JP2000082914A - Microstrip antenna, antenna device using the antenna and radio device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microstrip antenna which can simplify the constitution of a feeder circuit and also can suppress deterioration in characteristics including an axial ratio, etc. SOLUTION: A rectangular, rhombic, circular or elliptical patch electrode 12 having its symmetrical axes in the radio wave radiating or receiving X and Y axis directions is put on one of both sides of a magnetic substrate 11 which has different relative magnetic permeabilites in X and Y axis directions. A ground electrode 13 is placed on the other side of the substrate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a radio system using circularly polarized radio waves, such as satellite navigation and satellite communication,
The present invention relates to a microstrip antenna that emits or receives a circularly polarized radio wave, and an antenna device and a radio device including the microstrip antenna.

[0002]

2. Description of the Related Art In a radio system using a satellite such as satellite communication or satellite broadcasting, a radio wave transmitted toward a satellite or a radio wave transmitted from a satellite passes through the ionosphere above. When radio waves pass through the ionosphere, rotation of the plane of polarization called Faraday rotation occurs. If the direction of polarization of the arriving radio wave and the direction of polarization of the receiving antenna do not match due to the rotation of the plane of polarization, this becomes one of the causes of loss, resulting in a decrease in reception sensitivity. Circular polarization means that the plane of polarization rotates with time, and even if Faraday rotation occurs in the ionosphere, its effect can be ignored. Therefore, a circularly polarized wave is generally used in a radio system using this type of satellite.

A microstrip antenna is known as one of the antennas for generating or receiving circularly polarized waves. Microstrip antennas have been used as on-board antennas for moving objects such as aircraft and vehicles, and more recently, using low-orbit satellites because of their thinness and ease of mass production due to printing technology. Attention has been paid to antennas for terminal devices and the like of worldwide mobile telephone systems.

FIG. 13 is a perspective view showing a conventional microstrip antenna. The conventional microstrip antenna 100 has a dielectric substrate 1 that is sufficiently thin compared to the wavelength.
01 is provided with a patch electrode 102 having a square shape, for example, and a ground electrode 103 is formed on a surface opposite to the surface on which the patch electrode 102 is provided, and a potential difference is applied between these two electrodes to operate as an antenna. . Generally, in order to generate circularly polarized waves, two spatially orthogonal wave sources (current and magnetic current) having an equal amplitude of 90 degrees and a phase difference are required. In the microstrip antenna shown in FIG. 13, the two feeding points 104a and 104b provided at positions spatially orthogonal to each other on the patch electrode 102 provide two signals having a phase difference of 90 degrees with equal amplitude. It can be operated as a polarization antenna. A microstrip antenna that performs a circular polarization operation by such a feeding method is called an orthogonal two-point feeding type circularly polarized microstrip antenna or the like.

FIG. 14 shows another conventional microstrip antenna. The microstrip antenna 200 shown in FIG. 14 is similar to the conventional example shown in FIG.
01, for example, a substantially square patch electrode 20
2 and a ground electrode 203 is formed on the surface opposite to the surface on which the patch electrode 202 is provided. However, in the conventional example of FIG. 14, by providing the patch electrode 202 with degenerate separation elements 205a and 205b such as cutouts, power is supplied to only one feeding point 204 on the patch electrode, so that the frequency becomes close. Then, two modes having a 90-degree phase difference that are spatially orthogonal to each other are generated to perform circular polarization operation.
Such a microstrip antenna is called a one-point feeding type circularly polarized microstrip antenna or the like.

[Problems to be solved by the invention]

However, when a conventional microstrip antenna using a dielectric substrate as described above is operated in circular polarization, the two-point feeding type circularly polarized microstrip antenna 100 shown in FIG. In order to obtain two signals having a degree phase difference, for example, a circuit component called a 90 degree hybrid, which is not shown, is required, and there has been a problem that the configuration of the power supply circuit is complicated. In addition, this type of antenna is often used as an array antenna, and there has been a problem that a feeder circuit becomes complicated when configuring an array antenna.

In the single-point feed circularly polarized microstrip antenna 200 shown in FIG. 14, the frequency band for circularly polarized light operation is very narrow, and objects around the antenna, such as a human body and a housing, are placed. Is present, the operating frequency of the antenna (referred to as a circularly polarized wave generation frequency) changes, and performance such as an axial ratio at a desired frequency deteriorates. Since the shape and position of the degenerate separation element are fixed,
Circular polarization generation frequency cannot be controlled or adjusted, and as a result,
There is a problem that characteristic deterioration cannot be suppressed. Here, the axial ratio is the ratio between the major axis and the minor axis of the polarization ellipse, which is a locus drawn by the electric field vector. The axial ratio of a circularly polarized antenna that radiates or receives an ideal circularly polarized wave is 1 ( 0 dB)
Becomes

[0008] The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a microstrip antenna capable of simplifying the configuration of a feed circuit and suppressing deterioration of characteristics such as an axial ratio. Another object of the present invention is to provide an antenna device and a wireless device including such a microstrip antenna.

