JP3839606B2 - Frequency selective mirror surface - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a frequency selective mirror that reflects radio waves in a specific frequency band among a plurality of radio waves in a predetermined frequency band and transmits radio waves in other frequency bands, or transmits radio waves in a specific frequency band and other The present invention relates to a frequency selective mirror that reflects radio waves in a frequency band.
[0002]
[Prior art]
Conventionally, as a frequency selective mirror surface constituted by a dielectric and a plurality of resonant elements made of a metal foil disposed on the surface of the dielectric, for example, VDAgraval et.al., “Design of a Dichroic Cassegrain Subreflector, "IEEE Trans. Antennas Propagat., Vol. AP-27, No. 4, pp. 466-473, July 1979. FIG. 8 is a front view showing a conventional frequency selective mirror surface shown in the above-mentioned document. 9 is a cross-sectional view taken along the line IX-IX in FIG. In the figure, 11 is a planar dielectric, 12 is a metal foil, and 13 is a resonant element made of the metal foil 12.
[0003]
Resonating elements 3 made of cross-dipole-shaped metal foils 12 having the same dimensions are arranged on a planar dielectric 11 periodically and in a lattice shape so that the resonant elements 3 resonate in a predetermined frequency band F _1. The shape, dimensions, and arrangement periods D _x and D _y are determined.
[0004]
Next, the operation will be described. When a radio wave in the resonance frequency band F ₁ is incident, the resonance element 13 made of the metal foil 12 resonates, a current flows on the resonance element 13, and the resonance element 13 re-radiates the radio wave in the reflection direction and the transmission direction. . At this time, the radio wave re-radiated in the transmission direction cancels the incident wave, and only the radio wave re-radiated in the reflection direction remains.
[0005]
When a radio wave other than the frequency band F ₁ , for example, a radio wave in the frequency band F ₂ is incident, no current flows on the resonance element 13 and the incident wave passes through the dielectric 11 as it is. Thus, for example, when radio waves of _two frequency bands F ₁ and F ₂ are incident, the radio waves of the frequency band F ₁ are reflected by the frequency selection mirror surface, and the radio waves of the frequency band F ₂ are transmitted through the frequency selection mirror surface, thereby selecting the frequency. The mirror surface operates as a band reflection type filter that demultiplexes the radio waves of these frequency bands F ₁ and F ₂ .
[0006]
Further, as a frequency selective mirror surface composed of a metal film and a resonant element comprising a plurality of holes opened in the metal film, CCChen, “Transmission of Microwave Through Perforated Flat Plates of Finite Thickness,” IEEE Trans. Microwave Theory and Vol.MTT-21, No.1, pp.1-6, Jan. 1973. FIG. 10 is a front view showing a conventional frequency selective mirror surface shown in the above-mentioned document. 11 is a cross-sectional view taken along the line XI-XI in FIG. In the figure, 21 is a planar dielectric, 24 is a metal film, 25 is a hole, and 23 is a resonant element comprising a hole 25.
[0007]
Resonant elements 23 each having a circular hole 25 of the same size are periodically arranged on a planar metal film 24 bonded to the dielectric 21 so that the resonant element 23 resonates in a predetermined frequency band F _1. The shape, dimensions, and arrangement periods D _x and D _y are determined.
[0008]
Next, the operation will be described. When a radio wave in the resonance frequency band F ₁ is incident, the resonance element 23 formed by the hole 25 resonates, an electric field is induced on the resonance element 23, and the resonance element 23 re-radiates the radio wave in the reflection direction and the transmission direction. . At this time, the radio wave re-radiated in the reflection direction cancels the reflected wave from the metal film 24, and only the radio wave re-radiated in the transmission direction remains.
[0009]
When a radio wave other than the frequency band F ₁ , for example, a radio wave in the frequency band F ₂ is incident, no electric field is induced on the resonance element 23 and the incident wave is reflected as it is by the metal film 24. Thus, for example, when radio waves in _two frequency bands F ₁ and F ₂ are incident, the radio waves in the frequency band F ₁ are transmitted through the frequency selection mirror surface, and the radio waves in the frequency band F ₂ are reflected on the frequency selection mirror surface, thereby selecting the frequency. The mirror surface operates as a band-pass filter that demultiplexes the radio waves of these frequency bands F ₁ and F ₂ .
[0010]
As a modification of the above-described conventional example, there is one shown in TKWu “Frequency selective surface and grid array”, chap. 4, Wiley, New York, 1995. FIG. 12 is a front view showing a conventional frequency selective mirror shown in the above-mentioned document. 13 is a cross-sectional view taken along line XIII-XIII in FIG.
