JPS5930305A - Rod antenna device - Google Patents

Abstract

PURPOSE:To attain excellent operation even at a high frequency band, by constituting the device that a monopole element and a ground side element are parted. CONSTITUTION:The lowermost element among shrinkable and contractable elements is split into two, the upper and the lower parts. The upper part element 14a1 and the lower part element 14a2 are coupled through an insulator 15 so that they are slidable freely into/from the inside of a fixed element 17 as a 16 is fitted to the lowermost part of the element 14a2 and it is held with the fixed element 17. A coaxial cable 20 is inserted into the inside of the element 14a2 from the lower side. An inner conductor 21 of the inserted cable 20 is connected to the element 14a1 and an outer conductor 22 is connected to the element 14a2. The element 14a2 is operated as the ground side element in the construction above and the element 14a1 is connected to the other elements and acts like a monopole element.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electric telescoping rod antenna device suitable for vehicle use in the VHF-UHF band for use in television receivers, various radio devices, etc. It is something.

Conventional Structure and Its Problems An example of the structure of a conventional vehicle-mounted electric telescopic rod antenna device is shown in FIGS. 1 and 2. Note that FIG. 2 is an enlarged sectional view of the portion surrounded by the dotted line in FIG. 1. To explain this, the elements 1a and 1 of the rod antenna that expand and contract.
b...The lowest element 1a among 11 is
It is held by a metal fixing element 3 via an insulator 2. This fixing element 3 is fastened and connected to the vehicle body 5 by a metal fitting 4 and is held therein. The lowermost element 1a has a structure in which it comes into contact with a contact spring 8 connected to an internal conductor 7 of a coaxial connector 6. The lowest part 9 of the lowest element 1a is a stopper, and the contact spring 8
It has a structure that prevents it from falling out.

In addition, element 1. A flexible wire 10 is connected to the element 1a of the rod antenna.

1b... Plays the role of expanding and contracting 1i.

Page In a rod antenna device with such a structure, since the lowest element 1a and the fixed element 3 are close to each other, there is a large capacitance between them, and as shown in Figure 3, there is a large capacitance between the antenna element and the ground. There will be a large capacitance C between them. Low frequency band 1 For example, FM band (76~
works well in high frequency bands 9 such as VHF television bands (90-222) and UHF
In the television band (470 to 770i), the capacitance between the antenna base and the ground is large, so even if the length of the element is changed, it does not function as an antenna at all.

OBJECTS OF THE INVENTION The present invention aims to overcome the drawbacks of the two conventional examples and provide a rod antenna device that operates well even in high frequency bands.

Composition of the Invention The rod antenna device of the present invention has a structure in which the lowermost element of a telescoping rod antenna is divided into two by a varnish via an insulator, and integrated into a fixed element so that it can be freely moved in and out. A flexible wire for expanding and contracting the Shirorad antenna element is passed through the inside of the lowermost element of the rod antenna by a motor, and a coaxial cable is inserted from the bottom of the lowermost element of the rod antenna. is inserted, the upper element constituting the lowest element of the rod antenna is connected to the inner conductor of the coaxial cable, and the lower element is connected to the outer conductor of the coaxial cable. .

DESCRIPTION OF EMBODIMENTS The present invention will be explained below based on the embodiments shown in FIGS. 4 and 6. Note that FIG. 5 is an enlarged sectional view of the portion surrounded by the dotted line in FIG. 4. In those figures, a telescoping element 14a.

14b...The lowest element 1 of 141
4a is divided into upper and lower halves as shown by 14a1 and 14a2. This upper element 14a1 divided into two
and the lower element 14a2 are combined via an insulator 16 inserted inside them, and move in and out of the metal fixed element 17 in conjunction with the flexible wire 21 as an integral knee page element 14a. It has a structure that allows it to slide freely. At the bottom of the element 14a2 below the element 14a is a contact spring/stopper 16.
is attached and held by a fixing element 17. The fixing element 17 is held connected to the vehicle body 19 by means of a fastening fitting 18. The coaxial cable 2o is inserted into the fixed element 17, and the lower element 14 of the lowermost telescopic element 14a
A coaxial cable 2o is inserted into the inside of a2 from below. The inner conductor 21 of the inserted coaxial cable 2o is
The outer conductor 22 is connected to the upper element 14a1 of the lowermost element 14a, while the outer conductor 22 is connected to the lower element 14a1.
Connected to a2. In such a structure, when the lowermost element 14 is stretched by the flexible wire 10, the lower element 14a2 of the nilayment 14a
is fixed element 17. The clamp is connected to the car body 19 via a metal fitting 18, and is connected to the earth side elm 6 of the monoball antenna.

vane Works as a ment.

On the other hand, the upper elements 14° of the elements 14 are elements 14b...14. and operates as a monopole element with element length ρ.

On the other hand, elements 14a, 14b,...14□
can be stored inside the fixing element 17.

When the antenna is not in use, it has a structure that hardly protrudes from the car body 9, making it convenient to use.

Effects of the Invention As is clear from the above explanation, the rod antenna device of the present invention has a first
Unlike the conventional example shown in the figure, they are not arranged closely and do not have large capacitance, so they operate well up to high frequency bands of VHF and UHF bands, and are extremely effective in practice.

[Brief explanation of drawings]

Figure 1 is a front view of a conventional electric telescoping rod antenna device for vehicles, Figure 2 is an enlarged sectional view of the main parts of Figure 1, and Figure 3
The figure is a schematic diagram for explaining the operation of the Rondo antenna device in Figure 1, Figure 4 is a partially cutaway front view of an embodiment of the present invention, and Figure 5 is an enlarged sectional view of the main part of Figure 4. be. 1o... Flexible wire, 11...
Rod antenna drive motor, 14a, 14b...
・・・１４□・・・Extensible element, １５・
... Insulator, 17 ... Fixed element,
18...Tighten the metal fittings, 19...Car body, 2o...Coaxial cable. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4 Figure 14/; ! Pigeon/4 m 1 /61 5 1 1 fq 11θI ■ 1 1 1 // 1 ) π −” 2 @ l?

Claims (1)

[Claims] The lowermost element of the retractable rod antenna is divided into upper and lower parts via an insulator, and is integrated into a structure that can be accommodated in and out of the fixed element. A coaxial cable is inserted through a flexible wire for expanding and contracting the element of the rod antenna by a motor and from below the lowermost element of the rod antenna, thereby forming the lowermost element of the rod antenna. A rod antenna device characterized in that an upper element is connected to an inner conductor of the coaxial cable, and a lower element is connected to an outer conductor of the coaxial cable.