[Means for Solving the Problems]

In order to achieve the above object, a microstrip antenna according to the present invention is provided on a surface of a magnetic substrate having different relative magnetic permeability in the X-axis direction and the Y-axis direction. A rectangular shape having a symmetry axis in the Y-axis direction,
A diamond-shaped, circular or elliptical patch electrode is provided, and a ground electrode is provided on the other surface of the magnetic substrate. In the microstrip antenna having the above-described configuration, the magnetic substrate having the axial anisotropy in which the relative magnetic permeability in the X-axis direction and the relative magnetic permeability in the Y-axis direction is different is that the relative magnetic permeability in one direction is different from that in the other direction. When it has a different value, the propagation constant in the direction having the different relative magnetic permeability is different from the propagation constant in the other direction, thereby separating the two degenerate orthogonal modes and generating a circularly polarized wave. This is because it can be done. According to the microstrip antenna of the present invention, with the above-described configuration, circular polarization can be generated without providing a cutout or the like as a degenerate separation element in the patch electrode.

In the microstrip antenna according to the present invention, it is preferable that the antenna be circularly polarized with only one feeding point on the patch electrode, since a simple feeding circuit can be formed.

Further, in the microstrip antenna of the present invention, it is preferable that the patch electrode is covered with a protective layer from the viewpoint of protecting the patch electrode.
Furthermore, the fact that this protective layer is made of a dielectric or non-conductive magnetic material is more effective than the microstrip antenna without this dielectric / magnetic material protective layer, in addition to the magnetic permeability of the magnetic substrate and the protective layer dielectric. The dielectric constant of the protective layer and the magnetic permeability of the magnetic material of the protective layer act to shorten the resonance wavelength, so that the size of the substrate in the X-Y direction can be reduced, so that the size of the microstrip antenna can be reduced.

An antenna device and a radio device according to the present invention include the microstrip antenna according to the present invention. According to the antenna device and the wireless device of the present invention, the provision of the microstrip antenna of the present invention makes it possible to simplify the configuration of a feed circuit for operating the antenna in circularly polarized waves, and to improve the axial ratio and the like. Thus, it is possible to suppress the deterioration of the characteristics at the time of the circularly polarized wave operation and achieve high performance.

The material constituting the magnetic substrate used in the present invention is such that the microstrip antenna of the present invention has a frequency of several hundred MHz.
When provided in an antenna device or a radio device used in the following frequency bands, there is no particular limitation as long as it is a magnetic material that can be used for high frequencies, but an antenna device or a radio device used in a high frequency band of several hundred MHz or more In the case of being prepared for, the decrease in magnetic permeability and the increase in loss at high frequencies are suppressed and the high frequency characteristics are excellent,
It is preferable to use a high frequency composite material.

As the high frequency composite material, AM-
D (where A represents at least one element selected from the group consisting of Fe, Co, and Ni or a mixture thereof;
Are Hf, Zr, W, Ti, V, Nb, Mo, Cr, M
g, Mn, Al, Si, Ca, Sr, Ba, Cu, G
a, As, Se, Zn, Cd, In, Sn, Sb, T
e, Pb, Bi, at least one element selected from the group of rare earth elements or a mixture thereof, and D represents O,
It represents at least one element selected from the group consisting of C, N and B or a mixture thereof. ) Based soft magnetic alloy powder and a synthetic resin such as polytetrafluoroethyne,
Those having soft magnetism and dielectric properties can be used.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIGS. 1 and 2,
The microstrip antenna 10 of the first embodiment includes:
A magnetic substrate 11 having axial anisotropy, a rectangular patch electrode 12 provided on one surface of the magnetic substrate,
It is roughly constituted by a ground electrode 13 provided on the surface opposite to the surface on which the patch electrode 12 is provided, and only one feeding point A is provided on the patch electrode 12.

