Disclosure of Invention
An object of the embodiments of the present invention is to provide a frequency selective surface, which aims to solve the problems mentioned in the background art.
The embodiment of the utility model provides a realize like this, a frequency selective surface, the frequency selective surface includes:
three layers of metal patches; each layer of metal patch consists of a plurality of metal patch subunits which are periodically arranged;
the two layers of dielectric substrates are respectively arranged between the three layers of metal patch arrays;
the metal patch sub-units on the top layer and the bottom layer are both in I shapes, and the variable capacitance diodes are arranged in the center of the I-shaped metal patch sub-units; the metal patch subunit in the middle layer is in a straight line shape.
Preferably, the periodic arrangement is a matrix arrangement.
Preferably, the metal patch sub-units of the top layer and the metal patch sub-units of the bottom layer have the same structural size.
Preferably, both ends of the metal patch of the middle layer extend to the edge of the dielectric substrate.
Preferably, the material of the dielectric substrate is an F4B plate.
Preferably, the dielectric constant of the F4B plate is 2.65, and the loss tangent angle is 0.001.
Preferably, the dielectric substrate has a size of length, width, height =6mm × 6mm × 2.5mm with a dimensional error of ± 0.1 mm.
Preferably, the metal patch is made of copper.
Preferably, the thickness of the metal patch is 0.017-0.019 mm.
The embodiment of the utility model provides a pair of frequency selective surface, include: three layers of metal patches; each layer of metal patch consists of a plurality of metal patch subunits which are periodically arranged; the two layers of dielectric substrates are respectively arranged between the three layers of metal patch arrays; the metal patch sub-units on the top layer and the bottom layer are both in I shapes, and the variable capacitance diodes are arranged in the center of the I-shaped metal patch sub-units; the metal patch subunit in the middle layer is in a straight line shape.
Compared with the prior art, the utility model belongs to active device. The utility model has two resonance points by welding the variable capacitance diode at the central part of the I-shaped metal patch subunit, thereby realizing ultra wide band frequency selection; secondly, the utility model discloses a change simultaneously and apply the bias voltage V at varactor, can make its frequency selective characteristics continuously adjustable to the electromagnetic wave, change its filtering performance, solved passive frequency selective surface effectively in case processing is accomplished, its frequency selective characteristics just can not change the defect, can be applicable to more complicated electromagnetic environment. Moreover, the utility model discloses basic structure is simple, and thickness is thin, and easily processing production easily integrates in the system, and the low price has wide prospect in practical application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below 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 are not intended to limit the invention.
The following detailed description is provided for the specific embodiments of the present invention.
As shown in fig. 1, a frequency selective surface is provided for an embodiment of the present invention, the frequency selective surface includes:
three layers of metal patches; each layer of metal patch consists of a plurality of metal patch subunits which are periodically arranged;
the two layers of dielectric substrates are respectively arranged between the three layers of metal patch arrays;
the metal patch sub-units on the top layer and the bottom layer are both in I shapes, and the variable capacitance diodes are arranged in the center of the I-shaped metal patch sub-units; the metal patch subunit in the middle layer is in a straight line shape.
In the embodiment of the present invention, as shown in fig. 1, the top metal patch 1 is printed on the upper surface of the top dielectric substrate 6, the bottom metal patch 3 is printed on the lower surface of the bottom dielectric substrate 7, and the middle metal patch 2 is printed between the top dielectric substrate 6 and the bottom dielectric substrate 7. Each layer of metal patch is composed of a plurality of metal patch subunits which are periodically arranged along the X-axis direction and the Y-axis direction of the medium surface. The top layer varactor 4 is welded at the central part of the metal patch subunit at the top layer, and the bottom layer varactor 5 is welded at the central part of the metal patch subunit at the bottom layer.
The middle metal patch 2 is a typical metal strip grid, and when the electric field component of the incident electromagnetic wave is parallel to the metal strip grid, the metal strip grid is equivalent to a high-pass filter, which can effectively prevent the low-frequency electromagnetic wave from propagating, but does not cause a great influence on the propagation of the high-frequency electromagnetic wave, which is equivalent to an inductor in a circuit. When the low-frequency electromagnetic wave is transmitted, the low-frequency current in the equivalent circuit is guided into the ground under the action of the inductor, and when the high-frequency electromagnetic wave is transmitted, the high-frequency current in the equivalent circuit cannot pass through the inductor and is transmitted to the other end.
The top varactor 4 and the bottom varactor 5 are equivalent to impedances represented by:
z, R, L, C represents a diode impedance, an equivalent resistance, an equivalent inductance, and an equivalent capacitance, respectively.
SMV2019-079LF series varactors produced by Skyworks Solution manufacturers are used as the top varactor 4 and the bottom varactor 5 in this embodiment, and the loading voltages and corresponding data of the top varactor 4 and the bottom varactor 5 in this embodiment are as follows:
VR(V)
|
C(pF)
|
R()
|
L(nH)
|
0
|
2.31
|
4.51
|
0.7
|
-7
|
0.55
|
3.66
|
0.7
|
-14
|
0.31
|
2.86
|
0.7
|
-19
|
0.24
|
2.38
|
0.7 |
wherein, VR, C, R, L represent voltage, equivalent capacitance, equivalent resistance, equivalent inductance loaded on the varactor diode respectively. By changing the voltage VR loaded on the varactor, the equivalent capacitance, the equivalent resistance, and the equivalent inductance of the top varactor 4 and the bottom varactor 5 can be changed, and finally the equivalent impedance of the varactor is changed, which is equivalent to changing the impedance characteristics of the frequency selective surface.
