JPH066124A - Transmission antenna - Google Patents

Abstract

PURPOSE:To improve the transmission power of a slave set of a wireless telephone set or the like by adhering a metallic piece to cover a conductor wire to a prescribed position of a transmission antenna wound in a loop. CONSTITUTION:A metallic piece 24 is adhered so as to cover a conductor wire of one or plural sides of an antenna conductor wire 21 being a component of a transmission antenna 20a in antenna conductor wires 21,25 adhered on an insulation plate 23. When the antenna conductor wires 21, 25 are wound in a loop, the antenna directivity being a usual 8-shaped directivity is changed into an omnidirectivity. Since the operating area of a slave set 10 is a circular area around a master set through the omnidirectivity, the operating area of the slave set 10 is remarkably extended than that in the case of the 8-shaped characteristic. The reception sensitivity is improved by properly selecting the size, shape and the adhered position of the metallic piece 24 and the number of the adhered chips and the operating available range of the slave set is almost doubled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting antenna suitable for application to a cordless telephone handset or the like.

[0002]

2. Description of the Related Art A ground plane antenna (whipped antenna), which is a kind of dipole antenna, is generally used as a transmission / reception antenna for both transmission and reception equipped in a low power cordless telephone. The whip antenna is composed of a radiator (conductor wire) protruding outside the telephone housing and a counterpoise conductor wire housed in the housing. This configuration is the same for both the master unit and the slave unit.

The frequency band permitted to be used in cordless telephones has a transmission frequency of 380 MHz in the base unit,
The reception frequency is in the 254 MHz band, and in the slave unit, the transmission frequency is in the 254 MHz band and the reception frequency is 380 MHz.
Since it is a band, if a radiator having a length of λ / 4 (λ is a wavelength) is used, the length becomes considerably long. Therefore, for example, in the slave unit, as shown in FIG. 7, a part of the normal transmitting / receiving antenna 20 is provided so as to partially protrude (about 10 to 20 cm) outside the slave unit housing 11.

In FIG. 7, reference numeral 12 is a receiver and 13 is a transmitter.

[0005]

The slave unit may be used both indoors and outdoors. At that time, the transmitting / receiving antenna 20 provided in the child device may be damaged during use or during transportation. In order to avoid this, the radiator 26 of the transmitting / receiving antenna 20 may be housed in the housing 11. However, it is technically difficult to store the radiator 26 due to the size and shape of the housing 11.

There is a loop antenna as a transmission / reception antenna 20 on the side of the handset which can be considered there. Even if a loop antenna is used, it cannot be stored in the housing in one turn. If you use this by winding it for several turns, it can be stored sufficiently even if the storage space is small.

[0007] However, it was confirmed that the transmission capability of the antenna characteristics is remarkably reduced when the loop-like configuration is used. According to the experiment, the transmission capability (transmission power) was reduced to about 1/2.

[0008] This means that the usable range of the handset becomes 1/2 or less, so that when the ordinary cordless telephone is used, the usable distance falls to 50 m or less. However, since the antenna characteristic changes from the original figure-eight directivity to omnidirectional, there is an advantage that the usage area as a slave is not limited.

Therefore, the present invention proposes a transmitting antenna in which a transmitting antenna and a receiving antenna are separately provided, and in particular, the transmitting ability is not deteriorated even if the radiator for the transmitting antenna is housed in a housing.

[0010]

In the present invention, a metal piece is attached to a predetermined portion of a transmitting antenna in which a conductor wire used as an antenna wire is wound in a loop so as to cover the conductor wire. It is characterized by that.

[0011]

As shown in FIGS. 1 and 2, the transmitting antenna 2
Both 0a and the receiving antenna 20b are completely housed in the housing 11. Conductor wires 2 each having a length of approximately λ / 4
N turns, m so that 1 and 25 have a substantially hollow rectangular shape.
It is wound around a turn and stored in the housing 11.