[0011]
Resonating elements 33 made of circular double ring-shaped metal foils 32 of the same size are periodically arranged in a lattice pattern on a planar dielectric 31, and the outer ring 32 a has a predetermined frequency band F ₁ . the inner ring 32b has the shape, size, arrangement period D _x and D _y are determined so as to resonate at a predetermined frequency band _{F 2 (F 1 <F 2} ).
[0012]
Next, the operation will be described. When radio waves in the resonance frequency bands F ₁ and F ₂ are incident, the resonance element 33 made of the metal foil 32 resonates, a current flows on the resonance element 33, and the resonance element 33 transmits radio waves in the reflection direction and the transmission direction. Re-radiate. At this time, the radio wave re-radiated in the transmission direction cancels the incident wave, and only the radio wave re-radiated in the reflection direction remains.
[0013]
Further, when radio waves other than the frequency bands F ₁ and F ₂ , for example, radio waves in the frequency band F ₃ are incident, no current flows on the resonance element 33 and the incident wave passes through the dielectric 31 as it is. Therefore, for example, when radio waves of _three frequency bands F ₁ , F ₂ and F ₃ are incident, the radio waves of frequency bands F ₁ and F ₂ are reflected by the frequency selection mirror surface, and the radio waves of frequency band F ₃ are reflected by the frequency selection mirror surface. The frequency selective mirror surface operates as a band reflection type filter that demultiplexes the radio waves of these frequency bands F ₁ , F ₂ and F ₃ .
[0014]
As the multiple resonance elements having a plurality of resonance frequency bands as described above, among the resonance element shape examples shown in FIG. 3, a rectangular multiple ring type (c), a circular multiple ring type (f), a Jerusalem cross type (h) etc.
[0015]
[Problems to be solved by the invention]
Since the conventional frequency selective mirror surface is configured as described above, when the shape of the resonant element is other than a multiple resonant element such as a multiple ring type or a Jerusalem cross type, the resonant frequency band is basically an arbitrary one. In order to obtain a wide resonance frequency band or multiple resonance frequency bands, which are only a single frequency band, it is necessary to use this frequency selective mirror layer in multiple layers, which increases the thickness and weight. There was a problem such as.
[0016]
In addition, even when the shape of the resonant element is a multiple resonant element, if the ratio of the highest resonant frequency band to the lowest resonant frequency band among the plurality of resonant frequency bands is extremely large, the highest resonant frequency band, Since the arrangement interval is too large with respect to the wavelength, there is a problem that a grating lobe is generated in which the reflected wave is reflected in a direction other than a predetermined angle. For this reason, there has been a problem that a desired bandwidth cannot be sufficiently secured.
[0017]
Specifically Then on the issue of the grating lobe occurrence, the conventional example of FIG. 12 and FIG. 13, in order to obtain a high resonance frequency band F _2, the extreme decreasing the inner ring 32b, the arrangement interval reflects Therefore, the grating lobe is increased with respect to the predetermined wavelength λ. In order not to generate the grating lobes, it is necessary to set the arrangement interval to λ / 2 or less with respect to a predetermined wavelength λ to be reflected. Therefore, in the conventional example of FIGS. 12 and 13, it is difficult to widen the width of the highest resonance frequency band and the lowest resonance frequency band.
[0018]
The present invention has been made to solve the above-described problems, and a frequency selection mirror having a wide resonance frequency band or a plurality of resonance frequency bands without generating a grating lobe on a single-layer frequency selection mirror surface. The purpose is to obtain a mirror surface.
[0019]
[Means for Solving the Problems]
The frequency selective mirror surface according to the present invention is a frequency selective mirror surface in which resonant elements made of a curved or planar dielectric and a plurality of metal foils disposed on the surface of the dielectric are periodically arranged. resonating element, a plurality of types of different open configuration is provided by a number sequence, the arrangement period is characterized by being a different between the same and different between allogeneic.
[0020]
Further, another frequency selective mirror surface according to the present invention is a frequency selective mirror surface in which a curved or planar metal film and a resonance element including a plurality of holes opened in the metal film are periodically arranged. resonating element, a plurality of types of different open configuration is provided by a number sequence, also the arrangement period is characterized by being a different between the same and different between allogeneic.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a front view of a frequency selective mirror surface of the present invention. 2 is a cross-sectional view taken along the line II-II in FIG. In the figure, reference numeral 1 is a planar dielectric, 2a and 2b are metal foils, and 3 is a resonant element made of metal foils 2a and 2b. On the planar dielectric 1, a plurality of two types of ring-shaped metal foils 2a and 2b having different diameters are arranged at different periods. The radius of the metal foil 2a is R1, and the radius of the metal foil 2b is R2.
