JP2001068924A - Layered type aperture antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a mode for propagation of an electromagnetic wave through a dielectric layer installed for matching purpose on a slot and to enable emission of a circularly polarized wave as the electromagnetic wave. SOLUTION: A spatial resonator is formed, which is surrounded with an upper main conductor layer 2 having a circular opening 5 of an upper face of a dielectric base 1, a lower main conductor layer 3, and an antenna conductor wall consisting of a plurality of through-conductors 6 electrically connecting the upper lower main conductor layers 2, 3 around the opening 5 and a sub- conductor layer 7 electrically connecting them, and a cross type slot 4 for feeding is formed to the lower main conductor layer 3. Then the thickness of the spatial resonator is selected to be λ0/8-λ0/2, the diameter of the opening 5 is selected to be λ0/2-3λ0/2, the length of the cross shaped slot 4 is selected to be λ0/4-3λ0/4 and the two slots are in crossing as a cross, where λ0 is the wavelength of a high frequency signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated aperture antenna which is an antenna element suitable for communication using high-frequency signals in a microwave band, a millimeter wave band, or the like, and in particular, can radiate circularly polarized waves. The present invention relates to a stacked aperture antenna.

[0002]

2. Description of the Related Art As an example of an antenna element which has been proposed as an antenna element for emitting an electromagnetic wave of a high frequency signal such as a microwave or a millimeter wave, there is a slot antenna which emits an electromagnetic wave from a slot. Slot antennas are widely used because of their simple structure, and those using a microstrip line, a strip line, a coplanar line, a waveguide line, or the like as a feed line have been proposed.

[0003]

However, in the slot antenna, when electromagnetic waves are radiated from the slot to the free space, the impedance at the radiation interface between the slot and the free space is different, so that the loss due to reflection is large. There was a problem. In addition, since the wavelength is on the order of several millimeters at a high frequency such as a millimeter wave band, the dimensional accuracy of the slot must be within about 1% in order to radiate an electromagnetic wave at a desired frequency to a slot antenna which is a narrow band. For example, a method of forming a slot on a dielectric substrate by a thick film printing method has a problem that it is difficult to satisfy the dimensional accuracy.

On the other hand, in order to reduce the reflection loss at the radiation interface, in a dielectric lens or the like, a dielectric layer having a thickness corresponding to １ ／ of the signal wavelength of the radiated high-frequency signal is provided on the radiation surface. Has been proposed.

However, when this method is applied to a slot antenna, although the loss due to reflection can be reduced,
Since the mode in which the electromagnetic wave propagates in the loaded dielectric layer is also generated at the same time, there is a problem that the main beam is not radiated in the front direction of the antenna but is radiated in the side direction.

When a slot antenna attempts to radiate a circularly polarized wave as a high-frequency signal, an axial ratio of 3 is required.
It is necessary to set a frequency within dB as a desired value, but there is a problem that it is difficult due to the influence of the dimensional accuracy of the slot.

The present invention has been devised to solve such a conventional problem. It is an object of the present invention to reduce the size of the slot while suppressing the reflection loss at the radiation interface between the slot and free space in the slot antenna. It is an object of the present invention to provide a laminated aperture antenna capable of making the polarization of a high-frequency signal radiated at a desired frequency into a circular polarization even if the accuracy is about several percent.

[0008]

The inventor of the present invention has studied the above problems, and as a result, the dielectric layer loaded on the upper surface of the cross-shaped slot in which two slots are crossed and combined. By providing an electrical wall made up of a conductive layer and a through conductor group that are electrically conductive inside and surrounding the cross-shaped slot, it is possible to suppress the mode in which electromagnetic waves propagate through the loaded dielectric layer. I found it. Furthermore, the dimensions of the area surrounded by the electrical wall composed of the electrically conductive conductor layer and the through conductor group, the dimensions of the cross-shaped slot, and the angle at which the two slots forming the cross-shaped slot intersect properly are appropriately determined. By adjusting, even in a cross-shaped slot manufactured with the dimensional accuracy of the thick film printing method, it is possible to radiate electromagnetic waves in a desired frequency band, and the polarization of the high frequency signal radiated from the aperture surface in the far field of the electromagnetic wave It has been found that a laminated aperture antenna capable of converting the light into circularly polarized waves can be obtained.

