WO2007122723A1

WO2007122723A1 - Antenna device

Info

Publication number: WO2007122723A1
Application number: PCT/JP2006/308411
Authority: WO
Inventors: Yoko Koga; Kazushi Nishizawa; Yasuhiko Urata; Tamotsu Nishino; Hiroaki Miyashita; Shigeru Makino
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2006-04-21
Filing date: 2006-04-21
Publication date: 2007-11-01
Also published as: JPWO2007122723A1; JP4527167B2

Abstract

Provided is an antenna device capable of reducing the influences of a bias line in a plane antenna. The antenna device comprises a dielectric substrate, an earthing member formed on the back of the dielectric substrate, a first conductor of a rectangular annulus shape formed on the surface of the dielectric substrate, a second conductor of a rectangular shape so formed on the inner side of the first conductor as to form a closed annular slot, a switch so arranged diagonally of the first and second conductors as to joint the first conductor and the second conductor, a bias line wired on the plane common to the first conductor and the second conductor for controlling the switch, and an open leading end stub connected with the bias line and having a length of a quarter of the wavelength. A wider slot than the width of the bias line is formed in the vicinity of the corner of the first conductor of the rectangular shape. The bias line is wired in a bridge girder shape over the first conductor at the portion where the first conductor and the slot cross, and a feeding point is arranged at the center of the second conductor.

Description

Specification

Antenna device

Technical field

[0001] The present invention relates to an antenna device in which a planar antenna having a polarization switching function with reduced influence of a bias line is realized by loading a switch.

Background art

[0002] With the recent development of communication systems and radar systems in the high frequency band, there is an increasing demand for smaller and higher performance antennas. High performance here means that it can operate in a wide frequency band, has resonance characteristics at multiple frequencies, left-handed rotation, right-handed rotation, vertical rotation, horizontal Z, or those

As an example, it has four types of polarization switching function 'or sharing function. In addition, downsizing of antennas leads to downsizing of radar communication equipment and reduction of power consumption.

[0003] A conventional antenna device for switching the polarization will be described with reference to FIG. 8 (see, for example, Non-Patent Document 1). FIG. 8 (a) is a plan view of a conventional antenna device, and FIG. 8 (b) is a cross-sectional view of the central portion of (a). This antenna device is loaded with a cross-shaped slot 23 inside a microstrip antenna 21 and a star-shaped four PIN diodes 22 in the center, and switches the switch to change the direction of the current flowing on the antenna. The vertical Z horizontal polarization is switched. In this antenna device, the diode control device 27 including the bias line is supplied by a coaxial line from a feeding point 24 near the center of the force notch antenna provided under the antenna substrate (dielectric substrate) 25. There is concern that the noise wire will affect the antenna characteristics. A ground conductor 26 is provided on the back surface of the dielectric substrate 25.

[0004] When a planar antenna has a polarization switching function, it is possible to provide slots and switches in the antenna pattern as in the antenna mentioned above as an example, and change the current flow on the antenna by switching the switches. It is valid. However, as described above, the wiring of the bias line below the substrate affects the characteristics when feeding from the center. To avoid this effect, when the bias line is wired on the same plane as the antenna, the antenna A part intersecting the pattern and the bias line is generated, which becomes a problem when the bias line is formed on the substrate by patterning.

[0005] Furthermore, when a bias line is wired on the same plane as the antenna, an RF signal propagates through the bias line and affects the antenna characteristics such as resonance frequency and radiation pattern deviation. There was a need.

[0006] Non-patent document 1: Eisuke Nishiyama, Koichi Takenaka, Masayoshi Aikawa "Microstrip antenna with orthogonal polarization function" IEICE Transactions B, Vol. J85—B, No. 9, pp. 1519

— 1525, September 2002.

Disclosure of the invention

Problems to be solved by the invention

[0007] As described above, in the conventional antenna device, there is a concern that the bias line may affect the antenna characteristics when power is supplied from the vicinity of the center of the patch antenna through the coaxial line. When wiring on the same plane as the antenna, there will be a part that intersects the antenna pattern and the bias line, which will be a problem when creating the noise line on the substrate with patterning, and further, on the same plane as the antenna. When the bias line is wired to the antenna, the RF signal propagates through the noise line and affects the antenna characteristics, so there is a problem that it is necessary to take some measures.

[0008] The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an antenna device capable of reducing the influence of a bias line in a flat antenna. is there.