The patch electrode 12 is a square whose one side is an electric length of λe / 2.
Power supply pin 1 penetrating magnetic substrate 11 and ground electrode 13
Power is supplied from the rear through the power supply 4. Here, λe represents the effective wavelength of the radio wave having the circularly polarized wave generation frequency fo inside the antenna. The magnetic substrate 11 has uniaxial anisotropy in the X-axis direction, and the value of the relative magnetic permeability in the X-axis direction is larger than the value of the relative magnetic permeability in other directions. The values of the relative magnetic permeability in the anisotropic axis direction and other directions are not particularly limited.
Since two orthogonal wave sources are required, it is desirable that the relative magnetic permeability in the anisotropic axis direction and other directions be relatively close values. Further, the circularly polarized wave generation frequency is determined by the ratio between the value of the relative magnetic permeability in the anisotropic axis direction and the value of the relative magnetic permeability in other directions. The feeding point A is provided at a position where circular polarization is generated at a desired frequency and impedance matching is improved. As a material forming the patch electrode 12 and the ground electrode 13, a good conductive metal such as Cu, Al, or Ag is used.

As a specific example of the microstrip antenna of the first embodiment, the size (length × width × height) of the microstrip antenna 10 is 50 mm × 50 mm.
The size is about 3 mm, and the operating frequency (circular polarization generation frequency) is about 3 GHz. As a specific example of the dimensions of each part of the antenna, the size of the patch electrode 12 is 30 mm ×
At 30 mm, the position of the feeding point A is 3 mm in the + X-axis direction and 5.5 mm in the -Y-axis direction from the central portion D of the patch electrode.
It is an offset point. The magnetic substrate 11 is made of a high frequency composite material, and has a size (length × width × height) of 50 mm × 50 mm × 3 mm and a relative dielectric constant of 2.
6. The relative magnetic permeability is 1.1 only in the X-axis direction and 1 in other directions.

The power is supplied, for example, via a connector (not shown) having an outer conductor provided outside the inner conductor via a dielectric. That is, the internal conductor of the connector is used as the power supply pin 14 to insulate the power supply pin 14 from contact with the ground electrode 13, to lead out to the patch electrode 12 through the magnetic substrate 11 and the ground electrode 13, and to feed the tip to the power supply point A.
Is connected to the patch electrode 12 by soldering or the like. The thickness of each of the patch electrode 12 and the ground electrode 13 formed on the surface of the magnetic substrate 10 is 100 μm.
It is.

Next, a second embodiment of the microstrip antenna of the present invention will be described with reference to FIGS.
The microstrip antenna of the second embodiment is
Since the shape of the patch electrode 12 of the microstrip antenna 10 of the first embodiment shown in FIGS. 1 and 2 is rhombic, and other members except for the rhombic patch electrode are the same, FIGS. The same members as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIGS. 3 and 4, the patch electrode 22 of the microstrip antenna 20 has a rhombic shape, and two diagonal lines thereof coincide with the X-axis direction and the Y-axis direction, respectively. The shape of the patch electrode 22 is determined by the length of two diagonal lines,
Each length is set to a desired value in consideration of the ratio of the magnetic permeability of the magnetic substrate 13 in the X-axis direction and the Y-axis direction. According to the microstrip antenna of the second embodiment, with the above-described configuration, the same operation and effect as those of the first embodiment can be achieved.

A third embodiment of the microstrip antenna according to the present invention will be described with reference to FIGS. The microstrip antenna of the third embodiment is shown in FIG.
1 and FIG. 2 since the shape of the patch electrode 12 of the microstrip antenna 10 of the first embodiment shown in FIG. 2 is circular, and the other members except for the circular patch electrode are the same. The same reference numerals are given to the same members as those shown in (1), and their description is omitted. As shown in FIGS. 5 and 6, the patch electrode 32 of the microstrip antenna 30 has a circular shape, and the diameters corresponding to the X-axis direction and the Y-axis direction can be regarded as the axes of symmetry.
According to the microstrip antenna of the third embodiment, with the above-described configuration, the same operation and effect as those of the first embodiment can be achieved.

A fourth embodiment of the microstrip antenna according to the present invention will be described with reference to FIGS. The microstrip antenna according to the fourth embodiment is shown in FIG.
1 and FIG. 2 because the shape of the patch electrode 12 of the microstrip antenna 10 of the first embodiment shown in FIG. 2 is made elliptical, and the other members except for the elliptical patch electrode are the same. The same reference numerals are given to the same members as those shown in (1), and their description is omitted. In the microstrip antenna 40, as shown in FIGS. 7 and 8, the patch electrode 42 has an elliptical shape, and two symmetrical axes including the major axis and the minor axis coincide with the X-axis direction and the Y-axis direction. . The shape of the patch electrode 42 is determined by the lengths of the long axis and the short axis, and each length is a desired value in consideration of the ratio of the magnetic permeability of the magnetic substrate 13 in the X-axis direction and the Y-axis direction. Shall be. According to the microstrip antenna of the fourth embodiment, with the above-described configuration, the same operation and effect as those of the first embodiment can be achieved.