That is, the laminated aperture antenna of the present invention comprises an upper main conductor layer having a circular opening formed on an upper surface of a dielectric substrate formed by laminating a plurality of dielectric layers; A lower main conductor layer formed at a position opposite to the opening below the substrate, and formed in the dielectric substrate around the opening, and the upper main conductor layer and the lower main conductor layer are formed at predetermined intervals. Forming a spatial resonator surrounded by a plurality of through conductors electrically connected to each other and an antenna conductor wall composed of a sub-conductor layer electrically connecting the plurality of through conductors between the dielectric layers; A laminated aperture antenna in which a cross-shaped slot for supplying a high-frequency signal is formed at a portion of the body layer facing the center of the opening, wherein a signal wavelength of the high-frequency signal in a dielectric substrate is λ. ₀ And the thickness of the spatial resonator is λ ₀ /
8~λ _0/2, the diameter of the opening λ _0/2 ~3 λ ₀ /
2, and the cross-shaped slot slot length lambda _0/4 to 3
It is characterized in that it has as made by intersecting lambda _0/4 of the two slots to cross.

According to the laminated aperture antenna of the present invention,
A cross-shaped slot formed by providing a cross-shaped conductor non-formed portion in the conductor layer is fed with an arbitrary feeder line, and a resonance mode of two slots constituting the cross-shaped slot is generated, thereby obtaining a polarization plane. Can be a slot of a circularly polarized slot antenna that rotates with time, on which an opening composed of a dielectric layer, an upper main conductor layer, a lower main conductor layer, a through conductor group, and a sub conductor layer is formed. Forming a cylindrical spatial resonator having a shape, and setting the dimensions of the spatial resonator within the above-mentioned predetermined range, the mode in which the electromagnetic wave of the high-frequency signal propagates in the dielectric layer forming the spatial resonator The loss due to reflection at the radiation interface can be reduced, and the slot and the spatial resonator can be coupled. The effect of the dimensional accuracy of the slot on the resonance frequency can be reduced. Te, the polarization in the far field of the electromagnetic wave of a high-frequency signal radiated from the opening surface may be circularly polarized.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laminated aperture antenna according to the present invention will be described below with reference to the drawings.

FIG. 1A is a plan view showing an example of an embodiment of a laminated aperture antenna according to the present invention, and FIG.
FIG. 3 is a sectional view taken along line AA ′ of FIG. In FIG. 1, 1
Is a dielectric substrate formed by laminating a plurality of dielectric layers 1a, 1b and 1c, 2 is an upper main conductor layer formed on the upper surface of the dielectric substrate 1, and 3 is a lower conductor formed on the lower surface of the dielectric substrate 1. It is a main conductor layer, and the dielectric substrate 1 is sandwiched between the two main conductor layers 2 and 3.

Reference numeral 4 denotes a cross-shaped slot formed by providing a conductor-free portion in the lower main conductor layer 3, and serves as a wave source for radiating electromagnetic waves of a high-frequency signal. Arbitrary feeding lines such as a microstrip line, a strip line, a waveguide line, and an NRD line are arranged below the cross-shaped slot 4, and are coupled to the cross-shaped slot 4 by an electromagnetic field to feed power to the antenna. Is performed.

Reference numeral 5 denotes a circular opening formed by providing a conductor-free portion in the upper main conductor layer 2. Electromagnetic waves distributed using the cross-shaped slot 4 as a wave source are radiated from the opening 5 to free space. . The lower main conductor layer 3 is formed below the dielectric substrate 1 at least in a position facing the opening 5, and the cross-shaped slot 4 is formed in a portion facing the center of the opening 5. Is formed.