Means for solving the problem

The antenna device according to the present invention is a planar rectangular patch antenna, and includes a dielectric substrate, a ground conductor formed on a back surface of the dielectric substrate, and a rectangle formed on the surface of the dielectric substrate. An annular first conductor, and a rectangular second conductor formed inside the first conductor so as to form a surface of the dielectric substrate and a closed annular first slot; A switch disposed on a diagonal line of the rectangular first and second conductors so as to couple the first conductor and the second conductor, and on the same plane as the first and second conductors; A bias line that is wired and controls the switch, and is connected to the bias line and has a wavelength of 1 A tip open stub having a length of Z4, and a second slot wider than the width of the noise line is formed below the bias line near the corner of the rectangular first conductor, The bias line is wired so as to bridge the first conductor at the portion where the first conductor and the second slot intersect, and the feeding point is arranged at the center of the second conductor. It is what has been.

The invention's effect

[0010] The antenna device according to the present invention has the effect of reducing the influence of the bias line in the planar antenna.

Brief Description of Drawings

FIG. 1 is a perspective view showing a configuration of an antenna apparatus according to Embodiment 1 of the present invention.

FIG. 2 is an enlarged view showing a cross section of a region 9 in FIG.

FIG. 3 is a perspective view showing a configuration of an antenna apparatus according to Embodiment 2 of the present invention.

FIG. 4 is a diagram showing the reflection characteristics of the antenna device according to Example 2 of the present invention.

FIG. 5 is a diagram showing radiation characteristics of the antenna device according to Example 2 of the present invention.

FIG. 6 is a perspective view showing a configuration of an antenna apparatus according to Embodiment 3 of the present invention.

FIG. 7 is a diagram showing another configuration of the antenna apparatus according to Embodiment 3 of the present invention.

FIG. 8 is a diagram showing a configuration of a conventional antenna device.

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] Examples 1 to 3 of the present invention will be described below.

Example 1

An antenna device according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing a configuration of an antenna device (planar antenna) according to Embodiment 1 of the present invention. FIG. 2 is an enlarged view showing a cross section of the region 9 in FIG. In the following, in each figure, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, an antenna device (planar antenna) according to Example 1 is formed on a dielectric substrate 1, a ground conductor 2 formed on the back surface of the dielectric substrate 1, and a surface of the dielectric substrate 1. Formed on the inside of the first conductor 3 of the rectangular annular shape and the first conductor 3 on the surface of the dielectric substrate 1 Second rectangular conductor 4, rectangular annular slot 5, nose wire 6 (6a, 6b, 6c, 6e), open-ended stub 7 connected to bias wire 6 respectively, Four rectangular slots (openings) 8 provided in one conductor 3 and four switches 10 (10a, 10b, 10c, 1 Oe) are provided.

FIG. 2 shows a cross section along the bias line 6c, showing a cross section of the slot 8 portion of the first conductor 3 formed on the dielectric substrate 1, and the bias line 6c is the first conductor 3 Passed over the bridge. When the bias voltage is not applied, the switch 10 is in the OFF state, and the first conductor 3 and the second conductor 4 are not connected.

Next, the operation of the antenna device according to the first embodiment will be described with reference to the drawings.

Power feeding is performed to the center of the second conductor 4 by a coaxial line or the like. At the same time as supplying power to the second conductor 4, a bias voltage is applied to the bias line 6 to control ONZOFF of the switch 10. At this time, the switch 10 to be controlled is selected according to the desired polarization direction.

For example, in FIG. 1, when it is desired to direct the main polarization direction parallel to the vertical direction of the paper surface, a bias voltage is applied to the noisy wires 6a and 6b, and the switches 10a and 10b are turned on, that is, the switch 10a. 10b, the first conductor 3 and the second conductor 4 are connected. By doing so, the shape of the slot 5 changes, the direction of the current flowing on the first conductor 3 and the second conductor 4 changes, and the polarization can be directed in a desired direction.

Note that the sizes of the first conductor 3 and the second conductor 4 and the width of the slot 5 are optimized in advance so as to achieve matching at a desired frequency. Matching can be achieved by the interaction of the size of the first conductor 3 and the second conductor 4 and the width of the slot 5, but if matching is achieved, the resonance frequency will be reduced to the size of the first conductor 3. The degree of dependence is high.

