JP3174690B2 - Radio antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio antenna capable of obtaining two kinds of antenna characteristics by simple operation without replacing the antenna.

[0002]

2. Description of the Related Art Conventionally, as an example of a radio antenna,
A coil antenna having an effective length of 1/4 wavelength is fixedly provided so as to protrude outward from the housing of the wireless device.
Some include a rod antenna having an effective length of two wavelengths. As one example, the technique described in Japanese Patent Application Laid-Open No. 2-271701 discloses a technique in which a base end of a coil antenna is electrically connected to a transmission / reception circuit of a wireless device, a rod antenna in a housed state is insulated from the coil antenna, The rod antenna in the pulled-out state has a structure in which the base end is capacitively and electrically connected to the tip end of the coil antenna.

[0003]

In the above-mentioned prior art, the state where only the coil antenna functions as an antenna by storing or pulling out the rod antenna is described.
Two types of antenna characteristics in a state where both the coil antenna and the rod antenna act as antennas can be obtained by a simple operation. However, in the state where the rod antenna is pulled out, the coil antenna and the rod antenna are electrically connected in a two-stage stack, so that they function as one antenna, and it is difficult to adjust the antenna characteristics. In addition, since the electrical connection between the coil antenna and the rod antenna depends on the coupling capacitance, a change in the coupling capacitance causes a remarkable change in the antenna characteristics, and the characteristics are not stable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances of the related art, and two types of antenna characteristics can be easily obtained by storing and pulling out a rod antenna, and the antenna characteristics are stable. The purpose is to provide.

[0005]

In order to achieve the above object, an antenna for a radio device according to the present invention has a coil antenna fixedly disposed so as to protrude outward from a housing of the radio device, and the coil antenna is mounted on an axis. A rod antenna is disposed so as to penetrate in the direction of the wireless device and can be housed and pulled out of the housing of the wireless device, a base end of the coil antenna is electrically connected to a transmitting / receiving circuit of the wireless device, and a base end of the rod antenna in a pulled-out state. Is electrically connected to the transmitting and receiving circuit through a matching circuit, and furthermore, the matching circuit is set such that the input / output impedance of the matching circuit and the input / output impedance of the coil antenna match in a state where the rod antenna is pulled out, When the rod antenna is stored, the rod antenna is electrically connected only to the coil antenna without being electrically connected to the transmitting / receiving circuit. Wherein is configured such that the at extended state of the rod antenna aligned coil antenna and the rod antenna is electrically connected to the transceiver circuit in parallel.

The housing is provided with a mounting nut made of a conductive material provided with a female screw for communicating the inside and the outside of the housing, and a bobbin made of an insulating material around which the coil antenna is wound is provided at the lower end thereof. The mounting nut is made detachable by screwing, the base end of the coil antenna is electrically connected to the mounting nut when the bobbin is mounted, and the mounting nut is electrically connected to the transmission / reception circuit. The rod antenna is penetrated through a through-hole provided in the bobbin in the axial direction so that the rod antenna can be housed and pulled out, and a feeding spring made of a conductive material provided in the housing at the base end of the rod antenna in the pulled-out state is electrically connected. The power supply spring may be electrically connected to the transmitting / receiving circuit via the matching circuit.

[0007]

[Operation] In the stowed state of the rod antenna, only the coil antenna is directly electrically connected to the transmission / reception circuit to perform the antenna function. When the rod antenna is pulled out, the coil antenna is electrically connected to the transmission / reception circuit, and the base end of the rod antenna is electrically connected to the transmission / reception circuit via the matching circuit in parallel with the coil antenna. Therefore,
Both the coil antenna and the rod antenna have an antenna function as respective antennas. Moreover, a matching circuit is connected to the base end of the rod antenna, so that the input / output impedance of the coil antenna and the input / output impedance of the matching circuit with the rod antenna pulled out are the same. Signals can be transmitted efficiently.

If the bobbin around which the coil antenna is wound is made detachable by screwing into a mounting nut provided on the housing, the rod antenna, the coil antenna, etc. are damaged, and the antenna characteristics are abnormal. In that case, the antenna can be easily replaced without opening the housing.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIGS. 1A and 1B are longitudinal sectional views of an embodiment of a radio antenna according to the present invention, in which FIG. 1A shows a state where a rod antenna is pulled out, and FIG. . FIG. 2 is an external side view of the radio antenna shown in FIG. 3A and 3B show the holding bracket of FIG. 1, wherein FIG. 3A is a side view, and FIG.
It is a sectional arrow view. 4A and 4B are equivalent circuit diagrams of the wireless device antenna shown in FIG. 1, wherein FIG. 4A shows a state where the rod antenna is pulled out, and FIG. 4B shows a state where the rod antenna is housed.

