JPS6211041Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a UHF-VHF common antenna device, and particularly to an antenna device that is well-organized, has a simple structure, and can provide sufficient performance as a common antenna.

Conventionally, as shown in FIG. 1, this type of UHF-VHF antenna device is located on the back of a television receiver 1, as shown by reference numeral 2, and the direction can be changed.
Most antennas are fixed so that their height cannot be changed, but this type of antenna is unsuitable for indoor antennas, where the electric field strength varies greatly depending on the location.

As an improvement on this point, as shown in Fig. 2, a bow tie antenna 4 for UHF is removably attached to a suitable position of a telescopic pole antenna 3 for VHF whose base end is supported in a tiltable manner. ,
When receiving UHF broadcasts, there are some models that use a telescopic pole antenna 3 for VHF as a support pillar so that the height can be changed, but this type is simply a combination of mutually independent antennas. Therefore, when receiving VHF broadcasts, UHF antenna 4 and feeder 5, and when receiving UHF broadcasts, VHF antenna 3 not only deteriorate the reception performance of each antenna, but also
Problems such as the UHF feeder 5 getting in the way occur.

As an improvement on this point, as shown in FIG. There are antennas that are arranged in parallel and operated as a loop antenna when receiving UHF broadcasts and as a monopole antenna when receiving VHF broadcasts by changing the UHF-VHF changeover switch 9.
In this type, it is necessary to operate the changeover switch 9 when switching between UHF and VHF, and since the antenna is connected via the feeder 11 to rotate via the tilting fitting 10, the rotation is not possible. The angle etc. are limited, and the loop antenna 6
Since a pair of telescopic tubes 7a and 7b are arranged below the
As a whole, the support part of the device has been increased in size, and this type of antenna has not been adopted because it is not suitable as an antenna attached to a television or the like.

The present invention aims to provide a UHF-VHF common antenna device that does not have the above-mentioned drawbacks of the conventional products, is well-organized as a whole, has a simple structure, and has sufficient performance as a common antenna.

An embodiment of the present invention will be described below with reference to FIG.

In the figure, 13 is a UHF antenna with an appropriate mass. Although the antenna 13 is shown as a loop antenna in the illustrated example, it may be a bow-tie antenna or other balanced UHF antenna. Both terminals of the UHF antenna 13 are supported by a fixing member 14 made of an insulating material such as synthetic resin. The upper ends of the uppermost inner and outer metal poles 15a and 15b are fixed to the fixing member 14, and the upper end of the inner pole 15a is fixed to the UHF antenna 1.
The upper end of the outer pole 15b is connected to one terminal of 3.
They are each electrically connected to the other terminal of the UHF antenna 13. Inner and outer poles 15
a and 15b are integrally held together via a spacer 16 made of an insulating material.

A conductive metal member 17 is provided on the outer periphery of the outer pole 15b.
is attached, and this conductive metal member supports the lower end of a conductor 18 which extends upwardly substantially parallel to the poles 15a, 15b. The upper end of the conductor 18 is attached to the fixing member 14. Conductive metal member 1
7, the conductor 18, etc. constitute a mode conversion device for matching between the loop antenna 13 as a balanced antenna and the coaxial conductive tube as an unbalanced antenna which will be described below.

The upper end of a first-stage inner conductive tube 19a is fixed to the lower end of the inner pole 15a, and a second-stage inner conductive tube 20a is fixed to the outside of the first-stage inner conductive tube 19a.
is slidably fitted. In the illustrated state, the first-stage inner conductive tube 19a is at the most upwardly slid position with respect to the second-stage inner conductive tube 20a,
A well-known elastic member 22 attached to the lower end of the conductive tube 19a forms an inward bend 23 at the upper end of the conductive tube 20a.
By colliding with the conductive tube 19a, the conductive tube 19a is prevented from coming off against the conductive tube 20a. 2
The third inner conductive tube 21a is slidably fitted on the outside of the inner conductive tube 20a in the same way as described above. In the illustrated state, the conductive tube 20a is at the most upwardly slid position with respect to the conductive tube 21a.

The upper end of a first-stage outer conductive tube 19b is fixed to the lower end of the outer pole 15b, and a second-stage inner conductive tube 20 is attached to the outside of the first-stage inner conductive tube 19b.
b is slidably fitted. The position where the first and second stage outer conductive tubes 19b, 20b relatively extend the most is determined by the collision between the elastic member 24 and the bent portion 25, as in the case of the inner conductive tube. A third outer conductive tube 21b is slidably fitted outside the second outer conductive tube 20b. As in the case of the inner conductive tubes 19a, 20a, and 21a, the outer conductive tubes 19b, 20b, and 21b are also fully extended upward in the illustrated state.