Compared with the prior art, the utility model belongs to active device. The utility model has two resonance points by welding the variable capacitance diode at the central part of the I-shaped metal patch subunit, thereby realizing ultra wide band frequency selection; secondly, the utility model discloses a change simultaneously and apply the bias voltage V at varactor, can make its frequency selective characteristics continuously adjustable to the electromagnetic wave, change its filtering performance, solved passive frequency selective surface effectively in case processing is accomplished, its frequency selective characteristics just can not change the defect, can be applicable to more complicated electromagnetic environment. Moreover, the utility model discloses basic structure is simple, and thickness is thin, and easily processing production easily integrates in the system, and the low price has wide prospect in practical application.
As a preferred embodiment of the present invention, the periodic arrangement is a matrix arrangement.
As a preferred embodiment of the present invention, the metal patch sub-unit of the top layer and the metal patch sub-unit of the bottom layer have the same structural size.
Specifically, as shown in fig. 1 and 2, the top metal patch 1 and the bottom metal patch 3 have the same structural size, and each row and each column in the periodic array are composed of the same metal patch subunits, so that mutual interference is reduced.
As shown in fig. 1, as a preferred embodiment of the present invention, both ends of the middle layer metal patch 2 extend to the edge of the dielectric substrate.
As a preferred embodiment of the present invention, the material of the dielectric substrate is F4B plate.
Specifically, the F4B board is an insulating material with low loss, high dielectric constant and stability, and is often used in mobile communication products, passive devices such as combiners, power splitters, duplexers, filters and couplers, and in the fields of GSM, CDMA and 3G smart antennas, and is a material with excellent performance. In this embodiment, the top dielectric substrate 6 and the bottom dielectric substrate 7 are both made of F4B board.
As a preferred embodiment of the present invention, the F4B board has a dielectric constant of 2.65 and a loss tangent angle of 0.001.
As a preferred embodiment of the present invention, the size of the dielectric substrate is length, width, height =6mm × 6mm × 2.5mm, and the size error is ± 0.1 mm.
Specifically, the top dielectric substrate 6 and the bottom dielectric substrate 7 can reflect electromagnetic waves incident to the frequency selection surface for multiple times, the frequency selection surface can have two resonance points by optimizing the thicknesses of the top dielectric substrate 6 and the bottom dielectric substrate 7, and the frequency selection performance of the device is greatly expanded.
As a preferred embodiment of the present invention, the metal patch is made of copper.
Specifically, the top metal patch 1, the middle metal patch 2 and the bottom metal patch 3 are all copper foils.
As a preferred embodiment of the utility model, the thickness of metal paster is 0.017~0.019 mm.
Example 2
This embodiment is a specific implementation of the frequency selective surface in embodiment 1, where the frequency selective surface operates in a microwave frequency band, and the structure of the frequency selective surface is as follows:
the top dielectric substrate 6 and the bottom dielectric substrate 7 are both in a square structure, the side length P =6mm, and the thickness t =2.5 mm; both of them are made of F4B dielectric plate with copper-coated on both sides, the dielectric constant is 2.65, and the loss tangent angle is 0.001.
The upper surface of the top layer dielectric substrate 6 and the lower surface of the bottom layer dielectric substrate 7 are respectively covered with a top layer metal patch 1 and a bottom layer metal patch 3, and the top layer metal patch 1 and the bottom layer metal patch 3 are metal resonance layers, so that the frequency selection surface has two resonance points. The middle layer metal patch 2 is arranged between the top layer dielectric substrate 6 and the bottom layer dielectric substrate 7. The top metal patch 1 and the bottom metal patch 3 are both composed of I-shaped metal patch subunits arranged in a 35 × 35 array, the arm width w1=0.2mm and the arm spacing d =5.8mm of the I-shaped metal patch subunits, as shown in fig. 3. The central part of the I-shaped metal patch subunit is welded with a variable capacitance diode, the variable capacitance diode is an SMV2019-079LF series variable capacitance diode produced by Skyworks Solution manufacturers, and the length g =1.2 mm. The middle metal patch 2 is composed of a plurality of straight metal patch subunits, and the arm width w2=0.6mm of the straight metal patch subunits is shown in fig. 4. The thicknesses of the top layer metal patch 1, the middle layer metal patch 2 and the bottom layer metal patch 3 are all 0.018 mm.
As shown in fig. 5, a voltage is applied to both ends of the varactor on the top metal patch 1 and the bottom metal patch 3, and the magnitude of the applied voltage is adjusted at the same time, so as to adjust the operating frequency band.
As shown in fig. 6, the operating band of the frequency selective surface shifts to a high frequency with a gradual increase in the reverse bias voltage. When the reverse bias voltage is 0V, the-10 dB working bandwidth of the frequency selection surface is 22.1% (3.55-4.43 GHz); when the reverse bias voltage was increased to 19V, the-10 dB operating bandwidth was 22.1% (4.43-5.53 GHz). And in the continuous adjustable process, the insertion loss in a passband is 0.27-2.6dB, and the return loss is 11.3-35.9 dB.
The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.