In the drawing, a mounting nut 12 made of a conductive material is press-fitted and fixed in a hole of a housing 10 of the wireless device. The mounting nut 12 is formed with a flange portion for restricting insertion into the outside of the housing 10, a lower end portion is protruded into the housing, and a female screw for communicating the inside and outside of the housing 10 in the axial direction is engraved. You. The bobbin 14 made of an insulating material is provided with a male screw which is screwed into a female screw of the mounting nut 12 at the lower end. A coil antenna 16 having an effective length of 1/4 wavelength is wound around the outer periphery of the bobbin 14, and its base end is electrically connected to a power supply fitting 18 screwed to a male screw by soldering or the like.
Further, a cover 20 made of an insulating material is covered so as to cover the bobbin 14 and the power supply fitting 18, and is appropriately fixed. The bobbin 14 and the cover 20 pass through holes in the axial direction. In addition, a female screw is formed at the lower end of the through hole. Then, a male screw provided at the upper end of a holding member 22 made of an elastic conductive material is screwed into the female screw of the through hole, and the holding member 22 is fixed to the bobbin 14. The holding bracket 22 is provided with a through-hole communicating with the through-hole of the bobbin 14, and as shown in FIG.
A plurality of slits are provided from the center to the lower end so that the lower end from the center can be elastically deformed in the radial direction.

A tube 26 made of an insulating material is placed over the rod antenna 24 having an effective length of 1/2 wavelength. A sleeve 2 is attached to the tip of the rod antenna 24.
8 is fixed, and a cap 30 is attached to the sleeve 28.
Is fixed. Further, the rod antenna 24 is connected to the bobbin 1
A stopper 32 made of a conductive material is fixed to the base end portion of the cover 4 through the through hole of the cover 20, the holding member 22, and the through hole. The outer diameter of the stopper 32 is set to a size that can be fitted into the through hole of the holding fixture 22 and can be held elastically. Further, a flange-shaped large-diameter portion is formed at the lower end of the stopper 32, so that the rod antenna 24 is prevented from coming off toward the distal end. The outer diameter of the sleeve 28 provided at the distal end of the rod antenna 24 is set to a size that can fit into the through hole of the bobbin 14.

Further, a power supply lug 34 made of an elastic conductive material is appropriately fixed so as to elastically contact the outer periphery of a lower end portion of the mounting nut 12 protruding into the housing 10, and the power supply lug 34 is wirelessly connected to a lead wire. It is electrically connected to a transmission / reception circuit (not shown) of the machine. In addition, a power supply spring 36 made of an elastic conductive material is appropriately fixed so as to elastically contact the outer periphery of the lower end portion of the holding bracket 22, and this power supply spring 36 is connected to one input / output terminal of the matching circuit 38 by a lead wire. The other input / output terminal of the matching circuit 38 is electrically connected to a transmitting / receiving circuit via a lead wire.

In such a configuration, the rod antenna 24
In a state in which the rod antenna 24 is pulled out, the stopper 32 at the base end of the rod antenna 24 is fitted and electrically connected to the holding fixture 22, and further electrically connected to the transmission / reception circuit via the power supply spring 36 and the matching circuit 38. The base end of the coil antenna 16 is electrically connected to a transmission / reception circuit via the power supply fitting 18, the mounting nut 12, and the power supply lug 34. Therefore, as shown in FIG. 4A, the rod antenna 24 and the coil antenna 16 are connected in parallel, and each has an antenna function. In addition, since the matching circuit 38 is interposed in the rod antenna 24, by appropriately setting the matching circuit 38, the input / output impedance of the coil antenna 16 and the matching circuit 38 in which the rod antenna 24 is in the pulled-out state. Matching with input / output impedance can be achieved, and signals received by the coil antenna 16 and the rod antenna 24 can be efficiently transmitted to the transmission / reception circuit. Also, signals can be transmitted efficiently in the opposite direction.

When the rod antenna 24 is stored, a stopper 32 at the base end of the rod antenna 24 is provided.
However, the rod antenna 24 is separated from the holding bracket 22, and is insulated from the power feeding spring 36. At this time, rod antenna 2
4 is, of course, insulated from the power supply lug 34 as well. Therefore, as shown in FIG. 4B, the rod antenna 24 does not act as an antenna, and the coil antenna 1
Only 6 acts as an antenna.

As described above, in the radio antenna according to the present invention, when the rod antenna 24 is pulled out, the coil antenna 16 and the rod antenna 24 operate as separate antennas, respectively, as in a conventional antenna of this type. The antenna does not function as a single antenna in a two-tiered configuration, and the adjustment of each individual antenna is easier.