Reference numeral 6 denotes a plurality of through conductors formed in the dielectric substrate 1 around the opening 5 and formed to electrically connect the upper main conductor layer 2 and the lower main conductor layer 3 at a predetermined interval. . The plurality of through conductors 6 are arranged at a repetition interval of less than half the signal wavelength of the high-frequency signal. The repetition interval is not necessarily limited to a constant value, and may be set by combining various values at less than half the signal wavelength.

7 is an upper main conductor layer 2 and a lower main conductor layer 3
The sub-conductor layer is formed between the dielectric layers 1a to 1c in parallel to the substrate and electrically connects the plurality of through conductors 6 between the dielectric layers 1a to 1c. The sub-conductor layer 7 forms an opening having substantially the same shape as the opening 5, and is formed as a single layer or a plurality of layers as necessary, and forms an antenna conductor wall in the dielectric substrate 1 together with the plurality of through conductors 6. . A space surrounded by the upper main conductor layer 2, the lower main conductor layer 3, and the antenna conductor wall including the plurality of through conductors 6 and the sub-conductor layers 7 connects to the cross-shaped slot 4 in the dielectric substrate 1. To form a cylindrical spatial resonator.

FIG. 2 is a perspective view showing a simplified structure of the laminated aperture antenna of the present invention shown in FIG. FIG.
Are denoted by the same reference numerals.

As shown in FIG. 2, the through conductor 6 formed in the dielectric substrate 1 around the opening 5 of the upper main conductor layer 2
And the sub-conductor layers 7 are arranged in a lattice pattern, thereby forming a conductor wall constituting a columnar spatial resonator, whereby the electric wall surrounds the cross-shaped slot 4 and the dielectric substrate 1 is formed. Is placed within. The upper main conductor layer 2 having the opening 5, the lower main conductor layer 3 having the cross-shaped slot 4, and the antenna conductor wall formed around the opening 5 by the plurality of through conductors 6 and the sub-conductor layers 7. A space resonator is formed by the enclosed cylindrical space, thereby forming a laminated aperture antenna.

Then, a cross-shaped slot 4 is formed by a feed line.
The electromagnetic wave of the high-frequency signal radiated to the opening 5 side is not propagated between the pair of main conductor layers 2 and 3 outside the space due to the presence of the cylindrical spatial resonator. Radiated from the part 5 to free space.

At this time, the lowest-order coupling mode of the cross-shaped slot 4 and the spatial resonator is such that the antenna conductor wall surrounds the cross-shaped slot 4 in a circular shape as shown in FIGS. In the space, a mode similar to the resonance mode (TE111) of the 1/4 dielectric cylinder resonator is generated,
The lowest order resonance frequency of the mode is given by the following equation.

F = 300 / √ε _r × √ [｛(1.841 / a)
/ 2π｝ ² + ｛1 / (4 × b)｝ ² ] f: resonance frequency (GHz) a: space resonator diameter (mm) b: space resonator height (mm) ε _r : relative permittivity (-) However, since power is supplied to the cylindrical spatial resonator by the cross-shaped slot 4, if the slot length is close to the resonance length, the resonance frequency is also affected by this slot length.

The electric field vector generated in this mode is shown in FIG. 3A together with the schematic configuration of the laminated aperture antenna.
To (c). 3A is a schematic configuration diagram of a stacked aperture antenna, FIG. 3B is a cross-sectional view showing electric and magnetic field vectors at section A, and FIG. 3C is a cross-sectional view showing electric and magnetic field vectors at section B. It is. In FIG. 3, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals. 8, the dashed line and arrow indicated by 10 indicate the magnetic field vector, the solid line and arrow indicated by 11 indicate the electric field vector, and two of the symbols The heavy circles indicate upwards perpendicular to the paper.

