JPS63219204A - Antenna for portable radio equipment - Google Patents

Abstract

PURPOSE:To obtain a small sized low posture antenna capable of diversity communication by incorporating an inverse-F shaped antenna and a meandering antenna or the like, feeding power individually to transmission and reception parts, using one as a transmission/reception common antenna and using the other as a reception exclusive antenna while replacing antenna with a filter of branching filter structure. CONSTITUTION:A reception section (not shown in figure) is connected to a feeding coaxial line 6 and a transmission section is connected to balanced feeders 7, 8 via a balancer 9, then the sneak of a transmission wave radiated from a transmission section via an antenna to a reception section is reduced remarkably. Then the transmission wave is replaced by a simple filter of branching filter constitution and the inverse- F shaped antenna covers only a reception frequency band, then the broadwise direction perpendicular to the symmetrical axis is reduced to attain the small sized antenna. Then the transmission/reception section including a branching filter is connected to the feeding coaxial line 6 and another reception section is connected to balanced feeders 7, 8 via a balancer 9, then the directivity diversity reception is attained by the difference in the directivity between the inverse-F shaped antenna 3 and the zigzag strip line antenna 4 and the diversity communication is realized by a small sized antenna system.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an antenna for a portable radio device, and more specifically, to a portable radio device used when transmitting and receiving simultaneous calls by allocating frequency bands to each transmitter and receiver. This relates to the structure of small antennas used in aircraft.

[Conventional technology]

2. Description of the Related Art In order to make portable radio terminal devices such as portable telephones more convenient to carry, a major challenge is to reduce the size of the main body of the radio device, lower the profile of the antenna, and incorporate the antenna into a housing, that is, to make it more compact.

Conventionally, in order to deal with such problems, two narrowband inverted F antennas 3-1 and 3 were installed on the ground 1, focusing on the fact that the frequency bands of the transmitted wave and the received wave are different, as shown in Fig. 2. It is known that the antenna is made smaller by arranging two antennas in parallel and branching a single feeder line 6 near the antenna to feed the antenna.
I Nissneepy”Proceeding of
I S A P ”'85.

pp. 429-432). As shown in FIG. 3, as an antenna for a radio device that uses diversity reception, an inverted F-shaped antenna 18 for both transmission and reception and an inverted F-shaped antenna 19 for reception only are arranged side by side in the radio device housing 20 to enable diversity reception. (Page 271, Volume 3 of the Proceedings of the 1986 Institute of Electronics and Communication Engineers National Conference).

[Problem that the invention seeks to solve]

As portable mobile terminals become smaller and smaller to the point where pocketable phones can be realized, the burden on the splitter system has been reduced to reduce the size of the splitter that separates the transmitted and received waves within the terminal. This is a big problem, but the above-mentioned conventional technology does not take this point into consideration, and the transmission wave wraps around the receiving section, which becomes a big problem. Furthermore, in the structure shown in Fig. 2 above, in which the receiving frequency band and the transmitting frequency band are coupled to two narrow-band antennas, the two inverted F-shaped antennas are electromagnetically coupled. It was impossible to get them extremely close to each other, and there was a problem in that it was not possible to increase the volume reduction effect of the antenna system as a whole. Furthermore, in a diversity communication system using two inverted F-shaped antennas, for the same reason, there is a limit to how close they can be to each other, resulting in an increase in the volume of the entire antenna system.

An object of the present invention is to further reduce the volume of the antenna system and to realize a small antenna that can reduce the burden on the duplexer system.

[Means for solving problems]

In order to achieve the above object, the antenna according to the present invention is provided by installing a single inverted F antenna with a longitudinal symmetry axis on a grounded ground such as a radio casing, and attaching an appropriate value to the top surface of the inverted F antenna. A retaining layer having a dielectric constant is provided, a stripline antenna is placed on the retaining layer symmetrically with respect to the axis of symmetry, and power is supplied to the inverted F-shaped antenna at one point on the axis of symmetry, and the stripline antenna is By separately feeding the inverted F antenna in the vicinity of the symmetry axis and using the two strip antennas individually for transmission and reception,
Alternatively, this can be achieved by using the above two strip antennas, one for both transmission and reception and the other for reception only.

[Effect]

The inverted F-shaped antenna has an electric field concentrated at its edge, forming a magnetic current wave source, and its top surface acts as a finite ground for the stripline antenna. Since the stripline antenna is symmetrically and balancedly excited with respect to the symmetry axis of the inverted-F antenna, it does not affect the feeding section of the inverted-F antenna located on the symmetry axis. Therefore, when the strip line antenna is completely balancedly fed, the inverted F-shaped antenna and the strip antenna operate independently. Therefore, if one antenna is used as a receiving antenna and the other is used as a transmitting antenna, the amount of transmitted waves going around to the receiving section is extremely small. In this case, since the inverted F-shaped antenna only needs to cover either the transmitting or receiving frequency band, the width can be reduced. The increase in volume caused by the overlapping of two inverted F-shaped antennas and strip antennas is not a problem because the thickness of the strip line and the thickness of the dielectric can be made extremely thin. Therefore, it is possible to realize a small, low-profile antenna with good transmission/reception isolation, in which the duplexer can be replaced with a QL filter.

