JPH1098331A - Planar antenna - Google Patents

Abstract

(57) Abstract: Two radiating conductor plates having different lengths are provided on one grounding conductor plate, and two plate-shaped inverted-F antennas having two self-resonant frequencies are fed to each other. Miniaturize and integrate. A radiating conductor plate (6) is provided in parallel to a ground conductor plate (2), and a short-circuited vertical flat plate (7) for short-circuiting the radiation conductor plate (6) is provided at a position deviated from the center of the radiating conductor plate (6). Distances L1 and L2 from the short-circuited vertical plate 7 to both ends of the radiation conductor plate 6 are set to be different from each other, and the portion of the radiation conductor plate 6 where the power supply cable 3 is provided has a first self-resonant frequency, Is inductively coupled to a portion having a second self-resonant frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna mounted on a portable telephone terminal, a small repeater amplifying device installed in an underground mall, a room in a building, and the like.
The present invention relates to improvement of an antenna.

[0002]

2. Description of the Related Art In recent years, portable telephones have been rapidly spread due to expansion of service areas such as cellular telephones, lower prices of apparatuses, and lowering of telephone call costs. In order to expand services in blind zones such as underground shopping malls, department stores and offices where radio waves from base stations do not reach, small indoor repeater amplifiers have been increasingly required.

[0003] For example, there are two types of antennas installed in a relay amplifying device for indoor installation, one using an external antenna such as a dipole antenna and the other using an internal antenna that does not impair the aesthetic appearance of a room. As the internal antenna, a planar antenna generally called a plate-shaped inverted-F antenna is used. This antenna is also called a microstrip inverted-F antenna.

FIG. 3 is a perspective view showing the structure of a conventional inverted-F planar antenna. The planar antenna is a ground conductor plate 2
Single-resonant or single-tuned plate-shaped inverted F, comprising a power supply cable 3 for supplying power to a power supply point at a predetermined distance from the position of the bent short stub of the radiation conductor plate 1 for matching. Antenna. FIG. 4 shows the reflection characteristics, and the usable comparison bandwidth having a reflection amount of -10 dB or less is 3.6%.

[0005] However, for example, the transmission and reception frequency difference of the 850 MHz band portable telephone system is about 45 MHz (about 5.3 MHz).
%), There is a problem in sharing the above antenna with one antenna.

FIG. 5 is a perspective view of a planar antenna actually used in a conventional relay amplifier for indoor installation.
The antenna shown in FIG. 3 is configured to resonate in both an uplink frequency band for receiving radio waves from the portable wireless terminal and a downlink frequency band for transmitting radio waves to the portable wireless terminal. Are arranged so as to face each other. That is, on one ground conductor plate 2,
Two radiation conductor plates 1 and 4 are provided, and power is supplied by power supply cables 3 and 5, respectively.

[0007]

However, the above-mentioned conventional antenna has the following problems. (1) In the antenna as shown in FIG. 5, the two radiating conductor plates 1 and 4 need to be arranged at a certain distance from each other due to the problem of mutual interference, so that miniaturization is difficult. (2) Basically, since the two radiation conductor plates 1 and 4 are arranged on one ground conductor plate 2, the number of components such as the power supply cables 3 and 5 and the cable fixing brackets is large, and the size and economy are reduced. I can not plan.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a planar antenna which can be reduced in size and cost, and which can cover both transmitting and receiving frequency bands.

[0009]

In order to achieve the above object, a planar antenna according to the present invention comprises a ground conductor plate, a radiating conductor plate disposed in parallel to the ground conductor plate, and a radiating conductor plate. A flat plate reverse plate comprising a short-circuited vertical flat plate which is connected at a right angle to one end of the conductive plate and is short-circuited and fixed to the ground conductive plate, and a feed cable which feeds a predetermined position of a side edge of the radiating conductive plate. In the F-shaped planar antenna, the radiating conductor plate is integrally formed to be shorter or longer than the length from the one end portion to which the short-circuited vertical flat plate is fixed to the opposite end portion, and The required bandwidth of the antenna is increased by increasing the interval between the first self-resonant frequency contributed by the radiation conductor portion on the feed side of the radiation conductor plate and the second self-resonance frequency contributed by the extended radiation conductor portion. That you set it broadly It is an butterfly.

