JPS59172804A - Antenna for small-sized radio equipment - Google Patents

Abstract

PURPOSE:To obtain an antenna having a large antenna gain and a wide receiving frequency band width by providing a shape to an antenna element forming closed loops passing through each reactance circuit at plural end faces orthogonal to each other of the said element. CONSTITUTION:The antenna includes the antenna element 20 having the element for the 1st loop comprising A-B-C-D and the element for the 2nd loop comprising A-E-F-D connected in parallel with the element for the 1st loop, a variable capacitor 21 functioning as the reactance circuit for the tuning and for setting an output impedance connected in parallel with both the said elements, and a capacitor 22 connected to a connecting point A between both the said elements and the capacitor 21. The antenna element 20 has a shape where closed loops different from each other in side through each variable capacitor 21 is formed at the plural end faces orthogonal to each other. Thus, the antenna having a large antenna gain and a wide receiving frequency band width is obtained.

Description

[Detailed description of the invention] The present invention relates to an antenna for small radio equipment, and more particularly to an antenna for a small radio device.

The present invention relates to an antenna for a portable radio receiver.

Conventionally, portable radio receivers, particularly female individual selective calling receivers such as pagers, have been miniaturized so that users can carry them with them on a daily basis.

As the antenna used in the receiver, a loop antenna that can be built into the receiver is often used, and an air-core loop antenna without a magnetic core is also used to downsize the receiver.

Conventionally, this type of loop antenna, as shown in FIG.
It is connected to both ends of 1 and has a variable configuration. In this antenna, by selecting the values of the variable capacitor 11 and the capacitor 2, a desired output impedance can be obtained at a desired frequency. by the way.

When the frequency to be received becomes higher, the inductance value of the antenna element 10 or the capacitance values of the variable capacitor 11 and the capacitor 2 must be reduced. However, in this antenna, there is a limit to how much the capacitance value can be reduced, and in the end, the inductance value must be reduced. For this reason, in the antenna of FIG. 1, even though the receiver has a waveform capable of realizing a large loop antenna.

The drawback was that the maximum dimensions of the antenna were determined by the receiving frequency. Further, in this type of loop antenna, the antenna gain is about -16 dB of the dipole ratio in the 450 MHz band, for example, and in this region, the antenna gain increases as the aperture area of the antenna increases.

However, in the loop antenna shown in Fig. 1, the dimensions of the antenna are determined by the receiving frequency as described above, so the opening area of the antenna is 1/1/1 of the opening surface of the housing.
It is only used about 6 times.

The disadvantage was that the antenna gain was reduced.

Further, the loop antenna shown in FIG. 1 has a drawback that the Q value is large and the reception frequency bandwidth is narrow.

An object of the present invention is to provide a small radio antenna that can effectively utilize the space of a receiver that would otherwise be available in a loop antenna, increase the antenna gain, and widen the receiving frequency bandwidth. It is about providing.

According to the present invention, connected to both ends of the reactance circuit,
In a small radio antenna having a conductive element forming a closed loop with the reactance circuit, the conductive element has a shape in which a closed loop passing through the reactance circuit is formed on each of a plurality of mutually orthogonal end faces. A small radio antenna characterized by the following is obtained.

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 2, a first embodiment of the present invention is shown.

a first loop element consisting of A-B-C-D;
a conductive element (i.e., an antenna element) 20 having a second loop element consisting of A-E-F-D connected in parallel to the loop element; and the first loop element and the second loop element. A variable capacitor 21, which is a resistance circuit for tuning and setting output impedance, is connected in parallel to the first loop element, the second loop element, and the capacitor 21 at a connection point A.
and a capacitor 22 connected to the capacitor 22. antenna element 2
0 has a shape in which closed loops of different sizes passing through variable capacitors 21 are formed on a plurality of end faces that are orthogonal to each other.

The first loop element has a desired frequency (e.g. 4
The inductance L is large enough to easily satisfy the resonance condition when the capacitive circuit is loaded at 5'OMHz).
+ (e.g. 10 nH). The second loop element has an inductance L2 (for example, 50 nH) of such a magnitude that it is difficult to realize resonance conditions when the capacitive circuit is loaded at a desired frequency because the capacitance value is too small. .

