A broadband metasurface radome for slot antenna arrays

Abstract

This invention relates to the field of antenna technology, specifically to a broadband metasurface radome for slotted antenna arrays. It includes a connected slotted array antenna and a metasurface; the metasurface comprises, from top to bottom, a second radome, a first radome, and a coded metasurface. This invention organically combines the coded metasurface, the radome, and the slotted antenna array by adding slots. This combination of the coded metasurface and the radome overcomes the narrow bandwidth limitation of the coded metasurface and the lack of RCS reduction in the radome's passband, thus broadening the overall RCS reduction bandwidth.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and more specifically to a broadband metasurface radome for slot antenna arrays. Background Technology

[0002] Drones offer advantages such as low cost, high degree of freedom, and reduced risk to personnel. However, with the development of radar technology, how to enable drones to penetrate radar blockades and reach designated locations has become an unavoidable problem, making the requirement for low RCS (Radar Cross Section) even more urgent. While the drone's fuselage can be coated with stealth materials, the airborne antenna, acting as the drone's "ears," needs to be exposed outside the fuselage to ensure normal radiation performance, making it easily detectable by the enemy. Therefore, reducing the RCS of the airborne antenna is crucial.

[0003] Existing coded metasurfaces (CMs) and multilayer bandstop frequency selective radomes (FSAs) are commonly used to reduce the radar cross section (RCS) of antennas, but they have the following problems: On the one hand, the coded metasurfaces (CMs) have a narrow RCS reduction bandwidth, and it is difficult for the coded metasurfaces (CMs) to conform to airborne antennas; on the other hand, existing frequency selective radomes (FSSs) have narrow absorption bands, wide transition bandwidths, and high insertion loss in the passband, resulting in poor absorption efficiency and antenna radiation gain in the transition band, and FSSs do not have RCS reduction capabilities in the passband. Summary of the Invention

[0004] To address the problems mentioned in the prior art, this invention proposes a broadband metasurface radome for slot antenna arrays to solve the problem of high antenna RCS in the prior art.

[0005] The present invention provides a broadband metasurface radome for slotted antenna arrays, comprising a connected slotted array antenna and a metasurface; the metasurface comprises a second antenna radome, a first antenna radome, and a coded metasurface arranged sequentially from top to bottom.

[0006] Preferably, the slot array antenna includes a first dielectric layer, the lower surface of which is printed with feed lines, and the upper surface of which is provided with radiating slots.

[0007] Preferably, the feed line and the central axis of the lower surface of the first dielectric layer are located on the same straight line;

[0008] Four power feeding slots are provided on the lower surface of the first dielectric layer. The four power feeding slots are all perpendicular to the central axis of the lower surface of the first dielectric layer and are symmetrically distributed about the central axis.

[0009] Preferably, the upper surface of the first dielectric layer is provided with four radiation slots, all of which are parallel to the central axis of the lower surface of the first dielectric layer and are symmetrically distributed about the central axis.

[0010] Preferably, the coded metasurface includes two types of coded units with the same structure but different sizes, wherein the smaller coded unit is coded as "0" and the larger coded unit is coded as "1".

[0011] Preferably, the coded metasurface has a slot of the same size as the feed slot, and the coded metasurface is combined with the slot array antenna by loading the slot.

[0012] Preferably, the encoding unit includes a second dielectric layer of the same size as the first dielectric layer. The surface of the second dielectric layer is provided with a first X-shaped metal structure and a second X-shaped metal structure. The first X-shaped metal structure is located at the center of the second dielectric layer, and the second X-shaped metal structure is sleeved on the outside of the first X-shaped metal structure.

[0013] Preferably, the first radome includes a base layer and a Jerusalem cross element disposed on the base layer.

[0014] Preferably, the second radome includes a bottom layer and a composite cross unit disposed at the center of the bottom layer surface, wherein each end of the composite cross unit is connected to a resistor.

[0015] The first and second antenna covers together form a frequency-selective absorber.