The microstrip antenna 50 according to the fifth embodiment of the present invention shown in FIG. 9 has a protective layer 51 on the upper surface of the microstrip antenna 10 shown in FIGS.
The same members as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. That is, the microstrip antenna 50 has a protective layer 51 made of a dielectric or non-conductive magnetic material that covers the patch electrodes 12 and the magnetic substrate 11 on the magnetic substrate 11 on which the patch electrodes 12 are formed. Provided. As a material forming the protective layer 51, a high-frequency low-loss dielectric material such as polytetrafluoroethylene or a magnetic material similar to the magnetic substrate 11 is used.

According to the microstrip antenna of the fifth embodiment, in particular, the protection layer 51 is provided on the magnetic substrate 11 on which the patch electrode 12 is directly formed, thereby protecting the patch electrode 12. In addition to the above, an effect of shortening the wavelength due to the dielectric constant and / or magnetic permeability of the protective layer 51 is added, so that further miniaturization is possible. In this embodiment, the case where the shape of the patch electrode 12 is square is shown, but the shape of the patch electrode is not limited to square, but is rectangular, rhombus shown in FIGS. 3 and 4, FIG. Each of the circular shape shown in FIG. 6 and the elliptical shape shown in FIGS. 7 and 8 may be used.

In the above embodiments, the case where the shapes of the magnetic substrate 11 and the ground electrode 13 are square has been described. However, these shapes are not limited to square, and may be, for example, circular. .

Next, an embodiment of an antenna device having the microstrip antenna of the present invention will be described. FIG. 10 shows a satellite navigation device G as an application example of the microstrip antenna of the present invention to an antenna device.
PS antenna module (hereinafter, antenna module)
3A and 3B are an external view and a cross-sectional view showing the configuration of FIG. As shown in FIG. 10A, only the radome 61 and the coaxial cable 62 can be seen from the external structure of the antenna module 60. The antenna module 60 is installed, for example, on the roof of a vehicle, and the coaxial cable 62 is connected to a satellite navigation receiver (not shown).

The antenna module will be described in more detail. As shown in FIG. 10B, a coaxial cable 62 is connected to the antenna circuit means and covered by an upper case 61a and a lower case 61b forming a radome 61. Have been. Both upper case 61a and lower case 61b are AB
It is made of resin such as S, and is fastened with screws 63. The antenna circuit means is the microstrip antenna 1 of the present invention.
0, 20, 30, 40, etc., and a high-frequency circuit section 70 such as a low-noise amplifier. Hereinafter, the microstrip antenna 10 shown in FIGS. 1 and 2 will be described as a microstrip antenna by way of a representative example.

The high-frequency circuit section 70 includes a printed circuit board 71 and electronic components 72 such as transistors, ICs, capacitors, inductors, and resistors, and is covered by a shield case 73 for preventing external noise. The feed point A of the microstrip antenna 10 and the terminal B of the high-frequency circuit unit 70 are connected by a feed pin 74 by soldering. In addition, the coaxial cable 62 is connected to the terminal C of the high-frequency circuit unit 70.

With the above configuration, the radio wave from the GPS satellite received by the microstrip antenna 10 is amplified by the high frequency circuit 70 and
2, the data is supplied to a satellite navigation receiver (not shown).

Next, an embodiment of a wireless device having the microstrip antenna of the present invention will be described. FIG. 11 shows a microstrip antenna 1 of the present invention.
FIG. 3 is a plan view showing a configuration of a circuit board block of a transmitting / receiving device of a mobile phone system using a satellite as an example in which 0, 20, 30, 40, 50, and the like are applied to a wireless device. Hereinafter, the microstrip antenna 10 shown in FIGS. 1 and 2 will be described as a microstrip antenna by way of a representative example. In this circuit board block, as shown in FIG. 11, a microstrip antenna 10, a high-frequency circuit section 90, a detector 87, and other electronic circuits 95 are arranged on a circuit board 80, and these circuit sections are connected to a circuit board 8
0 are connected to each other by a wiring pattern 99 formed on the back surface and other wiring patterns not shown.

As shown in FIG. 12, the high frequency circuit section 90 includes a transmission / reception separation circuit 81, a low noise amplifier 82, a first mixer 83, a first band-pass filter 84, a second mixer 85, A reception system circuit including the second band-pass filter 86 and the first oscillator 88, and a transmission system circuit including the power amplifier 89, the third mixer 91, the modulator 92, the second oscillator 92, and the synthesizer 93 It is configured. The microstrip antenna 10 and the high-frequency circuit unit 90
The second band-pass filter 86 and the detector 87 are connected by a wiring pattern 99, and are connected by another wiring pattern.