[0022]
The ring-shaped metal foils 2a and 2b each function as the resonance element 3, but the metal foils 2a and 2b resonate in the frequency bands F ₁ and F ₂ (F ₁ <F ₂ ), respectively. The arrangement periods D _x1 , D _y1 and D _x2 , D _y2 of the metal foils 2a and 2b are given dimensions in a range in which no grating lobe is generated at each resonance frequency. That is, even if the radius R ₂ of the metal foil 2b on the high resonance frequency band F2 side is reduced, the arrangement interval D _x2 , D _y2 does not increase with respect to the predetermined wavelength λ to be reflected, and the grating・ Lobes are not generated.
[0023]
Next, the operation will be described. When a radio wave in the resonance frequency band F ₁ is incident, the resonance element 3 made of the ring-shaped metal foil 2 a having the radius R ₁ resonates, a current flows on the resonance element 3, and the resonance element 3 is reflected and transmitted. Re-radiate radio waves in the direction and direction. At this time, the radio wave re-radiated in the transmission direction cancels the incident wave, and only the radio wave re-radiated in the reflection direction remains.
[0024]
When a radio wave in the resonance frequency band F ₂ is incident, the resonance element 3 made of the ring-shaped metal foil 2b having the radius R ₂ resonates and re-radiates in the reflection direction according to the same principle as described above. Only radio waves remain.
[0025]
When radio waves other than the frequency bands F ₁ and F ₂ , for example, radio waves in the frequency band F ₃ are incident, no current flows on any of the resonance elements 3, and the incident wave passes through the dielectric 1 as it is. Therefore, for example, when radio waves of _three frequency bands F ₁ , F ₂ and F ₃ are incident, the radio waves of frequency bands F ₁ and F ₂ are reflected by the frequency selection mirror surface, and the radio waves of frequency band F ₃ are reflected by the frequency selection mirror surface. The frequency selective mirror surface operates as a band reflection type filter that demultiplexes the radio waves of these frequency bands F ₁ , F ₂ and F ₃ .
[0026]
That is, since the resonance frequency bands F ₁ and F ₂ can be set independently, a frequency selective mirror surface having a plurality of resonance frequency bands can be realized. Further, by providing the resonance frequency bands F ₁ and F ₂ adjacent to each other, a frequency selective mirror surface having a wide resonance frequency range can be realized.
[0027]
In the present embodiment, the two types of resonant elements 3 made of the metal foils 2a and 2b differ only in diameter and have the same circular shape, but each resonant element 3 does not physically interfere. The shapes do not necessarily have to coincide with each other as long as the shape, size, and arrangement cycle.
[0028]
FIG. 3 shows an example of the shape of the resonant element 3. Further, the number of combinations of different shapes of the resonant elements 3 is not necessarily two types, and various types of resonant elements 3 may be arranged as necessary. Furthermore, the arrangement of the resonant elements 3 may be either a square shape shown in FIG. 4 or a triangular shape shown in FIG.
[0029]
Embodiment 2. FIG.
FIG. 6 is a front view showing another example of the frequency selective mirror surface of the present invention. 7 is a cross-sectional view taken along the line VII-VII in FIG. In the figure, 1 is a planar dielectric, 4 is a metal film covering the entire surface of the dielectric 1, 5a and 5b are holes of a predetermined shape drilled in the metal film 4, and 6 is a hole 5a and 5b. It is a resonant element.
[0030]
In the planar metal film 4 bonded to the dielectric 1, a plurality of rectangular holes 5 a and 5 b having two different sizes are provided with different periods. The rectangular holes 5a and 5b function as the resonance element 6, but the hole 5a having the dimension L _x1 × L _{y1 and} the hole 5b having the dimension L _x2 × L _y2 are frequency bands F ₁ and F ₂ (F ₁ < F ₂ ), and the arrangement periods D _x1 , D _y1 and D _x2 , D _y2 are given dimensions that do not cause grating lobes at the respective resonance frequencies.
[0031]
Next, the operation will be described. When a radio wave in the resonance frequency band F ₁ is incident, the resonance element 6 composed of the rectangular hole 5a having the dimension L _x1 × L _y1 resonates, an electric field is induced on the resonance element 6, and the resonance element 6 reflects in the reflection direction. And re-radiate radio waves in the transmission direction. At this time, the radio wave re-radiated in the reflection direction cancels the reflected wave from the metal film 4, and only the radio wave re-radiated in the transmission direction remains. When a radio wave in the resonance frequency band F ₂ is incident, the resonance element 6 including the rectangular hole 5b having the dimension L _x2 × L _y2 resonates and is re-radiated in the transmission direction by the same principle as described above. Only the remaining radio wave remains.
