JPH01101702A - Radiocommunication equipment - Google Patents

Abstract

PURPOSE:To prevent an antenna effect from being lowered even when an antenna is retracted by connecting a loading coil, whose inductance is small, to the antenna when a telescopic antenna is expanded and connecting a loading coil, whose inductance is large, to the antenna when it is retracted. CONSTITUTION:A telescopic antenna 2 is provided. Then, switches 3a and 3b are provided to connect a loading coil 8, whose inductance is small when the antenna 2 is expanded, to the antenna 2 and to connect a loading coil 9, whose inductance is large when the antenna 2 is retracted, to the antenna. Accordingly, even when the antenna 2 is expanded and retracted, an antenna circuit is oscillated with a transmitting and receiving radio wave. Thus, a radiocommunication equipment, in which there is no extreme difference to the sensitivity of the antenna even when the antenna is expanded and retracted and a high frequency output transistor is not destroyed even when transmission is executed in a condition that the antenna is retracted, can be obtained.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a wireless communication device.

Conventional technology Traditionally, portable wireless communication devices such as cordless telephones and transceivers have sometimes used expandable antennas. Shrink the antenna. During communication, the antenna is extended to improve the antenna effect. The length of the antenna to obtain the best antenna effect is a length corresponding to 1/4 wavelength of the transmitted and received radio waves. However, if the length is set as above, the antenna will be very long (and it will be inconvenient to carry for a portable wireless communication device) if the frequency of the transmitted and received radio waves is low.
In such a case, the loading coil is connected to an antenna shorter than 1/4 wavelength of the transmitted and received radio waves, so that the length of the antenna equivalently corresponds to 1/4 wavelength of the transmitted and received radio waves.

Problems to be Solved by the Invention However, in the above configuration, the loading coil is set so that the antenna is extended so as to obtain the best antenna effect, that is, to resonate with the transmitted and received radio waves. When the portable special antenna is retracted, the resonant frequency of the antenna circuit shifts, making it impossible to obtain a sufficient antenna effect. was.

Additionally, the impedance of the antenna circuit changes dramatically between when the antenna is extended and when it is retracted, so transmitting with the antenna retracted could damage the transistors in the transmitter circuit.

The present invention has been made in view of the above-mentioned conventional technology, and there is no significant difference in antenna sensitivity when the antenna is extended or retracted, and the high-frequency output transistor is damaged even when transmitting with the antenna retracted. It provides a wireless communication device that does nothing.

Means for Solving the Problem In order to achieve this object, the wireless communication device of the present invention has an extendable antenna and a loading coil that has a small inductance when the antenna is extended, and a loading coil that has a small inductance when the antenna is contracted. has a switch that connects the large loading coil to the antenna.

Effect With this configuration, when the antenna is retracted, a loading coil with large inductance is connected to the antenna, and when the antenna is extended, a loading coil with small inductance is connected to the antenna, so that the antenna circuit can transmit and receive regardless of whether the antenna is extended or retracted. Resonates with radio waves.

Embodiment Hereinafter, an embodiment of the wireless communication device of the present invention will be described using a cordless telephone as an example with reference to the drawings.

FIG. 1 is a side sectional view of a cordless telephone according to an embodiment of the present invention with the antenna retracted, and FIG. 2 is a front view of the same. Further, FIG. 3 is a side sectional view with the antenna extended, and FIG. 4 is a front view thereof. FIGS. 5 and 6 are block diagrams showing the configuration of the main parts. In FIGS. 1 to 4, 1 is a cabinet, and 2 is an antenna which is extendable and slidably attached to the cabinet 1.

A switch 3 is attached to the bottom of the cabinet 1 and operates in response to expansion and contraction of the antenna 2. Further, the switch 3 has two contacts 3a and 3b, and when the antenna 2 is contracted, the contact 3a is opened, and when the antenna 2 is extended, the contact 3b is opened. 4 is a dial button, 5 is a microphone, 6 is a send button, and 7 is a speaker.

8 is an inductance set such that a particularly good antenna effect can be obtained by extending the antenna 2 with the first loading coil. 9 is the second loading coil, and the inductance is set so that the best antenna effect can be obtained when the antenna 2 is contracted. 10 is a receiving section;
A receiving amplifier 11 amplifies the audio signal received by the receiving section 10 and outputs it to the speaker 7. A modulator 12 amplifies and modulates the audio signal input from the microphone 5, and outputs the modulated signal to the transmitter 13. Reference numeral 14 represents a control means for controlling the entire system. 15 is a calling signal generating means, and 16 is a calling signal generating speaker.