[0023] Figure 3 when the similar mode occurs TE111, for example, the b of the dimension of the spatial resonator λ _0/4,
The a corresponds to the case of the lambda _0, slot length is lambda ₀
/ 2. Therefore, the combined magnetic current of the slot becomes as shown by the outline arrow 9 and the TE111 of the resonator
It is coupled with the magnetic field vector 10 of the mode.

[0024] In the stacked aperture antenna of the present invention to emit circularly polarized wave of the high frequency signal, the thickness of the space resonator, lambda for the signal wavelength lambda ₀ of the RF signal _0/8
To [lambda] ₀ / and sets in the second range, the diameter of the opening 5 which cross-shaped slot 4 is formed at the center lambda _0/2 to 3
set within the range of λ _0/2, the slot length is λ ₀ / 4~λ
Two ₀ slots are crossed and combined to form a cross.

[0025] Here, lambda a thickness that is, the thickness of the dielectric substrate 1 of the spatial resonator for the signal wavelength lambda ₀ of the RF signal ₀
/ 8～Ramuda to set within _0/2 range, the thickness is λ
₀ / less than 8 if there is a tendency to reduce the effect as the matching layer to prevent reflection at the interface between air and the dielectric, lambda _0/2
This is because there is a tendency to be the same when the value exceeds.

Further, to set the diameter of the opening 5 which cross-shaped slot 4 is formed at the center in the range of λ ₀ / 2~3λ _0/2 relative to the signal wavelength lambda ₀ of the high frequency signal, a desired This is for obtaining the resonance frequency of

[0027] In addition, the length of the cross-shaped slot 4 λ _0/4
To set in the range of ~3λ _0/4, the slot lambda ₀
In the case of the present invention, since a spatial resonator is provided on the slot, the dimension for resonating at a desired frequency is different from the case of a single slot, λ ₀ / 4 is because the range of ~3λ _0/4.

The dielectric substrate 1 in the above embodiment can be formed into a sheet having an appropriate thickness. The dielectric substrate 1 includes an upper main conductor layer 2 such as a metallized layer, a lower main conductor layer 3 and a sub conductor layer 7. Any dielectric material that can form a conductor layer, can form a through conductor 6 such as a via conductor or a through-hole conductor, and can be closely adhered and laminated to each other can be used. For example, various ceramics, glass ceramics, resins, or resin and ceramic powder And a mixture thereof.

In order to reduce the transmission loss of the high-frequency signal as much as possible, the dielectric loss of the dielectric material is preferably small, and it is desirable that the frequency of the high-frequency signal used is 0.001 or less. Further, the metallized layer formed on the dielectric substrate 1 or the dielectric layers 1a to 1c to be the upper main conductor layer 2, the lower main conductor layer 3, the sub conductor layer 7, and the like may be formed of a low resistance conductor. Desirably, specifically, at least one of gold, silver, and copper is preferably used as a main component.

[0030]

Next, a specific example of a laminated aperture antenna according to the present invention will be described with reference to a schematic perspective view shown in FIG.

In FIG. 4, reference numeral 12 denotes a plurality of dielectric layers 12a to 12a.
A dielectric substrate formed by laminating 12c, 13 is an upper main conductor layer formed on the upper surface of the dielectric substrate 12, 14 is a lower main conductor layer formed below the dielectric substrate 12, and 15 is a lower main conductor layer Reference numeral 16 denotes a cross-shaped slot, reference numeral 16 denotes a circular opening formed in the upper main conductor layer having a diameter a, and cross-shaped slot 15 denotes an opening.
It is formed on the lower main conductor layer 14 corresponding to the central portion of 16. Reference numeral 17 denotes a plurality of through conductors formed in the dielectric substrate 12 around the opening 16, and reference numeral 18 denotes a sub-conductor layer. This upper main conductor layer
13, the lower main conductor layer 14, the plurality of through conductors 17, and the sub conductor layer
A space surrounded by the antenna conductor wall made of 18 forms a cylindrical spatial resonator having a diameter a × thickness b and connected to the cross-shaped slot 15 in the dielectric substrate 12.