An insulating spacer 27 is interposed between the inner and outer conductive tubes, for example, the third stage conductive tubes 21a and 21b, to hold them together at a constant distance. First stage inner and outer conductive tubes 19a, 19b, 2
The inner and outer conductive tubes 20a and 20b of the tiers and the inner and outer conductive tubes 21a and 21b of the third tier all have a constant diameter ratio (ratio of the outer diameter of the inner conductive tube to the inner diameter of the outer conductive tube). are doing. All of the inner and outer conductive tubes constitute a telescopic coaxial conductive tube whose diameter becomes smaller as it goes upward. In the illustrated embodiment, the number of stages is shown as three for convenience, but the number of stages can be determined arbitrarily, and in some cases, the inner and outer poles 15a and 15b of the uppermost stage can also be expanded and contracted in the same way as the conductive tube. It may be configured freely.

The bottom of the third stage outer conductive tube 21b of the coaxial conductive tubes described above is supported on a support base 29 by a known tiltable metal fitting 28 so as to be tiltable.

The terminal fittings 30 provided on the lower side of the support stand 29 are
Rotatable metal fitting 28 with respect to the stage outer conductive tube 21b
is electrically connected to this via a capacitor C.
1, C2 and an inductance coil L are connected to a terminal on the capacitor C1 side of a branching circuit 32. The terminal on the capacitor C2 side of this branching circuit 32 is connected to the VHF feeder line 33,
A terminal between the capacitors C1 and C2 is connected to the outer conductor 34b of the UHF power supply line 34. Further, the lower end of the third-stage inner conductive tube 21a is connected to the core wire 34a of the UHF power supply line 34 via a conductor 35.

Next, the operation of the antenna device described above will be explained.

For use as a UHF antenna, the UHF
The high frequency voltage induced by the radio waves received by the antenna 13 is converted from balanced to unbalanced by the balloon constituted by the mode conversion devices 17 and 18, and the high frequency voltage is converted from balanced to unbalanced by the balloon constituted by the mode conversion devices 17 and 18, and the high frequency voltage is converted from balanced to unbalanced by the balloon constituted by the mode conversion devices 17 and 18.
The signal is transmitted to the lower end of the coaxial conductive tube, with the outer conductor being the outer conductor and the inner conductive tubes 19a, 20a, and 21a being the inner conductors. Then, the inner conductor passes through the conductor 35.
It is connected to the core wire 34a of the UHF feeder line 34, and the outer conductor is connected to the UHF feeder line 34 through the branching circuit 32.
The high frequency voltage is transmitted to the receiver via the feed line 34. On the other hand, due to the action of the inductance coil L of the branching circuit 32, the UHF voltage with a higher frequency than VHF is
It is prevented from being transmitted to the VHF feeder line 33. The conductor 18 of the mode conversion device is parallel to the poles 15a and 15b as described above, and therefore, when attaching the conductive metal member 17 to the outer pole 15b, the member 17 is slid in the longitudinal direction of the outer pole. Even if the conductor 18 is moved and finely adjusted, the conductor 18 fixed to the fixed member 14 is not mechanically affected. That is, the only difference is whether the conductor 18 is inserted deeply or shallowly into the hole of the conductive metal member 17. Therefore, the position of the conductive metal member 17 can be slightly adjusted while being attached to the outer pole 15b. By connecting the conductor 18 to the conductor 18, optimum matching of the mode conversion device can be achieved.

When used as a VHF antenna, the outer conductive tubes 19b, 20b, 21b, including the antenna 13, operate as a monopole antenna, and the branching circuit 32 acts as a passband in the frequency band below VHF. to the VHF feeder line 33.
VHF voltage is transmitted.

The antenna device of the present invention having the above-described configuration and function can freely change the height and direction by being equipped with a telescoping coaxial conductive tube and a tiltable metal fitting. By using a simple configuration in which the UHF antenna is supported at the tip of the conductive tube via a mode converter, the drawbacks of the conventional products mentioned above can be eliminated, and a strong connection between the balanced antenna and the unbalanced antenna can be obtained. Moreover, it has a form that is suitable for attaching it to a television or the like.