A metal piece 24 is attached to one side of the looped conductor wire 21 which constitutes the transmitting antenna 20a. In such a case, the transmission ability before and after attaching the metal piece 24 is 2.
It was improved to about 5 dBm.

Therefore, the housing 1 is formed into a loop antenna.
Even when the transmission / reception antenna 20 is housed in 1, the transmission capability can be improved, so that the usable distance between cordless telephones can be the same as the conventional one.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a case where an example of a transmitting antenna according to the present invention is applied to a low power cordless telephone will be described in detail with reference to the drawings.

When applied to a cordless telephone, the reception frequency used in the slave unit is the 380 MHz band,
Since the transmission frequency band is the 254 MHz band, separate transmission antennas and reception antennas are used.

FIG. 1 shows a case in which the present invention is applied to a mobile device 10, and a transmission antenna 20a and a reception antenna 20b are housed in a part of a housing 11 thereof. The transmitting antenna 20a will be described. This is as shown in FIG.
Is selected to be λ / 4 (λ is a wavelength) or a length obtained by multiplying this by a shortening rate, and is wound into a rectangular loop so as to have a predetermined inner diameter. The figure is wrapped in an elongated loop. The outer diameter is determined by the size of the housing 11 in which it is stored, the storage space, and the like.

When the outer diameter of the loop is determined, the number n of antenna turns is determined. It is also possible to select a predetermined number of turns n in advance and then select the place where the antenna is to be housed.

The loop-shaped transmitting antenna 20a is shown in FIG.
As shown in B, it is attached on an insulating plate 23 having a predetermined thickness. The receiving antenna 20 is provided on the other surface side of the insulating plate 23.
The antenna conductor wire 25 constituting b is attached.

In the present invention, among the antenna conductor wires adhered on the insulating plate 23 as described above, particularly the transmitting antenna 2 is used.
The metal piece 24 is attached to one side or a plurality of sides of the antenna conductor wire 21 forming 0a so as to cover the conductor wire of the side.

FIG. 2A shows a part of the upper side of the conductor wire 21 in the winding direction, and the width direction (direction orthogonal to the winding direction) covers the whole conductor wire. The metal piece 24 is attached to.

Although the shape and size of the metal piece 24 will be described later, a foil piece having a thickness of about 0.1 mm can be used.

On the front and back of the insulating plate 23, the antenna conductor wire 21,
Instead of attaching 25, the antenna conductor wires 21 and 25 may be attached to separate insulating plates 23. The metal piece 24 can be made of a metal material such as iron, aluminum, or copper.

When the antenna conductor wires 21 and 25 are wound in a loop shape, the antenna directivity changes from the normal figure-eight directivity to omnidirectional. Due to the non-directionality, the use area of the child device 10 becomes a circular shape centering on the parent device, so that the use area is greatly expanded as compared with the case of the figure 8 characteristic.

A metal piece 24 attached to the antenna conductor wire 21
The antenna characteristics change depending on the size, shape, attachment position, number of attachments, etc. How the antenna characteristics change with these variables will be described below. As its premise, the transmission frequency is 254 MHz, the transmission antenna 20a
The distance from the transmitting antenna 20a to the receiving power measuring device is 1.8 m, the ground height of the transmitting antenna 20a and the measuring device is 1 m, and the transmitting power is 8 mW.