[0016] Compared with the prior art, the present invention achieves the following technical effects:

[0017] This invention organically combines a coded metasurface, a radome, and a slotted antenna array by loading slots. The combination of the coded metasurface and the radome not only compensates for the narrow bandwidth of the coded metasurface, but also compensates for the lack of RCS reduction function in the passband of the radome, thus broadening the overall RCS reduction bandwidth. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 This is a side view of the slot array antenna of the present invention;

[0020] Figure 3 This is a schematic diagram of the lower surface of the first dielectric layer of the present invention;

[0021] Figure 4 This is a schematic diagram of the upper surface of the first dielectric layer of the present invention;

[0022] Figure 5 This is a schematic diagram of the coded metasurface of the present invention;

[0023] Figure 6 This is a schematic diagram of the encoding unit of the present invention;

[0024] Figure 7 This is a schematic diagram of the first and second antenna covers of the present invention;

[0025] Figure 8 This is a schematic diagram of the Jerusalem cross unit of the present invention;

[0026] Figure 9 This is a schematic diagram of the composite cross unit of the present invention;

[0027] Figure 10 This is a schematic diagram illustrating the operation of the present invention;

[0028] Figure 11 These are the simulated E-plane and H-plane radiation patterns of this invention;

[0029] Figure 12 This is a comparison diagram of the reduction in RCS during normal incidence according to the present invention;

[0030] Figure 13 This is a comparison diagram of the RCS reduction of the oblique incidence of the present invention.

[0031] Reference numerals: 1. Slot array antenna; 2. Coding metasurface; 3. First radome; 4. Second radome; 5. First dielectric layer; 6. Second dielectric layer; 7. Feed line; 8. Feed slot; 9. Radiation slot. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0033] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used merely for descriptive distinction and have no special meaning.

[0035] like Figure 1 The diagram shown is a schematic diagram of the structure of the present invention. The present invention provides a broadband metasurface radome for slot antenna arrays, including a connected slot array antenna 1 and a metasurface; the metasurface includes a first radome 3, a second radome 4 and an coded metasurface 2 arranged sequentially from top to bottom.

[0036] In the embodiments, as shown Figure 2 , Figure 3 as well as Figure 4 As shown, the slot array antenna 1 includes a first dielectric layer 5, with a feed line 7 printed on the lower surface of the first dielectric layer 5, and a radiation slot 9 provided on the upper surface of the first dielectric layer 5. The feed line 7 and the central axis of the lower surface of the first dielectric layer 5 are located on the same straight line; wherein four feeding slots 8 are provided on the lower surface of the first dielectric layer 5, and the four feeding slots 8 are all perpendicular to the central axis of the lower surface of the first dielectric layer 5, and are all symmetrically distributed about the central axis.

[0037] In the embodiments Figure 3 This is a schematic diagram of the lower surface of the first dielectric layer 5. In this embodiment, the feed line 7 is a fork-shaped microstrip feed line 7, wherein the feed line 7 and the central axis of the lower surface of the first dielectric layer 5 are on the same straight line. The feed line 7 is located on a patch at the center of the first dielectric layer 5. The patch has four feeding slots 8, which are located in pairs at both ends of the central axis and are symmetrically distributed along the central axis. All four feeding slots 8 are arranged laterally. Figure 3 The specifications are WS = 1mm, La1 = 21.46 mm, Wa = 1mm, LS = 14mm, and La2 = 14mm.

[0038] Implementation, for example Figure 4 The diagram shows the upper surface of the first dielectric layer 5. The upper surface of the first dielectric layer 5 is provided with four radial slots 9. The four radial slots 9 are the same size and specifications as the power feeding slots 8. The difference is that the four radial slots 9 are set in different directions than the power feeding slots 8. The four radial slots 9 are symmetrically distributed in pairs about the central axis, and the radial slots 9 are all set vertically.

[0039] like Figure 2 , Figure 5 , Figure 6 As shown, in this embodiment, the coded metasurface 2 includes two types of coded units with the same structure but different sizes, wherein the smaller coded unit is coded as "0" and the larger coded unit is coded as "1". Figure 5It consists of several coding units with two types of codes: "0" and "1". The coding metasurface 2 has a slot, and the size of the slot is the same as that of the feeding slot 8. The coding metasurface 2 is combined with the slot array antenna 1 by loading the slot. This can reduce the RCS of the slot antenna while ensuring normal radiation.