The cordless telephone configured as described above is used in pair with a base unit connected to a telephone line, and its operation will be explained below. Here, the base unit may be a common one, so its explanation will be omitted.

First, in order to transmit from the cordless phone side, antenna 2
When extended, the lower end of the antenna 2 is pulled up as shown in FIG. 3, and the button of the switch 3 is pushed up by a spring (not shown) inside the switch 3. As a result, as shown in FIG. 6, the contact 3a of the switch 3 becomes conductive and the contact 7b becomes non-conductive. Therefore antenna 2
When extended, the loading coil 9 is connected to the antenna 2, the receiving section 10, and the transmitting section 13. Here, the inductance of the loading coil 9 is set to such a value that it resonates with the transmitted and received radio waves when the antenna 2 is extended.

When the transmit button 6 is pressed here, the control means 14 transmits the transmitter 1
A control signal is output to 3 to control the telephone line closing signal to be sent to the base unit. The high frequency signal output from the transmitter 13 is transmitted to the first loading coil 8 and the contact 3 of the switch 3.
a, and is transmitted as a radio wave from the antenna 2. The radio waves transmitted from the cordless phone are received by the base unit's antenna. This causes the base unit to close the telephone line. After this, when the dial button 4 is pressed and a dial signal is sent out, the base unit sends out the dial signal to the telephone line and can talk to the other party.

When the call state is completed, the audio signal input from the microphone 5 of the mobile device 1 is amplified and modulated by the modulation section 12 and sent to the transmission section 13.
is output to. The high frequency signal output from the transmitter 13 passes through the contact 3a of the loading coil 8 switch 3 and is transmitted from the antenna 2.

Next, when carrying the cordless telephone, the antenna 2 should be retracted as shown in Figures 1 and 2 and placed in the cabinet 1.
Push it inside so it doesn't get in the way. In this state, the switch button is pressed in by the lower end of the antenna 2, as shown in FIG. Therefore, as shown in FIG. 5, the contact 3b of the switch 3 is in a conductive state, the contact 3a is in a non-conductive state, and the second loading coil 9 is connected to the antenna 2, the receiving section 10, and the transmitting section 13. Here, the inductance of the second loading coil 10 is set to a value that resonates with the transmitted and received radio waves when the antenna 2 is retracted.

When the antenna 2 is in the contracted state 1, when a radio wave is transmitted from the base unit, the antenna 2 and the second loading coil resonate with the radio wave transmitted from the base unit, and the receiving means 9 receives the transmitted radio wave. receive. Then, the control means 14 controls the calling signal generating means 15 to cause the calling signal generating speaker 16 to generate a ringing tone. The user listens to the calling signal emitted from the speaker 16 and extends the antenna 2. When the send button 6 is pressed, the transmitting section 13 outputs a signal instructing the base unit to close the telephone line, and the base unit closes the telephone line and enters a talking state.

Even when the antenna 2 is retracted as described above, the antenna 2 resonates the radio waves emitted by the base unit, so the sensitivity does not decrease much.

Effects of the Invention As described above, the present invention provides an expandable antenna and a switch that connects a loading coil with a small inductance to the antenna when the antenna is extended, and connects a loading coil with a large inductance to the antenna when the antenna contracts. Because of this, even when the antenna is retracted, the antenna effect does not decrease much, and it is possible to receive calling signals from other wireless communication devices within the same range as when the antenna is extended. Furthermore, even when transmitting with the antenna retracted, the output transistor of the transmitting circuit will not be damaged.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view of a cordless telephone in an embodiment of the wireless communication device of the present invention with the antenna retracted, FIG. 2 is a front view of the same, and FIG. 3 is a side view of the cordless telephone with the antenna extended. FIG. 4 is a sectional view, FIG. 4 is a front view of the same, and FIGS. 5 and 6 are block diagrams showing the configuration of the main parts. 1... Cabinet 2... Antenna 3... Switch 4... Dial button 5... Microphone 6... Transmission button 7... Speaker 8... First loading coil 9... Second loading coil 10... Receiving section 11... Receiving amplifier 12... Modulating section 13... Transmitting section 14... Control means 15... Calling signal generating means 16... Calling signal generation Name of speaker agent: Patent attorney Toshio Nakao and one other person Figure 1
Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] An extendable antenna, a plurality of coils each having a different inductance, and a coil that operates according to the expansion and contraction of the antenna and has a small inductance when the antenna is extended, and a coil that has a large inductance when the antenna is contracted. A wireless communication device characterized by comprising a changeover switch for connecting the antenna to the antenna.