JPH0432305A - Antenna - Google Patents

Abstract

PURPOSE:To realize the antenna with excellent portability with simple structure by forming the antenna with a specific telescopic conductor pipe and a matching part connecting to one end of the conductor pipe. CONSTITUTION:The antenna consists of a telescopic conductor pipe 1 and a matching part 2 connecting to one end of the pipe 1. The conductor pipe 1 comprises three kinds of pipe whose diameters differ from each other, and the length of the pipe 1 is nearly 1/2 wavelength when the telescopic pipe is fully stretched and the length of the pipe 1 is nearly 1/4 wavelength or below when the telescopic pipe is fully drawn in. Since the impedance of the pipe 1 at the length of nearly 1/2 wavelength is almost equal to the impedance of the pipe 1 at the length of 1/4 wavelength or below, the matching is taken by using a common matching circuit independently of the length of the pipe 1, then power radiates effectively from the antenna. Thus, the antenna with excellent portability with simple structure is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antenna, and particularly to an antenna for use in a portable radio device.

[Conventional technology]

Conventionally, a whip antenna having a length of about 1/2 wavelength has been used in portable radio equipment. This is because the gain in the horizontal plane is relatively high (approximately 0 dBd), and it has the advantage that there is almost no decrease in gain due to the human body even if the portable device approaches the human body during a call.

[Problem to be solved by the invention]

The conventional 1/2 wavelength antenna mentioned above has an element length of 1/2 wavelength.
Since it has two wavelengths and is long, it has the disadvantage of poor portability. In order to eliminate this drawback, a portable radio device having a structure in which a 1/2 wavelength antenna can be housed within the housing has been considered. However, this case had the disadvantage that it would no longer function as an antenna if it was stored while being carried.

Furthermore, in order to prevent other portable radios from ceasing to function as an antenna when a 1/2 wavelength antenna is stored, a separate built-in antenna is provided, and the antenna can be switched when the 1/2 wavelength antenna is stored. The solution was to activate the built-in antenna. however,
This method has the disadvantage that the structure becomes complicated and the volume of the portable radio becomes large due to the provision of the built-in antenna.

SUMMARY OF THE INVENTION An object of the present invention is to provide an antenna for a portable radio device that eliminates the seven or more drawbacks of conventional 1/2 wavelength antennas for portable radio devices.

[Means to solve the problem]

- In order to achieve the above object, the antenna of the present invention includes an expandable conductor tube having a length of approximately 1/2 wavelength when expanded and 1/4 wavelength or less when shortened, and a matching conductor tube connected to one end of the conductor tube. It is characterized by consisting of parts.

More preferably, the length of the conductor tube is about 0.17 m when extended and about 0.1045 m when shortened.

[Effect]

With the above configuration, the portable radio antenna can be extended and used as a 1/2 wavelength state, or it can be shortened to 1/2 wavelength state.
The antenna can also be used in a state where the wavelength is less than /4 wavelength, and the antenna can be used in two types of states as described above.

〔Example〕

Next, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a perspective view showing the antenna of the present invention.

In the figure, reference numeral 1 denotes an expandable conductor tube, and a matching portion 2 connected to the conductor tube forms an antenna.

This conductor tube 1 is composed of three tube bodies with different diameters, and when stretched, it has a length of about 1/2 wavelength.
When shortened, the length becomes less than 1/4 wavelength. In addition, 3 in the figure
is the power supply section.

By setting the conductor tube 1 to a predetermined length of approximately 1/2 when extended and 1-/4 or less when shortened, the impedances are set approximately equal, so matching is performed by a common matching circuit (matching section 2 ), the power can be radiated more efficiently than the antenna.

FIG. 2(a) is a perspective view of the antenna of the present invention attached to the portable radio device housing 5. This antenna 4 is made up of rondos, with an extended length of 0.17 m and a shortened length of 0.04 m.
It is made of 5 meters.

FIG. 2(b) shows the return loss characteristics of the antenna of the present invention when it is extended and when it is shortened. It can be seen from this that matching is achieved both during expansion and contraction.

FIG. 2(e) shows the directivity of the antenna of the present invention when it is extended.
Figure (d) shows the directivity when shortened. It can be seen that when expanded, the characteristics are equivalent to those of the conventional -72 wavelength antenna. It can be seen that when shortened, the characteristics in the horizontal direction are equivalent to a 1-/2 wavelength antenna.

Comparing the directional characteristics of the antenna of the present invention when shortened with the characteristics of the -/4 shortened helical whip attached to the portable device shown in Fig. 3(a), it can be seen that they are comparable ( Figure 3(b)).

〔Effect of the invention〕

As explained above, in the present invention, when stretched, approximately 1/2 wavelength,
The antenna is constructed from an expandable conductor tube whose length is 1/4 wavelength or less when shortened, and a matching part connected to one end of the conductor tube, which has a simple structure and excellent portability. On the other hand, power is efficiently radiated in the horizontal plane whether the conductor tube is extended or shortened, and the power is approximately 0 dBd.
This has the advantage of being able to provide an antenna that can provide a relatively high gain.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, and FIG.
) is a perspective view showing the usage state of the example, FIG. 2(b) is a graph showing the return loss characteristics of the example, and FIG. 2(c) and (d) are graphs showing the directivity characteristics of the example. , Figure 3(,) is a perspective view of a conventional type ]/4 telescopic helical whip attached to a portable device, Figure 3(b)
is a graph showing its directional characteristics. 1: Conductor tube 2: Matching section 3: Power feeding section 4; Antenna 5: Portable radio device housing

Claims (2)

[Claims] (1) An antenna comprising an expandable conductor tube that has a length of about 1/2 wavelength when expanded and 1/4 wavelength or less when shortened, and a matching section connected to one end of the conductor tube. (2) Claim characterized in that the length of the conductor tube is approximately 0.17 m when extended and approximately 0.045 m when shortened.
1) The antenna described.