The second loop element has a size that allows the use of two, for example, openings of the receiver housing at the same time. Said first
The inductance LO of the antenna element 20 in which the loop element and the second loop element are connected in parallel is determined by the equation, and when ILI<L2, LO is L1.In the antenna element 20, Although the aperture area of the antenna is the same as that of the second loop element and is larger, the inductance value is the same as that of the first loop element, so it is possible to realize an antenna that can easily obtain resonance conditions. In other words, in the second embodiment, it is possible to easily configure a tuning circuit at a desired frequency, and since the aperture area of the antenna is increased, an antenna with a large antenna gain and a wide reception frequency bandwidth is realized. You can.

When compared numerically, as shown in Figure 3, the frequency band when the voltage standing wave ratio VS■-2 (reflection coefficient -0.33) is as shown in Figure 3 for the conventional antenna configuration. 2.7 (MHz) as shown in FIG. 3(B), and 17.5 (MHz) as shown in FIG.
This means that it will expand approximately 6.5 times. In addition, the antenna gain is -16 dB for the antenna with the conventional configuration, and -12 dB for the antenna with the configuration of the present invention, which is 9.4 dB.
Gain is increased. In other words, the antenna gain is large.
An antenna with a wide receiving frequency bandwidth can be realized.

Referring to FIG. 4, a second embodiment of the present invention is shown.

An antenna element (i.e., a conductive element) 40, a variable capacitor 41 connected in parallel to the antenna element 40, and a connection point G between the antenna element 40 and the variable capacitor 41.
and a capacitor 42 connected to the capacitor 42 . The antenna element 40 includes an upper plate 40a, a side plate 40b, and a lower plate 40c.
It has a connecting plate 40d that connects the upper plate 40a and the lower plate 40c on the right side. The antenna element 40 is.

G-I (-I-J forms a first loop passing through the capacitor 41, and G- and -L-J form a second loop passing through the capacitor 41. Also in this embodiment, ' Similar to the embodiment shown in FIG. 2, the antenna element 40 has a shape in which a closed loop passing through a variable capacitor 41 is formed on each of two mutually orthogonal end surfaces (front and right side).

In this embodiment, as in the first embodiment, the tuning circuit can be easily configured, and the antenna gain is large.
An antenna with a large reception frequency bandwidth can be realized.

As described above, the present invention has the effect of making it possible to effectively utilize the space of the loop antenna receiver, realizing an antenna with a large antenna gain and a wide receiving frequency band.

In addition, conventional antennas only operate in the UHF band (406
~512 MHz), the capacitor 12 is 3
The value of the capacitor was changed for each divided frequency band, but according to the present invention, it is possible to realize a wide antenna with two frequencies, so the capacitors 22 and 42 can be of a common value, and are small enough to be easily mass-produced. It also has the effect of realizing an antenna for radio equipment.

Furthermore, since the present invention allows loop antennas to be configured in mutually orthogonal planes, it is possible to construct loop antennas in planes that are perpendicular to each other.
It also has the practical advantage of being able to improve the directivity characteristics by about dB and being able to receive changes in the magnetic field of radio waves no matter which direction it is facing.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional small radio antenna.
Fig. 2 is a perspective view showing a small radio antenna according to the first embodiment of the present invention, and Figs. 3 (4) and (B) show the wave number-reflection coefficient characteristics of the conventional antenna and the antenna of the present invention, respectively. The figure shown in FIG. 4 is a perspective view showing an antenna for a small radio device according to a second embodiment of the present invention. 10.20 and 40... antenna element (conductive element). 11.21 and 41...variable capacitor, 12°22
and 42... capacitor. I Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] 1. In an antenna for a small radio (having a conductive element connected to both ends of a reactance circuit and forming a closed loop together with the reactance circuit), the conductive elements each have a plurality of end faces perpendicular to each other. . An antenna for a small radio device, characterized in that the antenna has a shape in which a closed loop passing through the reactance circuit is formed.