Here, it is desirable that the slot 8 opened in the first conductor 3 has a size that does not affect the path of the current flowing on the first conductor 3 as much as possible. However, when a voltage is applied to the bias line 6, the bias line 6 passed over the first conductor 3 and the first conductor 3 form a capacitor, and electrostatic force is generated in the direction that attracts the two. Arise. This size depends on the distance between the two, the area of the opposing part, the Young's modulus of the material of the bias line 6 and the spring constant. Therefore, the width and length of the bias line 6 must be selected considering the above. Absent.

When the switch 10 is turned on, a current also flows through the second conductor 4, and an RF signal propagates to the bias line 6. Here, if there is a reflection point on the bias line 6 and the RF signal causes multiple reflections, the antenna characteristics will be affected, causing a shift in resonant frequency and an increase in cross-polarized components.

[0022] At this time, when the length of the stub 7 is λ / 4 from the open end and the stub 7 is attached to the bias line 6 at a position of λ エッジ 4 from the edge of the first conductor 3, the first conductor 3 The bias line 6 ahead of the edge of the edge can be seen at the open end, reducing the propagation of the RF signal and suppressing the above-mentioned effects. Here, the length of the stub 7 and the distance from the edge are optimized at the time of design which is not strictly λ / 4.

Example 2

An antenna apparatus according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 3 is a perspective view showing the configuration of the antenna device according to Embodiment 2 of the present invention. FIG. 4 is a diagram showing the reflection characteristics of the antenna device according to Example 2 of the present invention. Further, FIG. 5 is a diagram showing the radiation characteristics of the antenna device according to Example 2 of the present invention.

Here, the same reference numerals as those in FIG. 1 that do not require description are omitted. In FIG. 3, the conductor pattern 11 connects the first conductor 3 and the second conductor 4.

In FIG. 3, the switch 10 is controlled to be turned off by applying a bias voltage to the bias line 6 as in the first embodiment. However, since the switch 10 to be controlled when switching the polarization is one for the desired polarization direction, the wiring of the bias line 6 and the configuration of the bias circuit become easy.

[0026] Further, due to the presence of the conductor pattern 11, the potentials of the first conductor 3 and the second conductor 4 become equal. If the potential is the same, the charge accumulated in the capacitor formed by the bias line 6 and the planar antenna (first conductor 3), as shown in Fig. 2, when the switch 10 is turned on, is turned off. The burden on switch 10 due to sudden flow out is reduced.

Next, the result of numerical analysis of the antenna device according to the second embodiment will be described. Figure 4 shows the calculated reflection characteristics of the antenna device according to Example 2. In Fig. 4, the solid line In the case of the structure shown in FIG. 3, a dashed-dotted line b is a stub in the noisy line 6 when analyzed with only the first conductor 3, the second conductor 4, and the switch 10 without the bias line 6. This is the calculation result when 7 is not added. By attaching stub 7 in this way, you can raise it if you do not! It can be seen that the reflection characteristics can be improved to the same level as in the case where the noise line 6 is not present.

FIG. 5 shows the calculated radiation characteristics of the antenna device according to the second embodiment. In Fig. 5, d, e, f, and g are the polarization components of the radiation pattern. The coordinate system is as shown in Fig. 3, assuming that switch 10b is ON and switch 10c is OFF. Figure 5 (a) shows the cut surface at φ = 90 °, and (b) shows the cut surface at φ = 0 °. The thin lines e and g are φ components, and the thick lines d and f are Θ components. When switch 10b is set to ON, the main polarization direction is the vertical direction of the page. Therefore, when φ = 90 °, the zero component becomes the main polarization component, and when φ = 0 °, the φ component becomes the main polarization component. The result in Fig. 5 shows this, and also shows that the cross-polarized component is suppressed. On the other hand, when switch 10c is set to ΟΝ and switch 10b is set to OFF, the polarization direction is the horizontal direction on the paper, with 0 component at = 0 ° and φ = 90. Then, the φ component becomes the main polarization component. In this way, it is possible to switch the polarization direction.

Example 3

[0029] An antenna device according to Embodiment 3 of the present invention will be described with reference to Figs. FIG. 6 is a perspective view showing the configuration of the antenna apparatus according to Embodiment 3 of the present invention. FIG. 7 is a diagram showing another configuration of the antenna apparatus according to Embodiment 3 of the present invention.

FIG. 6 (a) is a front perspective view of a planar antenna (antenna device), and FIG. 6 (b) is a rear perspective view of the planar antenna (antenna device). In FIG. 6, the same symbols as those in FIG. 1 are omitted. A slot 12 is opened in the ground conductor 2 under the bias line 6.