The space resonator has a cross-shaped slot 15.
As a power supply line for supplying power from the antenna, a dielectric waveguide line 23 proposed by the present inventors in Japanese Patent Application Laid-Open No. 10-75108 is used. This dielectric waveguide line 23 is
Is the upper main conductor layer, and the lower part is a plurality of dielectric layers.
The dielectric substrate 19, which is formed by laminating 19a to 19c, the lower main conductor layer 20, and the upper and lower main conductor layers 14 and 20 are electrically connected with a predetermined width at a repetition interval of less than half of a high-frequency signal. And two sub-conductor layers 22 formed in parallel with the upper and lower main conductor layers 14 and 20 and electrically connected to the through conductor group 21. A high-frequency signal is transmitted by a region surrounded by the layers 14 and 20, the two rows of through conductor groups 21, and the sub-conductor layers 22.

With respect to the laminated aperture antenna of the present invention having such a configuration, the dimensions of the columnar spatial resonator are a = 0.95λ ₀ , b = 0.25λ ₀ , and the cross-shaped slot 15
Combined slot lengths by crossing two slots 0.45λ _0, 85deg and 95 the included angle of the two slots
deg. Here, λ ₀ is the signal wavelength of the high-frequency signal in the dielectric substrate. The dimensions of the dielectric waveguide line 23 are such that the transmission loss is minimized at the signal frequency.

FIG. 5 (a) shows a crossing angle of the slot of the cross-shaped slot 15 in the direction parallel to the tube axis of the dielectric waveguide line 23 of 85.
The radiation pattern from the opening surface of the sample in deg is shown by a diagram. The figure is a polar coordinate display, the opening plane is located at the center of the figure, and the value in the circumferential direction is such that the front of the opening plane is at an angle of 0 de.
g indicates the angle, and the value in the radial direction indicates the intensity of the electric field. In the characteristic curve, the solid line shows the radiation pattern on the long axis (0 deg), and the broken line shows the radiation pattern on the short axis (90 deg). FIG. 5B is a diagram illustrating frequency characteristics of the axial ratio.

As can be seen from the results shown in FIG.
The main beam in the far field of the electromagnetic wave radiated from the aperture surface is radiated in the front direction of the aperture surface and has a long axis (0 de).
g) and the radiation pattern in the short axis (90 deg) are almost coincident. Also, as can be seen from the results shown in FIG. 5B, the axial ratio was within 3 dB in the range of about 1.2 GHz, and it was confirmed that circularly polarized waves were radiated.

Also, it was confirmed that a good circularly polarized wave was radiated in the sample in which the angle between the slots of the cross-shaped slot 15 was 95 deg.

It should be noted that the present invention is not limited to the above-described embodiments, and that various changes and improvements can be made without departing from the scope of the present invention.

For example, in the above-described example, the spatial resonator has a cylindrical shape. However, the same effect can be obtained by changing the sectional size, height, slot size, etc. of the rectangular shape into a rectangular shape, for example. .

[0039]