In addition, when the rod antenna 24 is pulled out, the base end of the rod antenna 24 is connected to the power feeding spring 36 via the stopper 32.
And the electrical connection is stable without any intervening coupling capacitance. Since matching is achieved by the matching circuit 38, even if two antennas are connected in parallel to the transmission / reception circuit, signals can be efficiently transmitted, and the gain of the entire antenna can be improved.

If the coil antenna 16 and the rod antenna 24 are damaged, the housing 10 is opened by loosening the male screw at the lower end of the bobbin 14 from the female screw of the mounting nut 12 and removing it. The antenna can be easily replaced without any trouble. In a state where the bobbin 14 of the new antenna is screwed and mounted, the power supply fitting 18 abuts on the mounting nut 12 to be electrically connected.
It goes without saying that the power supply spring 36 is elastically connected to and electrically connected to the holding bracket 22.

In the above embodiment, the coil antenna 16 has a quarter wavelength and the rod antenna 24 has a 1/4 wavelength.
Although two wavelengths are used, the present invention is not limited to these, and can be applied to coil antennas and rod antennas having different input / output impedances.

[0019]

As is apparent from the above description, in the radio antenna of the present invention, when the rod antenna is stored, only the coil antenna acts as an antenna, and the rod antenna is pulled out. When
The coil antenna and the rod antenna function as separate antennas, are matched by a matching circuit, and the two antennas are connected in parallel to the transmission / reception circuit, so that a high antenna gain can be obtained as a whole antenna. Since the coil antenna and the rod antenna do not function as a single antenna by being stacked in two stages or the like, it is only necessary to adjust each antenna independently, and the adjustment is easy. In addition, the base end of the pulled-out rod antenna is reliably connected electrically without any intervening coupling capacitance or the like, and stable characteristics can be obtained.

If the bobbin around which the coil antenna is wound is made detachable by screwing into a mounting nut provided on the housing, the antenna can be replaced very easily without opening the housing. Maintenance is easy. Also,
An antenna having a coil antenna and a rod antenna having different effective lengths can be appropriately replaced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a radio antenna according to the present invention, in which (a) shows a state where a rod antenna is pulled out, and (b) shows a main part in a state where the rod antenna is housed. .

FIG. 2 is an external side view of the radio antenna shown in FIG.

3A and 3B show the holding bracket of FIG. 1, wherein FIG. 3A is a side view, and FIG. 3B is a sectional view taken along the line AA of FIG.

FIG. 4 is an equivalent circuit diagram of the wireless device antenna shown in FIG. 1, where (a) shows a state where a rod antenna is pulled out;
(B) shows a state where the rod antenna is housed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 housing 12 mounting nut 14 bobbin 16 coil antenna 18 power supply fitting 22 holding fixture 24 rod antenna 26 tube 32 stopper 34 power supply lug 36 power supply spring 38 matching circuit

Claims (2)

(57) [Claims] 1. A coil antenna is fixedly disposed so as to protrude outward from a housing of a wireless device, and a rod antenna is disposed so as to be able to be housed and pulled out of the housing of the wireless device by penetrating the coil antenna in an axial direction. And a base end of the coil antenna is electrically connected to a transmission / reception circuit of a wireless device, and a base end of the rod antenna in an extended state is electrically connected to the transmission / reception circuit via a matching circuit. The matching circuit is set so that the input / output impedance of the matching circuit and the input / output impedance of the coil antenna match in a state, and the rod antenna is not electrically connected to the coil antenna in the housed state of the rod antenna. Only the coil antenna and the rod antenna are electrically connected to the transmitting / receiving circuit so that the rod antenna is pulled out. An antenna for a wireless device, wherein the antenna is adapted to be electrically connected to the transmitting / receiving circuit in parallel with matching. 2. The wireless device antenna according to claim 1, wherein a mounting nut made of a conductive material having a female screw engraved therein for communicating the inside and outside of the housing is provided on the housing, and the coil antenna is wound. A bobbin made of an insulating material is detachably attached to the mounting nut at a lower end thereof by screwing, and the base end of the coil antenna is electrically connected to the mounting nut when the bobbin is mounted. Is electrically connected to the transmission / reception circuit, and the rod antenna is penetrated through a through hole provided in the bobbin in the axial direction so that the rod antenna can be stored and pulled out, and provided in the base at the base end of the rod antenna in the drawn state. The power supply spring made of a conductive material is electrically connected, and the power supply spring is electrically connected to the transmission / reception circuit via the matching circuit. Machine antenna.