[0040] The encoding unit includes a second dielectric layer 6. A first X-shaped metal structure and a second X-shaped metal structure are disposed on the surface of the second dielectric layer 6. The first X-shaped metal structure is located at the center of the second dielectric layer 6, and the second X-shaped metal structure is sleeved on the outside of the first X-shaped metal structure. In this embodiment, the encoding metasurface 2 is disposed on the second dielectric layer 6, and the thickness of the second dielectric layer 6 is 1.5 mm. Figure 6 The structure of the encoding unit is such that the first X-shaped metal structure is located at the center of the second dielectric layer 6, and rectangular pieces are provided at the middle and ends of the first X-shaped metal structure; in the embodiment, the second X-shaped metal structure is located outside the first X-shaped metal structure and wraps around the first X-shaped metal structure.

[0041] like Figure 6 As shown, the specifications of the encoding unit are L=5mm, La1=1.3mm, La2=0.9mm, Lb1=0.5mm, Lb2=0.2mm, Wa1=1.9mm, Wa2=1.1mm, Wb1=0.1mm, Wb2=v / 3, Ts=0.15mm; where Figure 6 In this context, v represents the design variable. Specifically, the design variable v for coding unit "0" is 1.5 mm, and the design variable v for coding unit "1" is 2.7 mm.

[0042] like Figure 7 As shown, in this embodiment, the first antenna cover 3 includes a base layer and a Jerusalem cross unit disposed on the base layer; the second antenna cover 4 includes a bottom layer and a composite cross unit disposed at the center of the bottom layer surface, wherein the ends of the composite cross unit are all connected to resistors.

[0043] In this embodiment, the first radome 3 is selected from the common slotted Jerusalem-shaped frequency selective radome (FSS), specifically including a base layer and Jerusalem cross elements disposed on the base layer, wherein, for example... Figure 7 and Figure 8 As shown, the specific specifications are as follows: the thickness of the base layer t2 is 0.805mm, W=5mm, Lf1=1.9mm, Lf2=1.66mm, and g1=0.05mm.

[0044] In the embodiment, the second radome 4 is a band-stop frequency selective radome (FSA) with a composite cross-shaped structure and a loaded resistor. Specifically, it includes a bottom layer and a composite cross-shaped element disposed on the bottom layer, such as... Figure 7 and Figure 9As shown, the specific specifications are as follows: the thickness of the bottom layer t1 is 0.805mm, the air layer h1 between the bottom layer and the base layer is 1.9mm, La1=2mm, La2=2.2mm, La3=1.2mm, La4=0.65mm, La5=0.6, La6=0.3mm, La7=0.1mm, and the resistance of the resistor is 154Ω.

[0045] In this embodiment, the first antenna cover 3 and the second antenna cover 4 are combined to form a frequency selective absorber (FSR).

[0046] Implementation, for example Figure 10 As shown, different colored arrows are used to indicate out-of-band incoming waves, in-band incoming waves, and antenna-radiated waves. It can be seen that the blue arrow represents out-of-band incoming waves. When passing through the second radome 4 (FSA), some of the incoming wave energy is absorbed and blocked, and the out-of-band incoming waves that pass through the second radome 4 (FSA) are reflected when they encounter the first antenna radome 3 (FSS) and then absorbed by the second radome 4 (FSA).

[0047] When facing out-of-band incoming waves, the first radome 3 (FSS) acts as a metal floor, and the red arrow indicates in-band incoming waves. In-band incoming waves pass through the first radome 3 and the second radome 4 with almost no obstruction. After reaching the coding metasurface 2, the in-band incoming waves are scattered in various directions.

[0048] The yellow arrows indicate the radiated waves of the antenna. The basic operating state of the antenna can be achieved with minimal loss through the coded metasurface 2, the first antenna radome 3 (FSS), and the second antenna radome 4 (FSA).

