JPH0374964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a transmitter antenna for radiating transmitted radio waves from a transmitter into space.

[Technical background of the invention and its problems]

As a conventional transmitter antenna, for example, as shown in FIG. 6, a rod antenna 4 is generally provided outside the transmitter 2. However, since this rod antenna is omnidirectional, the output must be increased if the transmitted radio waves are to be transmitted far. Furthermore, since the antenna has a structure that protrudes from the outside of the transmitter, there are problems in that the antenna is easily damaged due to bending, etc., and is relatively expensive due to its structure. There is also an antenna that is installed inside the transmitter 2 as shown in Figure 7, but in this case the antenna wire 6 is stretched inside the transmitter 2, and like the rod antenna, it has the problem of being non-directional. Ta. Further, there was a problem in that space inside the housing was required in order to extend the wire 6 inside.

[Purpose of the invention]

The present invention was made in consideration of the above circumstances, and
It is an object of the present invention to provide a transmitter antenna that does not require space inside a transmitter housing and has strong directivity with a long radio wave propagation distance.

[Summary of the invention]

In order to achieve the above object, the present invention forms antenna patterns constituting the inductance of a transmission output resonant circuit on the front and back surfaces of a circuit board of a transmitter, respectively.

[Embodiments of the invention]

1 to 5 for one embodiment of the present invention.
This will be explained with reference to the figures. In this embodiment, FIG.
As shown in FIG. 2, a transmitter antenna is constructed by forming loop-shaped patterns 12 and 14 on the front and back surfaces of a circuit board 10 on which a transmitter circuit is formed, respectively. These patterns are formed by etching or the like at the same time as the circuit pattern of the transmitter is formed on the circuit board 10.

This antenna is housed inside a transmitter formed by a base 16 and a front cover 18, as shown in FIG. 3, on a circuit board 10 formed on the front and back surfaces. The base 16 and the front cover 18 are made of plastic, for example. Note that the circuit board 10 is provided with an LED 20 that indicates that the transmitter is in operation, and this LED is placed at a predetermined position on the front cover 18 accordingly.
A hole 22 is provided for the purpose. Further, the front cover 18 is provided with a send button 24.

The output circuit of the transmitter is shown in FIG. The transmission signal input terminal 26 is connected to the base of the transistor Tr via a resistor R1. This transistor Tr
A capacitor C3 is inserted between the base and ground. Further, a resistor R2 and a capacitor C2 connected in parallel are inserted between the emitter of the transistor Tr and the ground. transistor
A trimmer capacitor VC1 and two coils L1 and L2 are connected in parallel and inserted between the collector of the Tr and the power supply voltage _Vcc . The oscillation frequency is determined by the parallel resonant circuit formed by the trimmer capacitor VC1 and the coils L1 and L2.
This embodiment is characterized in that the coils L1 and L2 are formed by loop patterns 12 and 14 formed on both sides of the circuit board 10.

A transmission signal input from the input terminal 22 is amplified by the transistor Tr, and radio waves are radiated into space from the coils L1 and L2 forming a resonant circuit. Patterns 12 and 1 forming these coils L1 and L2
4 are formed on the front and back surfaces of the circuit board 10, it becomes a composite antenna and has directivity as shown in FIG. In other words, this antenna has strong directivity toward the end surface of the circuit board 10.

Note that the loop diameter of this pattern is determined by the oscillation frequency. For example, if the oscillation frequency is 303MHz, the loop diameter will be 10mm.

In this way, according to this embodiment, since the antenna is constructed from the patterns formed on both sides of the circuit board, a separate antenna is not required, which reduces costs and eliminates the need for special space for the antenna. The advantage is that it doesn't.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, the shape of the antenna pattern can be modified in various ways. Note that once the shape of the pattern is determined, its size is determined by the oscillation frequency. Furthermore, the specific configuration of the output circuit of the transmitter can be modified in various ways. For example, the coils L1 and L2 may be connected in series.

〔Effect of the invention〕

As described above, according to the present invention, a transmitter antenna with strong directivity can be provided without requiring any space inside the transmitter. Furthermore, since a separate antenna is not required, costs can be reduced.

[Brief explanation of drawings]

1, 2a and 2b are diagrams showing a transmitter antenna according to an embodiment of the present invention, FIG. 3 is a diagram showing a transmitter having the same transmitter antenna, and FIG. 4 is a diagram showing the same transmitter antenna. FIG. 5 is a diagram showing the directional characteristics of the transmitter antenna, and FIGS. 6 and 7 are diagrams showing the conventional transmitter antenna. 10... Circuit board, 12, 14... Antenna pattern, 16... Base, 18... Front cover, 20... LED, 22... Hole for LED, 24
...Send button.

Claims (1)

[Claims] 1 a circuit board, a first antenna pattern formed on the front surface of the circuit board and forming an inductance of a transmission output resonant circuit, and a first antenna pattern formed on the back surface of the circuit board and forming an inductance of a transmission output resonance circuit; A transmitter antenna comprising a second antenna pattern.