A series of operations at the time of reception of the transmitting / receiving apparatus of this embodiment will be described. At the time of reception, a reception signal received by the microstrip antenna 10 of the present invention reaches a low noise amplifier 82 via a transmission / reception separation circuit 81 for separating a transmission signal and a reception signal, where the signal is amplified to a desired level. Is done. Then, the received signal amplified by the low noise amplifier 82 is frequency-converted to an intermediate frequency by the first mixer 83 using the output signal of the synthesizer 93. The signal converted by the first mixer 83 passes through a first band-pass filter 84, and is passed through a first mixer 88 by a second mixer 85.
Is further frequency-converted using the output signal of. The signal frequency-converted by the second mixer 85 passes through a second band-pass filter 86 and reaches a detector 87, where it is detected and information is extracted.

At the time of transmission, the carrier signal output from the second oscillator 93 is modulated by the modulator 92. The signal modulated by the modulator 92 is frequency-converted by the third mixer 91 using the output signal of the synthesizer 94, amplified to a desired level by the power amplifier 89, and then passed through the transmission / reception separation circuit 81. Then, the light is radiated from the microstrip antenna 10 of the present invention. In the above-described embodiment of the wireless device, the configuration has been described in which the microstrip antenna 10 is shared for transmission and reception.
It may be configured to connect to each of the transmitting device and the receiving device.

[0033]

As described above, according to the microstrip antenna of the present invention, the above-described configuration simplifies the configuration of the power supply circuit required for circularly polarized wave excitation. Further, according to the antenna device and the wireless device of the present invention, the provision of the microstrip antenna of the present invention simplifies the configuration of the feeder circuit for operating the antenna in a circularly polarized wave operation, and makes the configuration of a circularly polarized wave such as an axial ratio. It is possible to suppress characteristic deterioration during operation, and to achieve higher performance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a microstrip antenna of the present invention.

FIG. 2 is a plan view of the microstrip antenna shown in FIG.

FIG. 3 is a perspective view showing a microstrip antenna according to a second embodiment of the present invention.

FIG. 4 is a plan view of the microstrip antenna shown in FIG.

FIG. 5 is a perspective view showing a third embodiment of the microstrip antenna of the present invention.

6 is a plan view of the microstrip antenna shown in FIG.

FIG. 7 is a perspective view showing a fourth embodiment of the microstrip antenna of the present invention.

FIG. 8 is a plan view of the microstrip antenna shown in FIG.

FIG. 9 is a perspective view showing a fifth embodiment of the microstrip antenna of the present invention.

10A and 10B are diagrams illustrating an embodiment of an antenna device including the microstrip antenna illustrated in FIG. 1; FIG. 10A is a perspective view, and FIG.
It is sectional drawing along the b-Xb line.

11 is a plan view illustrating an embodiment of a wireless device including the microstrip antenna illustrated in FIG.

FIG. 12 is a block diagram of the embodiment of the wireless device shown in FIG. 11;

FIG. 13 is a perspective view showing a conventional microstrip antenna.

FIG. 14 is a perspective view showing another conventional microstrip antenna.

[Explanation of symbols]

10, 20, 30, 40, 50 Microstrip antenna 11 Magnetic substrate 12, 22, 32, 42 Patch electrode 13 Ground electrode 14, 74 Power supply pin 51 Protective layer 60 Antenna module 61 Radome 62 Coaxial cable 70 High-frequency circuit section 80 Circuit Substrate 81 Transmission / reception separation circuit 84 First bandpass filter 86 Second bandpass filter 87 Detector 92 Modulator 93 Second oscillator A Feeding point B, C Connection terminal D Central part of patch electrode

Claims (5)

[Claims] An X-ray radiation or reception radio wave is provided on one surface of a magnetic substrate having different relative magnetic permeability in the X-axis direction and the Y-axis direction.
A rectangular shape, a rhombus shape having an axis of symmetry in the axial direction and the Y-axis direction,
A microstrip antenna comprising: a circular or elliptical patch electrode; and a ground electrode on the other surface of the magnetic substrate. 2. The microstrip antenna according to claim 1, wherein one excitation feeding point for exciting the patch electrode is provided. 3. The microstrip antenna according to claim 1, wherein a dielectric layer for protecting the patch electrode or a protective layer made of a non-conductive magnetic material is provided on the patch electrode. 4. An antenna device comprising the microstrip antenna according to claim 1. Description: 5. A wireless device comprising the microstrip antenna according to claim 1. Description: