JPH1051220A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device which can be easily produced and needs no matching device by adding a conductor element to an antenna element in parallel to a grounding electrode plate and adjusting the space between the conductor element and the grounding electrode plate and also the length of the conductor element to secure matching with a feeding part at the desired frequency. SOLUTION: An antenna element 1 is set vertical to a grounding electrode plate 3, and an input impedance includes the resistance and inductance components. When a conductor element 4 is connected to the element 1 so as to be in parallel to the plate 3 a new capacitor is formed consisting of the element 4 and the plate 3. The matching is secured with a feeding part 2, when the capacity of the capacitor is properly decided based on the space H between the element 4 and the plate 3 and the area S of the plate 3. If the relevant resonance frequency is higher and lower than the desired frequency, the length W of the element 4 is increased and reduced respectively. Thus, the desired resonance frequency is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device used for a portable radio used for mobile communication.

[0002]

2. Description of the Related Art Conventionally, whip antennas, helical antennas and inverted F antennas have been used as antenna devices for portable radios. As a conventional example of the whip antenna, one described in Japanese Patent Application Laid-Open No. 6-152221 is known. FIG. 4 shows a configuration of a conventional whip antenna.
The whip antenna 101 is matched with the wireless circuit unit 108 by the matching unit 112 and emits an electromagnetic wave. Matching device 11
2 is a transmission line 105 connected to a coaxial line 109 at a connection point 107;
0, the transmission line length, the capacitance value of the capacitor 111, the connection point 107 of the coaxial line 109, and the capacitor 1
Matching is obtained by optimizing the positions of the eleven connection points 110.

[0003]

However, in the above-mentioned conventional whip antenna, a matching device is required between the whip antenna and the radio circuit unit, and the matching device occupies a certain space. There has been a problem that as the size of the radio becomes larger, the structure becomes more complicated and the production becomes more difficult. Further, there is a problem that a transmission loss occurs in the matching device, and the radiation power from the antenna decreases.

An object of the present invention is to solve such a conventional problem and to provide an antenna device which can be easily manufactured and does not require a matching device.

[0005]

According to the present invention, in order to achieve the above object, the antenna element is provided with a conductor element parallel to the ground electrode plate, and the distance between the conductor element and the ground electrode plate and the conductor element are provided. By adjusting the length, matching with the feeder at a desired frequency can be obtained, whereby an antenna device which is easy to manufacture and does not require a matching device can be obtained.

[0006]

According to the first aspect of the present invention, the antenna element is provided with a conductor element parallel to the ground plate, and the distance from the conductor element to the ground plate and the length of the conductor element are provided. Is adjusted to obtain a matching with the feeder at a desired frequency, and has an effect that an antenna device having a simple structure and requiring no matching device can be realized.

According to a second aspect of the present invention, the earth pole plate of the antenna according to the first aspect is formed in an L shape, and the radiation of the vertically polarized component is increased. Has the effect of improving the gain of the antenna.

FIG. 1 shows the configuration of a first embodiment of the present invention. In FIG. 1, the antenna element 1 is connected to the anode side of the power supply unit 2 and has a function of radiating power from the power supply unit 2 to the air. Ground plate 3
Are connected to the cathode side of the power supply unit 2 and are arranged in parallel with the conductor element 4. The conductor element 4 crosses the antenna element 1 and is electrically connected.

The operation of the antenna device configured as described above will be described with reference to FIG. The antenna element 1 is perpendicular to the ground electrode 3, and the input impedance has a resistance component and an inductance component. When the conductor element 4 is connected to the antenna element 1 so as to be parallel to the ground plate 3, a new capacitor is formed by the conductor element 4 and the ground plate 3. FIG. 2 shows an equivalent circuit at this time.
Since FIG. 2 shows an LRC series resonance circuit, matching can be obtained by appropriately selecting the capacitance C of the capacitor, and the radiation power is maximized. Therefore, when the capacitance C of the capacitor is determined to be an appropriate value based on the distance H from the conductor element 4 to the ground electrode 3 and the area S of the ground electrode 3, matching with the power supply unit 2 can be obtained. If the resonance frequency at this time is higher than the desired frequency, the length W of the conductor element 4 is increased, and if the resonance frequency is lower, the length W of the conductor element 4 is shortened to obtain a desired resonance frequency. Can be.

As described above, according to the first embodiment of the present invention, the antenna element 1 and the ground electrode 3 are connected to the anode and the cathode of the feeder 2 respectively, and the antenna element 1 is connected to the conductor element 4.
Is connected in parallel with the ground electrode plate 3, matching with the power supply unit 2 can be obtained at a desired frequency without using a matching unit. The antenna element 1 and the conductor element 4
Is linear in FIG. 1, but may be plate-shaped.

(Embodiment 2) FIG. 3 shows a configuration of a second embodiment of the present invention. In FIG. 3, the antenna element 1 is connected to the anode side of the power supply unit 2 and has a function of radiating power from the power supply unit 2 to the air. Ground plate 3
Are connected to the cathode side of the power supply unit 2 and are arranged in parallel with the conductor element 4. The conductor element 4 crosses the antenna element 1 and is electrically connected. The ground electrode 5 vertically intersects with the ground electrode 3 so as to form an L-shape, and is electrically connected to the ground electrode 3. actually,
The ground plate 3 and the ground plate 5 are manufactured by bending a single metal plate.

In this embodiment, in addition to the operation of the first embodiment, the ground electrode 5 is provided vertically at the end of the ground plate 3 so that the earth current flowing through the ground plate 3 can be reduced. Flows vertically along the ground electrode 5. Since this ground current radiates vertically polarized waves, the ground plate 5 operates as an antenna, and the gain is improved.

As described above, according to the second embodiment of the present invention, the gain can be improved by providing the ground electrode 5 vertically to the end of the ground electrode 3.

In the present embodiment, the angle θ at which the ground plate 3 and the ground plate 5 intersect is not limited to 90 °, but may be any L-shape. Further, the earth electrode 5 may be changed from a plate shape to a linear shape.

[0015]

As described above, according to the present invention, a conductor element parallel to a ground plate is disposed on an antenna element, and the distance between the conductor element and the ground plate and the length of the conductor element are two.
By adjusting the two parameters, an advantageous effect of realizing an antenna that does not require a matching device can be obtained. In addition, by bending the ground plate in an L shape, the ground plate can function as an antenna, and the effect of improving gain can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a configuration of an antenna device according to a first embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram according to the first embodiment of the present invention.

FIG. 3 is a schematic perspective view showing a configuration of an antenna device according to a second embodiment of the present invention.

FIG. 4 is a schematic block diagram showing a configuration of a conventional antenna device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna element 2 Feeding part 3, 5 Ground plate 4 Conductor element

Claims (2)

[Claims] An antenna element is provided with a conductor element parallel to a ground electrode plate, and a distance between the conductor element and the ground electrode plate and a length of the conductor element are adjusted so that the antenna element can be connected to a feeder at a desired frequency. An antenna device for obtaining matching. 2. The antenna device according to claim 1, wherein the ground electrode is formed in an L shape.