[0032]
When radio waves other than those in the frequency bands F ₁ and F ₂ , for example, radio waves in the frequency band F 3 are incident, no electric field is induced on any of the resonance elements 6, and the incident waves reflect the metal film 4 as they are. Therefore, for example, when radio waves of _three frequency bands F ₁ , F ₂ and F ₃ are incident, the radio waves of the frequency bands F ₁ and F ₂ are transmitted through the frequency selection mirror surface, and the radio waves of the frequency band F ₃ are frequency selection mirror surfaces. The frequency selective mirror surface operates as a band-pass filter that demultiplexes the radio waves of these frequency bands F ₁ , F _2, and F ₃ .
[0033]
That is, since the resonance frequency bands F ₁ and F ₂ can be set independently, a frequency selective mirror surface having a plurality of resonance frequency bands can be realized. Further, by providing the resonance frequency bands F ₁ and F ₂ adjacent to each other, a frequency selective mirror surface having a wide resonance frequency range can be realized.
[0034]
In the present embodiment, the two types of resonant elements 6 including the holes 5a and 5b differ only in size and have similar shapes, but the shapes and dimensions of the respective resonant elements 6 that do not physically interfere with each other. As long as it is an arrangement period, the shapes do not necessarily have to coincide with each other.
[0035]
FIG. 3 shows an example of the shape of the resonant element 6. Also, the number of combinations of different shapes of the resonant elements 6 is not necessarily two types, and various types of resonant elements 6 may be arranged as necessary. Further, the arrangement of the resonant elements 6 may be either a quadrangular shape shown in FIG. 4 or a triangular shape shown in FIG.
[0036]
【The invention's effect】
The frequency selective mirror according to the present invention is a frequency selective mirror in which a curved or planar dielectric and a plurality of metal foils arranged on the surface of the dielectric are periodically arranged. element, a plurality of types of different open configuration is provided by a number sequence, the arrangement period is characterized by being a different between the same and different between allogeneic. Therefore, a frequency selective mirror surface having a wide resonance frequency band or a plurality of resonance frequency bands can be obtained without generating a grating lobe with a single layer frequency selective mirror surface.
[0037]
In addition, another frequency selective mirror surface according to the present invention is a frequency selective mirror surface in which a curved or planar metal film and a resonance element including a plurality of holes provided in the metal film are periodically arranged. element, a plurality of types of different open configuration is provided by a number sequence, also the arrangement period is characterized by being a different between the same and different between allogeneic. Therefore, a frequency selective mirror surface having a wide resonance frequency band or a plurality of resonance frequency bands can be obtained without generating a grating lobe with a single layer frequency selective mirror surface.
[Brief description of the drawings]
FIG. 1 is a front view of a frequency selective mirror surface of the present invention.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
FIG. 3 is a diagram showing an example of the shape of a resonant element.
FIG. 4 is a diagram showing a square array of resonant elements.
FIG. 5 is a diagram showing a triangular array of resonant elements.
FIG. 6 is a front view showing another example of the frequency selective mirror surface of the present invention.
7 is a cross-sectional view taken along the line VII-VII in FIG.
FIG. 8 is a front view showing a conventional frequency selective mirror surface.
9 is a cross-sectional view taken along the line IX-IX in FIG.
FIG. 10 is a front view showing another conventional frequency selective mirror surface.
11 is a cross-sectional view taken along the line XI-XI in FIG.
FIG. 12 is a front view showing another conventional frequency selective mirror surface.
13 is a cross-sectional view taken along the line XIII-XIII in FIG.
[Explanation of symbols]
1 dielectric, 2a, 2b metal foil, 3, 6 resonant element, 4 metal film, 5 holes.

Claims (2)

In a frequency selective mirror surface in which a resonant element composed of a curved or planar dielectric and a plurality of metal foils arranged on the surface of the dielectric is periodically arranged,
The resonating element, different types of open configuration is provided by a number sequence, its placement period, frequency selective mirror surface, characterized in that there is a different between the same and different between allogeneic. In a frequency-selective mirror surface in which a resonant element composed of a curved or planar metal film and a plurality of holes provided in the metal film is periodically arranged,
The resonating element, different types of open configuration is provided by a number sequence and its placement period, frequency selective mirror surface, characterized in that there is a different between the same and different between allogeneic.

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