In addition, the coaxial conductive tube part acts as a coaxial feed line in the UHF band, and its outer conductor also acts as a VHF antenna in the VHF band, so it functions well as a shared antenna, especially in each stage. Since the diameter ratio of the inner conductive tube and the outer conductive tube that face each other is fixed, the coaxial multistage conductive tube acts as a coaxial transmission circuit, and the antenna performance does not deteriorate due to expansion and contraction, and the transmission The characteristic impedance of the circuit does not change. On the other hand, in the conventional example shown in Fig. 3, the characteristic impedance between the rod elements of each stage is different, so when the antenna is expanded or contracted to adjust the height, the transmission of each characteristic impedance is If the circuit length is set to an arbitrary length and the impedance matching is made the best during full extension, there will be a drawback that the impedance matching will deviate from the best point during intermediate extension. Such a drawback does not occur in the present invention, and since the diameter ratio of each stage of the multi-stage conductive tube is constant, the characteristic impedance is constant in each stage, and impedance matching can always be achieved at the best possible level even through expansion and contraction. It can be kept in this condition.

In addition to the above-mentioned effects, in the present invention, since the coaxial transmission line is constituted by the coaxial conductive tube, the antenna has the advantage of being less susceptible to external influences and less likely to pick up noise. Even if you touch the external conductive tube for expansion/contraction operations, there is almost no effect.

In addition, in this invention, since a branching circuit is interposed at the base end of the antenna device, there is no need for the trouble of switching with a conventional switch, and only the necessary radio waves can be automatically received. The advantage is that the device is easy to handle.

Furthermore, in the present invention, coaxial multi-stage conductive tubes are used as a balanced antenna and an unbalanced antenna, and a mode converter and a branch circuit are provided in a specific manner, thereby achieving a well-organized structure as a whole. is simple and has sufficient performance
You can get an antenna for both UHF and VHF. In the mode conversion device used in the present invention, the conductor whose tip is fixed to an insulating fixing member interposed between the tip of the coaxial conductive tube and the balanced UHF antenna is approximately parallel to the coaxial conductive tube. Therefore, even if the conductive metal member connected to the base end of the conductor is slightly displaced in the longitudinal direction of the conductor (the longitudinal direction of the coaxial conductive tube), the conductor will not be mechanically affected.
Therefore, the matching of the mode converter can be finely adjusted by slightly displacing the conductive metal member when it is attached to the coaxial conductive tube. This mode conversion device itself has a simple structure and is easy to manufacture.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are views showing examples of conventional antenna devices, respectively, and FIG. 4 is a front view partially showing a longitudinal section of the antenna device of the present invention. 13... UHF antenna, 14... Insulator fixing member, 15a, 15b... Inner and outer poles, 17, 1
8...Mode conversion device (17...Conductive metal member,
18... Conductor), 19a, 20a, 21a... Inner conductive tube, 19b, 20b, 21b... Outer conductive tube, 27... Insulating spacer, 28... Rotatable metal fitting, 29... Support stand, 32 ...branching circuit, 33
...VHF feeder line, 34...UHF feeder line, 3
4a... Core wire, 34b... Outer conductor, 35... Conductor.

Claims (1)

[Scope of utility model registration request] Inner conductive tubes 19a to 21a and outer conductive tube 1
A coaxial multi-stage conductive tube as an expandable and retractable unbalanced antenna consisting of 9b to 21b and having a constant inner and outer diameter ratio of all stages, and one end and the other end at the tips of the inner and outer conductive tubes of this coaxial multi-stage conductive tube, respectively. Balanced UHF antenna 13 provided at the tip of the coaxial conductive tube so as to be electrically connected, and fixation of an insulator interposed between the tip of the coaxial conductive tube and the balanced UHF antenna to integrally fix the two. member 14, a conductive metal member 17 supported on the outside of the outer conductive tube 15b at the tip of the coaxial conductive tube closer to the proximal end than the fixed member, and a conductive metal member 17 whose proximal end is connected to this conductive metal member and is substantially parallel to the coaxial conductive tube. and the tip thereof is connected to the fixing member 1.
4, a metal fitting 28 that rotatably supports the base end of the coaxial conductive tube, and a mode converter configured by the conductor 18 fixed to the coaxial multistage conductive tube, and a metal fitting 28 that rotatably supports the base end of the coaxial conductive tube, and The UHF-
VHF common antenna device.