial filter periodic structure. The feeder width d3 is 0.2mm, and a passive inductor L1 with a value of 20nH is loaded at the feeder in each small square unit. The feeder layer adopts a cross-axis symmetrical design, which is simpler than the traditional feeder network with straight connections at the center of each unit. A large inductor is loaded at each circular unit, which helps to reduce the impact of the feeder layer on the bandpass insertion loss of the FSS periodic structure.

[0040] Figure 4 The simulation curve of the S21 transmission characteristic of the dual-band adjustable spatial filter period is shown. By adjusting the capacitance value of the varactor diode C1 by applying an external voltage, as the varactor diode C1 changes from 0.1pF to 0.5pF, the periodic structure can achieve dual-band adjustable bandpass characteristics in the C, X, and Ku bands.

[0041] The periodic structure of this invention, through reasonable optimization of the structural parameters of each layer unit, can design an active FSS structure with dual passband tunability within the 2–40 GHz range, while also possessing good polarization stability. This periodic structure can be applied to radar radome stealth design, effectively reducing the in-band RCS and improving radar survivability.

[0042] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a further explanation of the implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dual-passband tunable spatially filtered periodic structure, characterized in that, The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof.

2. The dual passband tunable spatial filter periodic structure of claim 1, wherein, The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof.

3. The dual passband tunable spatial filter periodic structure of claim 1, wherein, The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof.

4. The dual passband tunable spatial filter periodic structure of claim 1, wherein, The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof.

5. The dual passband tunable spatial filter periodic structure of claim 4, wherein, The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof.

6. The dual passband tunable spatial filter periodic structure of claim 1, wherein, The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. The application relates to a periodic structure of a frequency selective surface (FSS) and a preparation method thereof. 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