[0010]

FIG. 1 is a perspective view showing an embodiment of the present invention, in which 6 is a radiation conductor plate, and 7 is a short-circuited vertical flat plate.
As shown in the figure, in the planar antenna of the present invention, a parallel radiating conductor plate 6 is disposed on a flat grounding conductor plate 2, and a short-circuited vertical flat plate is provided between the grounding conductor plate 2 and the radiating conductor plate 6. 7 is arranged at a position shifted from the center of the radiation conductor plate 6 by a predetermined distance,
The radiation conductor plate 6 and the ground conductor plate 2 are short-circuited and fixed. Power is supplied to the side end surface of the radiation conductor plate 6 from the short-circuited vertical plate 7 at any one of the arbitrary distances by the power supply cable 3.

Assuming that the length from the position of the short-circuited vertical plate 7 to one end of the radiation conductor plate 6 is L1 and the length from the other end to L2, the position of the short-circuited vertical plate 7 is L1 ≠ L2
It is decided to be. For example, in the embodiment of FIG.
It is configured to supply power to the longer one, that is, L1.

FIG. 2 is a diagram showing an example of the reflection characteristics of the planar antenna of the present invention shown in FIG. 1, where two self-resonant frequencies f1 and f2 are observed. The fractional bandwidth at the -10 dB point is 8.2.
%It has become. The longer-powered L1 side self-resonates at the frequency f1 while the other shorter L2 side is
Self-resonance occurs at the frequency f2 due to inductive coupling from the L1 side to which power is supplied. Therefore, a planar antenna having two self-resonant frequencies is realized by one feed point.
Seen from the side, it is a π-shaped antenna in which a short-circuited vertical plate 7 and a feeder line 3 are provided below a radiating conductor plate 6 which is long horizontally.

The difference or ratio between the lengths L1 and L2 from the position of the short-circuited vertical plate 7 to both ends of the radiation conductor plate 6 is determined in accordance with the difference or ratio between the two self-resonant frequencies f1 and f2. For example, the transmission frequency band and the reception frequency band of the actual mobile phone system are determined so as to have a bandwidth of the reflection amount of -10 dB.

In this embodiment, the short-circuited vertical flat plate 7 is used. However, the short-circuited vertical flat plate 7 does not need to be particularly flat, and a rectangular-shaped conductor block may be used in order to increase the mechanical strength.

[0015]

As described above, by implementing the present invention, a double-resonant or double-tuned planar antenna can be realized with a single radiation conductor plate, and the number of parts such as cables and metal fittings is reduced by half. It can be economical,
In addition, there is an extremely large effect for downsizing.

[Brief description of the drawings]

FIG. 1 is a perspective view of a double-tuned planar antenna according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of reflection characteristics of a double-tuned planar antenna according to the present invention.

FIG. 3 is a perspective view of a conventional single resonance plate-shaped inverted F antenna.

FIG. 4 is a diagram illustrating an example of reflection characteristics of a conventional single-resonance plate-shaped inverted F antenna.

FIG. 5 is a perspective view of a conventional double-tuned planar antenna.

[Explanation of symbols]

 1,4 radiation conductor plate 2 ground conductor plate 3,5 power supply cable 6 radiation conductor plate 7 short-circuited vertical plate

Claims (1)

[Claims] 1. A ground conductor plate, a radiating conductor plate disposed in parallel with and opposed to the ground conductor plate, and short-circuited to the ground conductor plate which is connected at a right angle to one end of the radiating conductor plate. A short-circuited vertical flat plate, and a feeding cable for feeding power to a predetermined position of a side edge of the radiation conductor plate. In the flat inverted F-shaped flat antenna, the radiation conductor plate has the short-circuited vertical flat plate fixed. The length of the radiating conductor plate on the feeding side of the radiating conductor plate is further extended from the one end side portion to be shorter or longer than the length to the opposite end side portion.
By widening the interval between the self-resonant frequency of the second and the second self-resonant frequency contributed by the radiation conductor portion of the extension portion,
A π-shaped planar antenna, wherein the required bandwidth of the antenna is set wide.