In addition, in an inverted F-type antenna, two co-directional magnetic current sources that are generated in the axial direction symmetrically about the axis of symmetry mainly contribute to the operation, whereas in a stripline antenna, two co-directional magnetic current sources that are generated symmetrically in the axial direction and symmetrical to the axis of symmetry contribute to the operation. Since the two current sources facing each other mainly contribute to the operation, the directivity characteristics of the two are significantly different. For example, in a plane that includes the axis of symmetry and is perpendicular to the top surface of the inverted F-shaped antenna, the electromagnetic fields caused by the magnetic current sources strengthen each other, and the electromagnetic fields caused by the current sources cancel each other out. Therefore, if one antenna is used for both transmitting and receiving purposes and the other is used as a receiving antenna, directional diversity reception becomes possible, and a small, low-profile antenna capable of receiving diversity can be realized without using two inverted F-shaped antennas.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a perspective view showing an embodiment of an antenna according to the present invention. 1 is a grounding ground formed by a part of the housing, 2 is a support layer with an appropriate dielectric constant, 3 is an inverted F-shaped antenna, 4 is a zigzag strip line antenna, 5 is a feeding point of the inverted F-shaped antenna, 6 is a feed coaxial for an inverted F-type antenna, 7 and 8 are balanced feed lines for a zigzag strip line antenna, 9
is a balancer, and 10.11 is a feeding point of a zigzag stripline antenna.

This embodiment has a symmetrical structure with a line passing through the feeding point 5 and parallel to the longitudinal direction of the inverted F-shaped antenna 3 as an axis of symmetry, and with respect to a half plane passing through this axis of symmetry and perpendicular to the ground.

For this reason, by connecting a receiving section (not shown) to the feed coaxial IX6 and connecting the transmitting section to the balanced feed lines 7 and 8 via the balancer 9, both of the transmitted waves from the transmitting section are sent to the receiving section. The wraparound through the antenna is significantly reduced, the duplexer can be replaced with a filter with a simple configuration, and the inverted F-shaped antenna only needs to cover the receiving frequency band, so the width direction perpendicular to the axis of symmetry is shortened. This makes it possible to reduce the size of the antenna.

Next, by connecting a transmitting/receiving section including a duplexer to the feed coaxial 6 and connecting a separate receiving section to the balanced feed lines 7 and 8 via the balancer 9, the inverted F-shaped antenna 3 and the zigzag By utilizing the difference in directivity of the stripline antenna 4, directional diversity reception becomes possible, and diversity communication can be realized with a small antenna system.

Although one embodiment of the antenna according to the present invention has been described above, the present invention is not limited to the above embodiment.

The stripline shape of a stripline antenna provides high gain when the total length is close to the resonance length, but the inverse F
The antenna is designed in a zigzag pattern to utilize the small space on the top surface of the antenna, and it is obvious that it can be modified in various ways depending on the application.

〔Effect of the invention〕

According to the present invention, it is possible to integrate an inverted F-shaped antenna and a meandering folded strip line antenna, which have different directivity characteristics that are not electrically coupled to each other, so that by feeding power to each transmitter and receiver separately, a one-wavelength splitter can be created. By using one of the antennas as a transmitting/receiving antenna and the other as a reception-only antenna, a small low-profile antenna capable of diversity communication can be realized. I can do it.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of an antenna according to the present invention;
Perspective views of small antennas for portable mobile terminals, Figures 2 and 3
Each figure is a perspective view of a small antenna system for a portable mobile terminal using two conventionally known inverted F-shaped antennas arranged side by side. 1... Grounding ground, 2... Support layer, 3... Inverted F-shaped antenna, 4... Zigzag strip line antenna,
5... Inverted F antenna feeding point, 6... Inverted F type antenna feeding coaxial, 7.8... Balanced feed line, 9... Balancer,
10.11... Zigzag strip line antenna feeding point, 18... Inverted F-shaped antenna for transmitting and receiving, 19...
Reception-only inverted F-shaped antenna, 20... housing.

Claims (1)

[Claims] 1. An inverted F-shaped antenna installed on a grounded ground and having a symmetry axis in the longitudinal direction; and a dielectric holding layer provided on the surface of a metal plate forming the inverted F-shaped antenna. , first and second strip line antennas arranged symmetrically with respect to the symmetry axis on the holding layer, and the first and second inverted F-shaped antennas arranged near the symmetry axis. An antenna for a portable radio device configured to include a power feeding section. 2. In the antenna described in item 1, the first and second
A stripline antenna for portable radios in which the stripline has a zigzag shape.