JPH0495403A - Antenna system - Google Patents

Abstract

PURPOSE:To realize a small sized antenna whose length is reduced and which is tuned at plural frequencies by mounting plural inductance elements separately to the antenna. CONSTITUTION:Antenna elements 11-14 resulting from dividing a line antenna whose length is shorter than an operating wavelength into plural numbers and inductance elements 5-7 mounted to each antenna division as an inductive lumped constant element or distributed constant element are provided to the antenna system. Thus, in operating frequencies fT, fR, antenna elements 11, 12, 13, 14 and the mounted inductance elements 5, 6, 7 are resonated with respect to the frequency fT and the antenna elements 12, 13, 14 and the mounted inductance elements 6, 7 are resonated with respect to the frequency fR in this antenna and the built-in small sized antenna is resonated at two transmission and reception frequencies.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an antenna device used in a radio device.

BACKGROUND OF THE INVENTION Conventional antennas for portable radio devices include a whip antenna 1 with a length of about 7 wavelengths as shown in Fig. 4, and a helical antenna as shown in Fig. 5 when a shortened antenna is required. 1 has been commonly used. 2 is the power supply point,
3 is a wireless device housing.

Problems to be Solved by the Invention However, the above-mentioned conventional antenna is, in principle, a single tuning type antenna, and there is only one resonant frequency. Also, wavelength antennas are long and difficult to use depending on the frequency band used. Helical antennas, which were devised to eliminate the above drawbacks, can shorten the antenna length, but the band becomes narrower in proportion to the shorter antenna length.
It is difficult to cover the band of duplex radio equipment that uses different frequencies for reception. To improve this point, helical antennas that tune at two frequencies have been devised, but they are structurally complex and have low antenna gain.

The present invention aims to eliminate these drawbacks of conventional radio antennas and provide a radio antenna that is small, can be tuned at a plurality of frequencies, and has a high antenna gain.

Means for Solving the Problems In order to achieve the above object, the present invention divides the antenna element into a plurality of parts and loads a plurality of inductance elements in the divided parts, thereby reducing the capacitance component of the small whip antenna. cancellation, so that tuning can be achieved even if the antenna length is short.

Moreover, by loading a capacitance element in parallel with the loaded inductance element to form a resonant circuit, it has a characteristic that allows resonance at a plurality of frequencies.

Effect Therefore, according to the present invention, the antenna length can be shortened by distributingly loading a plurality of inductance elements to divided antenna locations, and the effect of a resonant circuit due to the capacitance element loaded in parallel with the loaded inductance element. This has the effect of realizing a compact antenna that can be tuned at multiple frequencies.

Example FIG. 1 shows the configuration of an embodiment of the present invention.

In FIG. 1, reference numerals 11 to 14 indicate antenna elements obtained by dividing a linear antenna shorter than the wavelength into a plurality of pieces. 5-7
is an inductance element as a lumped constant element or a distributed constant element having an inductive inductance loaded at the antenna dividing point.

8 is a key loaded in parallel with the inductance element 7.

It is a passitance element. , 9 is a matching circuit that matches the antenna impedance and the impedance of the radio device. 2 is a power feeding point, and 3 is a wireless device housing.

Now, the transmitting frequency of the duplex radio is fT, and the receiving frequency is fR.
Assume that fT<L. Loading inductance element 5
The element values of the resonant circuit consisting of the capacitance element 8 and the capacitance element 8 are selected so that it resonates at the higher frequency f of the two transmitting and receiving frequencies used. The impedance of this resonant circuit is high impedance when viewed at the receiving frequency f.

It has a characteristic that it becomes an inductance component when viewed at a lower transmission frequency fT.

Therefore, when looking at the frequency and fR at which this antenna is used, it can operate as the antenna shown in FIGS. 2(a) and 2(b) with equal savings.

That is, at fT, antenna elements 11, 12, 13, 14 and loading inductance elements 5. 6. It resonates at 7 and f.

In this case, it is possible to resonate with the antenna element 12, 13, 14 and the loading inductance 6.7, and it is possible to have the characteristic of resonating at two frequencies even though it is a small antenna that is shortened compared to the wavelength. .

FIG. 5 shows another embodiment of the invention. In this embodiment, an antenna capable of resonating at four frequencies can be realized by increasing the number of capacitance elements loaded in parallel to three as shown at 8° 22 and 23. In the above example, when four different transmission and reception frequencies are used within the radio housing 3, it is possible to use one antenna in common without using multiple antennas.

By increasing the number of antenna divisions, it is possible to resonate at even more frequencies.

Effects of the Invention As is clear from the above examples, the present invention has the following effects.

(1) A small antenna with low loss can be realized by distributing and loading a plurality of inductance elements.

(2) Conventional compact shortened antennas have narrow band and single tuning characteristics, but by using multiple resonant circuits, it is possible in principle to tune the antenna as many times as there are elements in the divided antenna. .

The characteristics (1) and (2) above eliminate the inevitable drawbacks that accompany miniaturization of antennas, and make it possible to provide antennas that are essential for realizing small portable radio devices. . AM, FM, TV with one antenna
It is possible to apply this method to automobile antennas that can receive multiple waves.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an embodiment of the antenna device according to the present invention, FIG. 2 (al, (bl) is a schematic perspective view for explaining the operation of the antenna device in FIG. A schematic perspective view showing another embodiment of the device, and FIGS. 4 and 5 are schematic perspective views showing the configuration of a conventional antenna device. 3. Wireless device housing, 5. 6. 7. ...Inductor element, 8.22.23...Capacitance element, gold circuit,
11.12.13.14...Antenna element. Drawer 9: Name of the agent, patent attorney Shige Takashi Awano, and one other person.

Claims (1)

[Claims] A linear antenna is divided into a plurality of parts, a lumped constant element or a distributed constant element having inductive inductance is loaded in the divided parts, and a capacitance element is loaded in parallel with at least one element of the loaded inductive inductance elements. An antenna device characterized in that the parallel inductance element and the capacitance element resonate in a frequency band used.