JP2001223518A - Linear antenna for television - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a very small linear antenna for television which is obtained by making the antenna of a portable TV such as a small TV and a handy type TV very small and where the length of the antenna does not have to be adjusted. SOLUTION: One end part of a 2nd antenna element is connected to a 1st antenna element 11 capable of resonating in a UHF band through a 1st choke coil 21. The element 12 is formed so as to be able to resonate in a high band of a VHF band together with the element 11, and one end part of a 3rd antenna element 13 is further connected to the other end of the element 12 through a choke coil 22. The element 13 is formed so as to be able to resonate in a lower band of the VHF band together with the 1st and 2nd antenna element 11 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable television receiving antenna such as a small television or a handy television. More particularly, the present invention relates to a very short and compact television linear antenna which can perform stable reception only by adjusting the direction and does not need to adjust the length.

[0002]

2. Description of the Related Art Conventionally, as a receiving antenna of a small portable television (hereinafter, referred to as a TV), a rod antenna which can be expanded and contracted by sliding the inside in a metal pipe shape is used. By expanding and contracting the length of the rod antenna, it is possible to receive an antenna having a length corresponding to a channel (frequency) to be received. That is, the antenna can resonate and receive with high sensitivity as long as the antenna has a length of も wavelength (usually used at １ ／ wavelength) of the radio wave to be normally received. Therefore, by adjusting the length of the antenna to the optimum length according to the frequency to be received, it is possible to receive optimally on any channel, and it is formed so that it can be shortened when carrying. I have.

In a case where transmission and reception are performed in, for example, two frequency bands by a communication device or the like, as shown in FIG. 2, for example, a first antenna element 51 for a high frequency is used.
There is known an antenna having a structure in which a first antenna element and a second antenna element 52 having a quarter wavelength with respect to a low frequency are connected via a trap 53 together with the first antenna element. That is, the trap 53 is constituted by an LC circuit that performs parallel resonance with respect to a high frequency to be transmitted and received, so that the second antenna element 52 does not function at a high frequency, and only the first antenna element 51 is used. Since the impedance of the trap circuit 53 decreases at a low frequency, the first
And 1 in both the second antenna elements 51 and 52.
By using an antenna having a length of / 4 wavelength, two frequency bands can be transmitted and received.

[0004]

In the rod antenna as described above, the antenna cannot be formed in a coil shape.
A physical length almost equal to the electrical length of 波長 wavelength is required, and a length of about 50 to 100 cm is required, which is very inconvenient to carry and use. Furthermore, if you try to adjust the length and direction of the antenna suitable for the channel to watch TV, you must directly touch the metal pipe, so the impedance is different between when you touch the antenna and when you release your hand. In other words, even if the adjustment is optimally performed with the hand touched, there is also a problem that the adjustment is deviated from the optimal state when the hand is released and cannot be adjusted accurately.

Further, even if an attempt is made to use a method of separating each frequency band using a trap circuit as used in the above-mentioned communication equipment, in a TV, for example, the range of UHF is 47
Since it is as wide as 0 to 770 MHz, parallel resonance cannot be performed in such a wide range, and the antenna cannot be separated by the trap circuit. Further, in a configuration using such a resonance circuit, a structure in which a frequency band of three or more frequency bands is automatically switched and received cannot be provided.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and makes a portable TV antenna such as a small TV or a handy type TV very short and adjusts its length. Very small TV that does not need to be
It is an object of the present invention to provide a linear antenna.

[0007]

A linear antenna for TV according to the present invention has a first antenna element capable of resonating in the UHF band, and one end connected to the first antenna element via a first choke coil. A second antenna that is connected and can resonate with the first antenna element in a high band of the VHF band.
And an end connected to the other end of the second antenna element via a second choke coil, and capable of resonating in the low band of the VHF band with the first and second antenna elements. 3 antenna elements.

Here, the UHF band refers to a 470 to 770 MHz band corresponding to TV channels 13 to 62, which is a VHF band.
A high frequency band means a 170 to 220 MHz band corresponding to 4 to 12 channels, and a low VHF band means a 90 to 108 MHz band corresponding to 1 to 3 channels.

With this structure, the first choke coil increases the impedance with respect to the UHF band, operates only the first antenna element separately, and the second choke coil forms the VHF band. For frequencies equal to or higher than the high frequency, the impedance can be increased and the third antenna element can be separated, so that only an antenna element having a length corresponding to each frequency band functions as an antenna. In addition, the choke coil increases the impedance in a frequency band higher than a certain frequency, and does not form a resonance circuit at a specific frequency. Function. Furthermore, since the length does not need to be adjusted depending on the frequency band to be received, the outer periphery can be covered with an insulator, and the adjustment of the direction does not need to directly touch the conductor, and is performed in a very stable state. be able to.

[0010] By forming at least one of the first, second and third antenna elements in a coil shape, the physical length of the entire length can be shortened. Even when used for a portable TV, such as a small TV or a handy type TV, an antenna as short as about 10 cm can be used.

More specifically, the first and second choke coils are formed by tightly winding an end of the antenna element around a ferrite core, and the first choke coil is formed of a U-shaped choke coil.
The second choke coil has a high impedance with respect to the HF band and a low impedance with respect to the VHF band, and the second choke coil has a high impedance with respect to the high band of the VHF band and a low impedance with respect to the low band of the VHF band. Are formed to have low impedance. Since the ferrite core is used and is closely wound, the impedance can be increased with a short length, so that a desired impedance can be formed with a slight length.

