JP2743733B2 - Microstrip antenna device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio antenna, and more particularly to a multi-resonant microstrip antenna device for transmitting or receiving signals at a plurality of different frequencies.

[0002]

2. Description of the Related Art An open-type planar circuit resonator formed on a dielectric substrate is called a microstrip antenna. The resonance frequency of the microstrip antenna changes depending on the perimeter of the planar circuit and the dielectric constant of the dielectric. FIG. 5 shows an example of a conventional microstrip antenna, and FIG.
(2) shows the characteristics. In FIG. 5, 51 is a copper foil,
52 is a power supply line, and 53 is a ground line. FIG. 6 (1),
As shown in (2), the microstrip antenna is an antenna that resonates at a single frequency, and the band at that frequency is narrow, and it is difficult to transmit and receive at multiple frequencies.

[0003]

As described above, the resonance frequency of a microstrip antenna can be adjusted by changing its circumference or dielectric constant.
However, the microstrip antenna is an antenna that resonates at a single frequency and has a feature that the band at that frequency is narrow, so that it has a drawback that it is difficult to use it at a plurality of frequencies.

An object of the present invention is to provide a multi-resonant microstrip antenna device that can be used at a plurality of frequencies in view of the above-mentioned conventional problems.

[0005]

In order to achieve the above-mentioned object, the present invention provides a notch provided in an open planar circuit formed on a dielectric substrate, wherein a notch provided at a specific frequency such as an LC series resonance circuit is provided. Were combined with a resonance circuit having a low impedance.

[0006]

[Function] By attaching a resonance circuit having a low impedance at a specific frequency to the notch provided on the microstrip antenna, an effect similar to that in which the peripheral length of the microstrip antenna is reduced at the resonance frequency of the resonance circuit is obtained. can get. By adjusting the resonance frequency of the resonance circuit, the mounting position, and the length of the cut, a multi-resonance microstrip antenna common to a plurality of target frequencies can be realized.

[0007]

Embodiments of the present invention will be described below. FIG. 1 is a structural explanatory view showing an embodiment of the present invention, and FIGS.
FIG. 4 is a characteristic diagram of the microstrip antenna device of the present invention.

In FIG. 1, reference numeral 10 denotes a microstrip antenna, 11 denotes a copper foil, 12 denotes a feed line, and 14 denotes a ground line. Then, the microstrip antenna 10 tuned so as to resonate at the frequency f1 by providing the cut 15 is
A resonance circuit 13 at a frequency f2 is provided at a position where resonance occurs at a frequency f2 if a short circuit occurs. Since the impedance of the resonance circuit 13 is high at the frequency f1, the microstrip antenna 10 operates as an antenna adjusted to resonate at the frequency f1.

At the frequency f2, the impedance of the resonance circuit 13 becomes low, so that the resonance circuit 13 resonates at the frequency f2. FIG.
4 to 4 show resonance frequency characteristics and horizontal and vertical directional characteristics of the microstrip antenna device of the present invention. In these figures, f1 = 820 MHz and f2 = 950 M
Hz. It can be seen that the antenna is matched at both frequencies f1 and f2, and that the gain is obtained.

[0010]

As described above, by attaching the resonance circuit to the notch provided on the microstrip antenna, the microstrip antenna can resonate at a plurality of frequencies. Therefore, according to the present invention, it is possible to realize a multi-resonant microstrip antenna that performs transmission or reception at a plurality of different frequencies.

When the antenna of the present invention is used in a portable telephone, it operates as a housed transmission / reception antenna, so that there is an advantage that the antenna can be reduced in size and built in.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing one embodiment of the present invention.

FIG. 2 is a characteristic diagram showing characteristics of the microstrip antenna device of the present invention.

FIG. 3 is a characteristic diagram showing characteristics of the microstrip antenna device of the present invention.

FIG. 4 is a characteristic diagram showing characteristics of the microstrip antenna device of the present invention.

FIG. 5 is a configuration explanatory view showing an example of a conventional microstrip antenna device.

FIG. 6 is a characteristic diagram showing characteristics of a conventional microstrip antenna device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Microstrip antenna 11 Copper foil 12 Feeding line 13 Resonant circuit 14 Grounding line 15 Notch

Claims (1)

(57) [Claims] 1. An open planar circuit formed on a dielectric substrate.
Notches are provided where no feeder line is located.
A microstrip antenna device in which a resonance circuit having a low impedance at a specific frequency is formed in a recess.