[0049] Out-of-band incoming waves can have their reflected energy reduced by repeated absorption by the second-day radome 4 (FSA), thereby reducing the RCS and greatly shortening the detection range of enemy radar. In-band incoming waves can also have their RCS reduced by the diffuse reflection of the digitally coded super-formatted surface, ultimately achieving both in-band and out-of-band RCS reduction.

[0050] Furthermore, all three metasurfaces are composed of centrosymmetric structures, which means that the proposed overall antenna structure can reduce the RCS of incident electromagnetic waves with both TE and TM polarization.

[0051] like Figure 11 As shown, the embodiment combines the coded metasurface 2 with the slotted array antenna 1 by loading slots, resulting in lower in-band insertion loss. Figure 11 In the 19GHz transmission band, the slot antenna gain loss is only 0.6dB after loading three layers of metasurface.

[0052] like Figure 12As shown, the RCS reduction bandwidth of the antenna is greatly improved by combining the coded metasurface 2 and the band-stop frequency selective radome. The simulation results of the metal plate, the FSR only, and the FSR and CM are compared. It is shown that when only the FSR is loaded, the low frequency band with a single-station RCS of less than -10dB is 11.7-17.5GHz, and the high frequency band is 21.4-32.2GHz. The absorption effect of the FSR is very poor in the transition band, and the FSR has almost no RCS reduction effect in the passband.

[0053] The black curve represents the cases with both FSR and CM applied. It can be seen that after applying CM, compared to applying only FSR, the single-site RCS at 19 GHz (near the passband of FSR) is significantly reduced. After applying CM and FSR, the single-site RCS of slot array antenna 1 is reduced by more than 10 dB in the 11.7–32.2 GHz frequency band. Figure 13 It can be seen that the RCS reduction capability of the second antenna radome 4, the first antenna radome 3, and the coded metasurface 2 designed in this invention will slightly decrease as the incident angle increases, but overall it can still guarantee more than 7.5dB, proving that the antenna radome has good angular stability.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A broadband metasurface radome for slotted antenna arrays, characterized in that, It includes a connected slot array antenna and a metasurface; the metasurface includes a second antenna radome, a first antenna radome, and a coded metasurface arranged sequentially from top to bottom; The slot array antenna includes a first dielectric layer, with a radiation slot on the upper surface of the first dielectric layer and four feed slots on the lower surface of the first dielectric layer. The coding metasurface includes two coding units with the same structure but different sizes; the coding metasurface has a slot with the same size as the feed slot, and the coding metasurface is combined with the slot array antenna by loading the slot. The encoding unit includes a second dielectric layer of the same size as the first dielectric layer. The surface of the second dielectric layer is provided with a first X-shaped metal structure and a second X-shaped metal structure. The first X-shaped metal structure is located at the center of the second dielectric layer. The middle and end parts of the first X-shaped metal structure are provided with rectangular pieces. The second X-shaped metal structure is sleeved on the outside of the first X-shaped metal structure. The first radome includes a base layer and a slotted Jerusalem cross element disposed on the base layer; The second radome includes a bottom layer and a composite cross unit disposed at the center of the bottom layer surface, wherein each end of the composite cross unit is connected to a resistor.

2. The broadband metasurface radome for slotted antenna arrays according to claim 1, characterized in that, Feed lines are printed on the lower surface of the first dielectric layer.

3. The broadband metasurface radome for slotted antenna arrays according to claim 2, characterized in that, The feed line is on the same straight line as the central axis of the lower surface of the first dielectric layer; The four power supply gaps are all perpendicular to the central axis of the lower surface of the first dielectric layer, and are symmetrically distributed about the central axis.

4. A broadband metasurface radome for slotted antenna arrays according to claim 2, characterized in that, The upper surface of the first dielectric layer is provided with four radiation slots, all of which are parallel to the central axis of the lower surface of the first dielectric layer and are symmetrically distributed about the central axis.

5. A broadband metasurface radome for slotted antenna arrays according to claim 1, characterized in that, The smaller coding unit is encoded as "0", and the larger coding unit is encoded as "1".

6. A broadband metasurface radome for slotted antenna arrays according to claim 1, characterized in that, The first and second antenna covers together form a frequency-selective absorber.

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