[0012]

Next, a TV linear antenna according to the present invention will be described with reference to the drawings. A linear antenna for a TV according to the present invention includes a first choke coil 21 mounted on a first antenna element 11 that can resonate in the UHF band, as schematically shown in FIG. One end of the second antenna element 12 is connected via the second antenna element 12. This second antenna element 1
2 is formed so as to resonate with the first antenna element 11 in a high VHF band. This second
The other end of the antenna element 12 is further connected to one end of a third antenna element 13 via a second choke coil 22. The third antenna element 13 is formed so as to resonate with the first and second antenna elements 11 and 12 in a low band of the VHF band.

The first, second, and third antenna elements 11, 12, and 13, and the first and second choke coils are each made of a single wire such as a copper wire having a thickness of about 0.6 mmφ. It is formed in a continuous coil shape. The first and second choke coils 21 and 22 are tightly wound around ferrite cores 21a and 22a as described later, and the first to third antenna elements 11 to 13 are provided.
Are formed in a coil shape at such a pitch that no interaction occurs between adjacent elements.

The first antenna element 11 is a UHF
It is formed by winding the length corresponding to the electrical length that resonates at λ / 4 in the frequency band of the band (13 to 62 channels) in a coil shape. Also, the second antenna element 12
Is a high frequency band of the VHF band (4-1 to 1) together with the first antenna element 11 and the first choke coil 21.
(2 channels) so as to have an electrical length that resonates at λ / 4. Further, the third antenna element 1
3 denotes first and second antenna elements 11 and 12
And the first and second choke coils 21 and 22 together with λ in the low frequency band (1 to 3 channels) of the VHF band.
It is formed to have an electrical length that resonates at / 4.

The reason why the antenna element portion is formed in a coil shape is to shorten the entire physical length while maintaining the electrical length at a predetermined length. The coil is wound at such a pitch as to have no influence, and such a coil shape is preferable because the entire antenna can be reduced in size. For example, the diameter of the coil is about 8 mmφ, and the lengths of the first to third antenna elements 11, 12, and 13 are each 30.
mm, 25 mm, and 40 mm.

The first choke coil 21 is formed by winding one end of the antenna element 11 around a ferrite core 21a having a diameter of, for example, 6 mm and a length of about 10 mm. The first choke coil 21 acts as a high impedance in the UHF frequency band, and acts to divide the second and third antenna elements 12 and 13 on the distal end side. , By winding around the ferrite core 21a, and by tightly winding the coil,
A larger inductance is obtained, and a short choke coil provides a blocking effect. The aforementioned diameter is 6mmφ,
A first choke coil 21 having the above-described function is formed by winding a coil of about 6 turns around a ferrite core 21a having a length of about 10 mm.

Similarly, the second choke coil 22 has a VH
It acts as a high impedance for the high frequency band of the F band, and has a low impedance that is hardly affected by the low frequency band of the VHF band. Core 22a
Then, by winding a coil of about 8 turns, the choke coil 22 having the above-described function is formed. As a result, for the high frequency band of the VHF band, the third antenna element 13 operates without the third
For low frequency bands, the influence of the first and second choke coils 21 and 22 is small, and the first and third antenna elements 11 to 13 act as if there is no choke coil. Resonates as an electrical length of / 4.

A cover 3 is provided on the outer periphery of each of the antenna elements 11 to 13 and the choke coils 21 to 22 by, for example, coating with vinyl chloride or the like. , Connector 4 are connected to each other so that a coaxial cable can be connected. As a result, a very small antenna having a total length L of about 11.5 cm and a diameter D of about 8 mm shown in FIG. 1 is obtained.

According to the linear antenna for TV of the present invention, U
The antenna element of the optimum length automatically functions as an antenna according to the high frequency band and the low frequency band of the HF band and the VHF band. Therefore, without adjusting the antenna length according to the frequency band to be received. Can be received.
In addition, since it is not necessary to extend and contract the antenna, the antenna can be formed in a coil shape, and the physical length can be extremely reduced while maintaining the electrical length at a predetermined length. Therefore, it is a very short TV antenna suitable for small and handy type TVs and capable of receiving all frequency bands. In addition, since it is not necessary to adjust the length unlike a conventional rod antenna, the periphery can be covered with an insulator and fixed, and even when adjusting the direction of the antenna, it can be directly applied to the conductor of the antenna. There is no need to touch and it can be used in a very stable state.

[0020]

According to the present invention, the entire frequency band for TV can be received by one antenna, and it is not necessary to adjust the length of each one at the time of reception. Also, since there is no need to expand and contract the antenna, the antenna wire can be wound in a coil shape, and its physical length can be very short, for example, about 10 cm. Therefore, a compact TV or a handy type TV can be made compact and easy to use.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of a TV linear antenna according to the present invention.

FIG. 2 is an explanatory diagram of a linear antenna used in two frequency bands by coupling a conventional trap circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 1st antenna element 12 2nd antenna element 13 3rd antenna element 21 1st choke coil 22 2nd choke coil

Claims (3)

[Claims] 1. A first antenna element capable of resonating in a UHF band, and one end connected to the first antenna element via a first choke coil, and a high VHF band together with the first antenna element. A second antenna element capable of resonating in a band, and one end connected to the other end of the second antenna element via a second choke coil, and a VHF band together with the first and second antenna elements. And a third antenna element capable of resonating in a low band. 2. The linear antenna according to claim 1, wherein at least one of the first, second, and third antenna elements is formed in a coil shape. 3. The first and second choke coils are such that an end of the antenna element is densely wound around a ferrite core, the first choke coil has a high impedance with respect to a UHF band, and has a VHF band. Band, the second choke coil has a V
3. The linear antenna according to claim 1, wherein the linear antenna is formed to have a high impedance in a high band of the HF band and a low impedance in a low band of the VHF band.