JPS6234407A - Antenna for radio equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] In an inverted F-type antenna in which a plate-shaped radiating element is arranged parallel to the surface of a metal radio casing, there is a gap between the radio casing and the plate-shaped radiating element. A monopole element with a resonant length is provided on the open end side of the antenna, and each resonates at a different frequency, thereby realizing a compact antenna with wideband characteristics.

[Industrial application field]

TECHNICAL FIELD The present invention relates to a miniaturized antenna for a radio device such as a portable radio telephone.

[Conventional technology]

The radio device has, for example, the configuration shown in FIG. 4, and the audio signal from the transmitter 16 is amplified by the low frequency processing section, and the transmitting section 18 has a transmission frequency of, for example, 800 MHz.
z modulated and applied to the power amplifier 19. The signal amplified by the power amplifier 19 is applied to the antenna 11 via the duplexer 12 and transmitted. Further, the signal received by the antenna 11 is applied to the receiving section 13 via the duplexer 12. This receiving section 13 demodulates the signal into a low frequency signal, which is added to the low frequency processing section 14 and amplified to the receiver 15.
added to.

When such a radio device is configured to be portable, a 1/4 wavelength monopole antenna is often used as the antenna 11. However, this monopole antenna has the disadvantage that it protrudes from the radio housing for a long time, which obstructs operation.

Therefore, recently, an inverted F antenna using a plate-shaped radiating element has been adopted. This inverted F antenna uses a metal radio casing as a grounding plate, arranges a plate-shaped radiating element parallel to the radio casing, and connects and fixes one end of the plate-shaped radiating element to the radio casing. A power feeding point is provided at a predetermined position between the tip and the grounding part.

Since this inverted F antenna can receive horizontal and vertical polarization components, it is suitable as an antenna for wireless communication in urban areas where the plane of polarization rotates.

[Problem that the invention seeks to solve]

Portable radio telephones use two frequencies in order to transmit and receive at the same time, similar to ordinary telephones. Therefore,
An antenna for a portable radio telephone is required to have wideband characteristics.

However, the aforementioned inverted F antenna has a single resonant frequency and a relatively narrow band. In this inverted F antenna, it is known that the band is wider when the corner of the plate-shaped radiating element is grounded than when the center of one side of the plate-shaped radiating element is grounded. However, even if such means are adopted, the band will only become slightly wider.

Broadband characteristics can be obtained by increasing the distance between the casing, which serves as a grounding plate, and the plate-shaped radiating element, but in order to achieve a practically sufficient broadband characteristic, the distance must be made very large. Therefore, the advantage of the inverted F antenna, which can be made smaller, is lost.

The present invention improves the above-mentioned conventional drawbacks, and aims to provide broadband characteristics with a simple configuration.

[Means for solving problems]

The radio antenna of the present invention will be described with reference to FIG. 1. A plate-shaped radiating element 2 is arranged parallel to the surface of a metal radio casing 1, and one end of the plate-shaped radiating element 2 is connected to the radio casing 1. , a monopole element 3 with a resonant length is provided at the upper part of the open end between the radio housing 1 and the plate-shaped radiating element 2, and power is supplied by a coaxial cable 4 etc. consisting of an inner conductor 4a and an outer conductor 4b. It is.

It is to be noted that the monopole element 3 is loaded with an inductance to shorten its length, and the radio device housing 1 is provided with a receiver 5 and a transmitter 6.

[Effect]

An antenna is constructed in which the plate-shaped radiating element 2 and the monopole element 3 resonate at different resonance frequencies, respectively, and can have broadband characteristics. Also, the length of the monopole element is l/1
Since the wavelength can be reduced to about 0, it can be made smaller.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a partially cutaway side view of an embodiment of the present invention, in which a radio device housing 1 is made of metal and has the structure shown in FIG. 4 built therein. A plate-shaped radiating element 2 is placed parallel to the top surface of this radio device housing 1.
The coaxial cable 4 The inner conductor 4a of is connected to the plate-shaped radiating element 2, and the outer conductor 4b
is connected to the radio device housing 1 to supply power.

In this way, when one end of the plate-shaped radiating element 2 is set as the ground end, the length to the open end is selected to be approximately 1/4 wavelength. Also, the receiver 5. Transmitter 6. Other switches (not shown) for operating the wireless device are also provided.

FIG. 2 is a VSWR characteristic curve diagram, for example, the frequency f
, is the resonant frequency of the inverted F antenna by the plate-shaped radiating element 2,
By setting the frequency f2 to the resonance frequency of the monopole element 3, broadband characteristics can be obtained.

Also, if a 1/4 wavelength monopole element 3 is used, a very wide band antenna can be constructed, but if it is sufficient to cover the desired band, the length of the monopole element 3 can be significantly shortened. For example, as an antenna for the 800 to 900 MHz band in a wireless telephone system, the length of the monopole element 3 is 1/1
The height of the inverted F antenna consisting of the wavelength plate-shaped radiating element 2 can be reduced to approximately 1/100 wavelength. Therefore, compared to conventional radio antennas, the antenna can be made smaller and have wider band characteristics.

FIG. 3 is a partially cutaway side view of another embodiment of the present invention;
The same reference numerals as in FIG. 1 indicate the same parts, and this shows a case where a thin film conductor 2a on a dielectric substrate 2b is used as a plate-shaped radiating element. This thin film conductor 2a and no '! JA machine housing 1
Since the opposite side becomes the open end, the monopole element 3 is provided on the upper part.

The antenna of this embodiment consists of a thin film conductor 2a and a radio device housing 1.
Since the structure is such that a dielectric material is filled between the antenna and the antenna, the antenna is mechanically strong, small in size, and stable. Moreover, its production becomes easy.

〔Effect of the invention〕

As explained above, the present invention provides an inverted F antenna in which the plate-shaped radiating element 2 is arranged parallel to the surface of the radio device housing 1.
A monopole element 3 with a resonant length is provided on the top of the plate-shaped radiating element on the open end side, and by selecting each resonant frequency, a wideband An antenna can be realized. Furthermore, since the length of the monopole element 3 is only about 1/10 wavelength, there is an advantage that the portion protruding from the radio device housing 1 can be made small.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view of one embodiment of the present invention, FIG. 2 is a VSWR characteristic curve diagram, FIG. 3 is a partially cutaway side view of another embodiment of the present invention, and FIG. It is a block diagram of a radio device. 1 is a radio housing, 2 is a plate-shaped radiating element, 3 is a monopole element, 4 is a coaxial cable, 5 is a receiver, and 6 is a transmitter.

Claims (1)

[Claims] A plate-shaped radiating element (
2) to connect and fix one end of the plate-shaped radiating element (2) to the radio casing (1), and between the radio casing (1) and the plate-shaped radiating element (2). A radio antenna characterized in that a monopole element (3) having a resonance length is provided above the plate-shaped radiating element (2) on the open end side of the antenna.