As described in detail above, according to the laminated aperture antenna of the present invention, an upper portion having a circular opening formed on the upper surface of a dielectric substrate formed by laminating a plurality of dielectric layers. A main conductor layer, a lower main conductor layer formed at a position facing the opening below the dielectric substrate, and an upper main conductor layer and a lower main conductor formed at predetermined intervals in the dielectric substrate around the opening. A spatial resonator surrounded by a plurality of through conductors electrically connecting the layers and an antenna conductor wall composed of a sub-conductor layer electrically connecting the plurality of through conductors between the dielectric layers is formed. Two slots for supplying a high-frequency signal are intersected and combined in a portion facing the opening of the body layer to form a cross-shaped slot in the lower main conductor layer facing the center of the opening, and a dielectric for the high-frequency signal is formed. Signal wavelength in substrate when the lambda _0, the thickness of the space resonator λ ₀ / 8~λ _0/2, the diameter of the opening λ _0/2 ~3 λ
_0/2, and the cross-shaped slot slot length λ ₀ / 4~3
lambda _0/4 of the two slots from that assumed made by intersecting in a cross shape, due to reflection by suppressing mode the dielectric layer constituting the spatial resonator electromagnetic wave of a high frequency signal propagating in the radiation surface Since the loss can be reduced and the resonance frequency can be controlled by the cross-shaped slot and the spatial resonator, even if the dimensional accuracy of the cross-shaped slot has an error of several% with respect to the slot length, it is stable. Resonance in a desired frequency band can be obtained, whereby the main beam in the far field of the electromagnetic wave of the high-frequency signal radiated from the aperture surface can be stably radiated as a circularly polarized wave.

As described above, according to the present invention, while suppressing the reflection loss at the radiation interface between the slot and the free space in the slot antenna, radiation at a desired frequency is possible even if the dimensional accuracy of the slot is about several percent. Thus, it is possible to provide a laminated aperture antenna capable of setting the main beam in the far field of the electromagnetic wave of the high-frequency signal to be circularly polarized.

[Brief description of the drawings]

FIGS. 1A and 1B are a plan view and a cross-sectional view taken along line AA ′, respectively, showing an example of an embodiment of a laminated aperture antenna according to the present invention.

FIG. 2 is a simplified perspective view of the structure of the laminated aperture antenna of the present invention shown in FIG.

FIG. 3A is a diagram illustrating a coupling mode between a spatial resonator and a slot in the laminated aperture antenna according to the present invention.
Is a schematic perspective view of a stacked aperture antenna, (b) is a cross-sectional view showing electric and magnetic field vectors in cross section A, (c)
Is a cross-sectional view showing an electric / magnetic field vector in the cross section B.

FIG. 4 is a schematic perspective view for explaining a specific example of the laminated aperture antenna of the present invention.

FIG. 5A is a diagram showing a radiation pattern from an aperture surface in a specific example of the laminated aperture antenna of the present invention;
(B) is a diagram showing frequency characteristics of an axial ratio.

[Explanation of symbols]

1, 12 ... dielectric substrate 1a-1c, 12a-12c ... dielectric layer 2, 13 ... Upper main conductor layer 3, 14 ... Lower main conductor layer 4, 15 ... Cross-shaped slot 5, 16 ...・ ・ ・ ・ ・ ・ ・ ・ ・ Opening 6,17 ・ ・ ・ ・ ・ ・ ・ Through conductor 7,18 ・ ・ ・ ・ ・ ・ Sub-conductor layer λ ₀・ ・ ・ ・ ・ ・ Signal wavelength of high frequency signal in dielectric substrate

Claims (1)

[Claims] An upper main conductor layer having a circular opening formed on an upper surface of a dielectric substrate formed by laminating a plurality of dielectric layers, and facing the opening below the dielectric substrate. A lower main conductor layer formed at a position, a plurality of through conductors formed in the dielectric substrate around the opening, and electrically connecting the upper main conductor layer and the lower main conductor layer at predetermined intervals; and Forming a spatial resonator surrounded by an antenna conductor wall composed of a sub-conductor layer electrically connecting the plurality of through conductors between the dielectric layers, and facing a center of the opening of the lower main conductor layer; A cross-shaped slot for forming a cross-shaped slot for supplying a high-frequency signal to a portion to be formed, wherein the signal wavelength of the high-frequency signal in a dielectric substrate is λ ₀ , the thickness of λ ₀ / 8~λ _0/2 The diameter of the aperture λ _0/2 ~
3 [lambda] _0/2 and then, slot length lambda ₀ the cross-shaped slot
/ 4~3λ ₀ / laminated aperture antenna which 4 slots two crossed in a cross shape, characterized in that shall composed.