JPH10276024A - Antenna, and portable radio equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain sutisfactory characteristics in both states of being housed and being extended with simple constitution by operating only a helical coil in an element-housed state and operating a whip element capacitively coupled to the helical coil in an element-drawing-out state. SOLUTION: When housed, the element 22 is entirely housed inside a case 12 leaving a knob part 33 and the upper fitting part 35 of the element 22 is fitted and fixed to a main body 11. At this point, the helical coil 21 is operated as this antenna by a single body. Thus, when housed, it is turned to the 1/4 wavelength helical antenna of almost 50 Ω. On the other hand, when extended, since a metal pipe 25 is inserted in the helical coil 21, impedance itself is lowered and the helical coil 21 is operated as a simple power feeding element. Since the whip element 26 capacitively coupled to it pulls the impedance in a high direction again, the total antenna impedance becomes about 50 Ω.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna for a portable radio. In particular, the present invention relates to a portable wireless device that allows a user to select and use an extended state and a stored state of an antenna according to radio wave conditions.

[0002]

2. Description of the Related Art Conventionally, there is an antenna as described in Japanese Patent Publication No. Sho 62-28604 as a retractable antenna. This is shown in FIG. 3 as a conventional example.

As shown in FIG. 3, the portable wireless device comprises a transmitter / receiver main body 11 and a case 12 for protecting the same, and the case 12 is provided with a projection 14 on an upper surface 13. The power supply point 15 is provided on the transceiver body, and the protrusion 1 in the case is provided.
One end of the helical coil 21 arranged at 4 is fixed. On the other hand, the element 22 which can be extended and stored freely
Is a linear or helical whip element 26,
It is composed of a dielectric cover 32 that covers it.
When extended, the element 22 is fitted and fixed to the main body,
The helical coil 21 and the whip element 26 are capacitively coupled. At the time of storage, the entire element 22 is stored inside the case except for the knob 33, and is fitted and fixed to the main body. At that time, the whip element 26 and the helical coil 21
Are arranged at regular intervals, so that the capacitive coupling is disconnected.

[0004]

The conventional example shown in FIG.
At the time of storage, the helical coil 21 functions as an antenna as it is. Therefore, the impedance is determined by the ground of the transmitter / receiver main body, the arrangement of surrounding mechanical components, the state of the case 12, and the like. At this time, if the design is performed well, the impedance can be set to approximately 50Ω without using a matching circuit (for example, in an 800 MHz band and a 1.5 GHz band). Further, at the time of extension, the linear or helical whip element 26 is capacitively coupled to the helical coil 21 to function as an antenna. As the impedance characteristic, since two resonances are combined, a deviation occurs as compared with the case of storage. Therefore, there is a disadvantage that the impedance change during storage and extension cannot be completely eliminated, and perfect matching cannot be achieved in both states. FIG. 4 shows the frequency characteristic of the antenna impedance of the conventional example on a Smith chart. (A) is the storage characteristic,
(B) is the characteristic at the time of elongation.

[0005]

Means for Solving the Problems To solve the above problems,
The antenna of the present invention is composed of a helical coil connected to a transceiver, and an element that can be pulled out and stored in a case where a whip element is disposed above and a metal pipe or a metal block is disposed below via a dielectric. In the retracted state, only the helical coil operates, and in the retracted state, the metal pipe or metal block below the element is inserted inside the helical coil, and the helical coil itself becomes a low-impedance feed element, and is capacitively coupled to the helical coil. The whip element that operates is operated.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention. According to FIG. 1, the portable wireless device includes a transceiver main body 11 and a case 12 for protecting the same. A power supply point 15 is provided in the transceiver body, and is connected to the helical coil 21. On the other hand, the element 2 which can be extended and stored freely
2 is a linear or helical whip element 26
, A metal pipe (or metal block) 25 below the element 22, a dielectric rod 27 connecting the whip element 26 and the metal pipe 25, and a dielectric cover 3 covering these.
It is composed of two elements. Element 22 when extended
The lower fitting portion 34 is fitted and fixed to the main body, but the metal pipe (metal block) 25 is deformed to have a projection on the ring, and also serves as a stopper. In this state, although the helical coil 21 and the whip element 26 are capacitively coupled, a metal pipe (metal block) 25 is inserted inside the helical coil 21. At the time of storage, the element 22 is entirely stored inside the case 12 except for the knob 33, and the upper fitting portion 35 of the element 22 is fixed by being fitted with the main body. At this time, the helical coil 21 is operating alone as an antenna.

The antenna having such a configuration becomes a quarter-wave helical antenna of approximately 50Ω when housed. On the other hand, when the helical coil 21 is extended, a metal pipe (metal block) 25 is inserted into the helical coil 21.
Decreases the impedance itself (for example, about 30Ω),
The antenna functions simply as a feed element, and the whip element 26 capacitively coupled thereto pulls the impedance again in a higher direction, so that the total antenna impedance becomes about 50Ω. Adjustment of impedance can be performed by changing the strength of capacitive coupling. Specifically, the interval between the helical coil 21 and the whip element 26 is changed. FIG.
Next, the frequency characteristic of the antenna impedance of the present invention is shown on a Smith chart. (A) shows the characteristics at the time of storage, and (b) shows the characteristics at the time of extension.

[0008]

As described above, according to the present invention,
While maintaining the 50Ω characteristic of the helical antenna at the time of storage, the impedance characteristic of the helical is moved lower by a metal pipe only at the time of extension, and the whip element is capacitively coupled to it to increase the impedance characteristic again to 50Ω. Can be. By this method,
A quarter-wave helical antenna of 50Ω at the time of storage and a whip antenna (non-contact) of 50Ω at the time of extension can be realized, so that a simple configuration provides good characteristics in both the states of storage and extension.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention. (A) When antenna is stored (b) When antenna is extended

FIG. 2 is a Smith chart showing the frequency characteristics of the antenna impedance of the present invention (a) when the antenna is housed (b) when the antenna is extended

FIG. 3 shows a conventional example. (A) When the antenna is housed (b) When the antenna is extended

FIG. 4 is a Smith chart showing frequency characteristics of antenna impedance in a conventional example. (A) When antenna is stored (b) When antenna is extended

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Transceiver main body 12 Case 13 Case upper surface 14 Projection part 15 Power supply point 21 Helical coil 22 Element 25 Metal pipe (or metal block) 26 Whip element 27 Dielectric rod 32 Dielectric cover 33 Knob part 34 Lower fitting part 35 Upper part Fitting portion

Claims (2)

[Claims] 1. An antenna for use in a portable wireless device in which a transceiver main body is housed in a case, comprising: a helical coil connected to the transceiver main body; An element in which a pipe or a metal block is disposed via a dielectric, and which can be freely drawn and stored in the case, is provided. In the stored state of the element, only the helical coil operates, and in the drawn state of the element, The antenna is characterized in that a metal pipe or a metal block below the element is inserted inside the helical coil, the helical coil itself becomes a low impedance feeding element, and a whip element capacitively coupled to the helical coil operates. 2. An antenna for use in a portable wireless device in which a transceiver body is housed in a case, comprising: a helical coil connected to the transceiver body; An element in which a pipe or a metal block is disposed via a dielectric, and which can be freely drawn and stored in the case, is provided. In the stored state of the element, only the helical coil operates, and in the drawn state of the element, The antenna is characterized in that the metal pipe or metal block below the element is inserted inside the helical coil, the helical coil itself becomes a low-impedance feed element, and a whip element capacitively coupled to the helical coil operates. Portable radio.