[0031] Switching the polarization direction by ONZOFF of the switch 10 is the same as in the first embodiment. A slot 12 having a length of about λ Ζ2 is opened from the edge of the first conductor 3 at a position that is an integral multiple of λ Ζ2. In this way, by the same action as the tip open stub 7 described above, the bias line 6 at the edge of the first conductor 3 can be regarded as the force applied to the RF signal as if it were an open end, and propagation of the RF signal is prevented. Can be reduced. Here, the length and position of the slot 12 are optimized at the time of design, which is not strictly λ 2 or an integer multiple of λ 2. [0032] In each of the planar antennas (antenna devices) described above, the switch 10 may be a MEMS (Micro Electro Mechanical System) switch using a micromachining technology. In this case, the planar antenna patterns 3 and 4, the switch 10, and the bias line 6 can be integrally formed, so that the processing accuracy is improved. Micromachining technology is very effective in the high-frequency band where the physical size of the antenna is small, because it allows processing in units of microns.

[0033] Further, in each of the above-described planar antennas (antenna devices), by using a material having a high resistivity for the bias line 6, the RF signal is further attenuated and the influence on the antenna characteristics is reduced. can do.

[0034] As a means for reducing the propagation of the RF signal, in addition to the above-described open-ended stub 7 and the slot 12 provided in the ground conductor 2, as shown in FIG. A conductor pattern 13 that forms a capacitor may be formed.

The wiring location of the bias line 6 of the planar antenna (antenna device) described above does not necessarily have to be as shown in FIGS. 1 to 7, and the bias line is wired in a cross shape around the planar antenna. Is also possible. In this case, even if the polarization is switched, the relative position of the bias line does not change, so that it is possible to suppress changes in characteristics during operation when the polarization is changed.

[0036] In the above-described planar antenna device (antenna device), the shape need not necessarily be a rectangle, and may be a polygon. Also, when it is necessary to load the switch for a purpose other than to provide the polarization switching function, it is effective to provide a stub by passing it over the antenna pattern as in the present invention. .

Claims

The scope of the claims

[1] A planar rectangular patch antenna,

A dielectric substrate;

A ground conductor formed on the back surface of the dielectric substrate;

A rectangular annular first conductor formed on the surface of the dielectric substrate;

A rectangular second conductor formed inside the first conductor to form a surface of the dielectric substrate and a closed annular first slot;

Switches disposed on diagonal lines of the rectangular first and second conductors so as to couple the first conductor and the second conductor;

A bias line wired on the same plane as the first and second conductors to control the switch;

An open-ended stub connected to the bias line and having a length of 1Z4 of wavelength, and near the corner of the first conductor of the rectangle is wider than the width of the bias line below the bias line. A second slot is formed,

The bias line is wired so as to bridge the first conductor at a portion where the first conductor and the second slot intersect,

The feeding point is located at the center of the second conductor

An antenna device characterized by that.

[2] The switches are four pieces arranged on two diagonal lines of the rectangular first and second conductors,

The bias lines are four for controlling four switches,

The tip open stubs are four respectively connected to four bias lines; and

The second slot is 4 corresponding to 4 switches.

The antenna device according to claim 1, wherein:

[3] The switch is two pieces arranged on the first diagonal of the rectangular first and second conductors,

The bias line is two for controlling ^two switches, The tip open stubs are two respectively connected to two bias lines; and

The second slot is two corresponding to two switches,

The annular first slot is straddled so as to connect the first and second conductors on a second diagonal different from the first diagonal of the rectangular first and second conductors. The conductor pattern further formed

The antenna device according to claim 1, wherein:

[4] Planar rectangular patch antenna,

A dielectric substrate;

A ground conductor formed on the back surface of the dielectric substrate;

A bias line that is wired on the same plane as the first and second conductors and controls the switch;

Near the corner of the rectangular first conductor, a second slot wider than the width of the bias line is formed under the bias line,

A third slot having a wavelength of 1Z2 is formed in the ground conductor so as to be orthogonal to the bias line,

The feeding point is located at the center of the second conductor

An antenna device characterized by that.

[5] The switches are four pieces arranged on two diagonal lines of the rectangular first and second conductors,

The bias lines are four for controlling four switches, The second slot is four corresponding to the four switches,

And

The third slot is four corresponding to four bias lines.

The antenna device according to claim 4, wherein:

The switch is a MEMS switch

The antenna device according to any one of claims 1 to 5, wherein the antenna device is provided.