An example of measuring the receiving sensitivity under such conditions is shown in FIGS. 3 and 5. FIG. 3 shows a measurement example when the metal piece 24 is attached so as to cover the entire surface of the antenna conductor wire 21 as shown in FIG. The metal piece 24 used is an iron foil and has a thickness of 0.1 mm. The result is as follows. (A) FIG. 3A Metal piece 24 ... Receiving power without pasting ... 29 dBm (B) FIG. 3B Metal piece 24 ... 34 mm long, 24 mm wide Sticking position ... Upper side Receiving sensitivity --26.5 dBm (C) FIG. 3C Metal piece 24 ... 20 mm long, 24 mm wide Adhesion position ... Upper side Receiving sensitivity ... --27 dBm (D) 3D metal piece 24・ ・ ・ Vertical 32 mm, horizontal 20 mm Sticking position ・ ・ ・ Upper side Reception sensitivity ・ ・ ・ -27 dBm (E) Fig. 3E Metal piece 24 ・ ・ ・ Vertical 42 mm, horizontal 42 mm Sticking position ・ ・ ・ Left and right Since the receiving sensitivity is −27.5 dBm or more, when the metal piece 24 is attached, the receiving sensitivity is improved by 2.0 to 2.5 dBm. This means that the transmission capability of 20a is improved. Therefore, the transmission capability is almost twice as large as when the metal piece 24 is not attached, and the usable distance of the child device (radio wave reach) can be almost doubled.

The metal piece 24 shown in FIG. 2 is the antenna conductor wire 2
Although it is an example of sticking so as to surround the entire surface of No. 1, it is also possible to stick so as to cover only the surface side thereof as shown in FIG.

FIG. 5 shows an example of measurement when copper foil is used instead of iron foil as the metal piece 24 used. The measurement conditions are the same. (A) Fig. 5A Metal piece 24 ... vertical 34 mm, horizontal 24 mm Sticking position ... upper side Receiving sensitivity ... -26.5 dBm (B) Fig. 5B Metal piece 24 ... vertical 20 mm, Horizontal 24mm Adhesion position ... Upper side Reception sensitivity ...- 27.0 dBm (C) Fig. 5C Metal piece 24 ... Vertical 42mm, Horizontal 20mm Adhesion position ... 2 places on both left and right sides Receiving sensitivity ・ ・ ・ -26.5 dBm In this case as well, it is 2 to 2.5 dB, which is almost the same as the iron foil.
The improvement of m was seen. Therefore, it can be seen that the material, size, shape, and the like of the metal piece 24 do not depend so much.

FIG. 6 shows a modified example of FIG. 5A in which the surface of the antenna conductor wire 21 is covered as shown in FIG. 4 and iron foil is used instead of copper foil. At this time, the metal piece 24 ... 17 mm in length, 24 mm in width Adhesion position ... Upper side Receiving sensitivity ...- 27.5 dBm, so that the metal piece 24 covers the entire antenna conductor wire 21. It can be seen that the transmission capability can be improved by doing so.

It should be noted that such a metal piece is not attached to the receiving antenna 20b. This is because it was confirmed by experiments that the reception sensitivity is lowered when this is attached.

The present invention can be used not only as a cordless telephone but also as a transmitting antenna for personal or business transceivers.

[0031]

As described above, in the present invention, the metal piece is attached so as to cover a part of the conductor wire of the transmitting antenna wound in a loop.

According to this, since the transmission power is more than doubled as compared with the case where no metal piece is attached, the area where radio waves reach is greatly expanded. Therefore, when it is applied to a cordless telephone or the like, it has a feature that the range of use of the handset can be expanded.

[Brief description of drawings]

FIG. 1 is a diagram of a slave unit to which a transmitting antenna according to the present invention is applied.

FIG. 2 is a diagram showing an example of a transmission antenna.

FIG. 3 is a diagram showing an example of reception sensitivity measurement.

FIG. 4 is a sectional view of a main part showing another example of a transmission antenna.

FIG. 5 is a diagram showing an example of measurement of reception sensitivity.

FIG. 6 is a diagram showing an example of reception sensitivity measurement.

FIG. 7 is a diagram of a slave unit using a conventional antenna.

[Explanation of symbols]

 10 Telephone (slave unit) 20 Transmission / reception antenna 20a Transmission antenna 20b Reception antenna 21,25 Antenna conductor wire 24 Metal piece

Claims (1)

[Claims] 1. A transmitting antenna, wherein a metal piece is attached to a predetermined portion of a transmitting antenna in which a conductor wire used as an antenna wire is wound in a loop so as to cover the conductor wire.