JP2003008328A - Phase difference feed antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the FB ratio and realize the miniaturization. SOLUTION: Two linear radiators 4a, 4b are disposed in parallel with a specified spacing from each other. Two coaxial cables 10a, 1b of selected different lengths connect the radiators 4a, 4b to a two-way distributor 12 so that reception outputs of the radiators 4a, 4b are inputted in phase to the two-way distributor 12. The spacing between the radiators 4a, 4b is selected to be shorter than the wavelength λ (center wavelength of the two radiators)/8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase difference feeding antenna used for receiving television broadcasting of UHF band and VHF band, for example.

[0002]

2. Description of the Related Art A Yagi antenna is sometimes used as an antenna for receiving television broadcasts in the UHF band and the VHF band. In this Yagi-shaped antenna, in order to improve the FB ratio, a reflector, a radiator, and a director and three or more elements are used, or the radiator is V-shaped.

[0003]

However, when the number of elements is increased, the size of the entire antenna becomes large. Also,
When the radiator has a V-shape, the antenna length required for reception is shortened, and therefore the length of the antenna element must be increased, and the entire antenna is also large.

An object of the present invention is to provide an antenna having a small FB ratio and a small size.

[0005]

In a phase difference feeding antenna according to one aspect of the present invention, two linear radiators are arranged in parallel with each other with a predetermined interval. The two transmission paths are selected to have different lengths so that the reception outputs based on the radio waves coming from the predetermined directions of the two radiators input to the combiner have the same length, and the two radiators are selected. And the synthesizer are connected. The distance between the two radiators is selected to be shorter than λ (center wavelength of the two radiators) / 8.

Since the phase difference feeding antenna is used in this way, a good FB ratio can be obtained for radio waves from a predetermined direction, and the distance between the two radiators is the same as that of the normal phase difference feeding. Λ / 4 to λ / 8 normally selected for antenna
Since it is selected shorter than the above, the entire antenna can be downsized.

This phase difference feeding antenna is an antenna for receiving television broadcasts in the low VHF band and the high VHF band, and the distance between the two radiators can be about 100 mm.

For example, when the phase difference feed antenna is for the low VHF band, the distance between the radiators is usually about 500 mm, and when it is for the high VHF band, the distance between the radiators is usually about 190 mm. However, the distance between the radiators of the phase difference feeding antenna of this embodiment is further shortened to about 100 mm, and the entire antenna can be downsized, and the VH is further reduced.
It is a wideband antenna that can be used in both the F band and the high VHF band.

The two radiators may be constituted by rod antennas. With this configuration,
When not receiving, since the two radiators can be shortened, the entire antenna can be further downsized.

In the phase difference feeding antenna according to another aspect of the present invention, the first and second radiators are arranged in parallel. First and second transmission lines connect the first and second radiators to the first combiner. The lengths of the first and second transmission lines are selected so that the radio waves coming from the first radiator side are combined in phase with each other in the first combiner. The third and fourth transmission lines connect the first and second radiators to the second combiner. The lengths of the third and fourth transmission lines are selected so that the radio waves coming from the second radiator side are combined in phase with each other in the second combiner. A state in which the first and second transmission lines are connected to the first combiner, the third and fourth transmission lines are separated from the second combiner, and the first and second transmission lines are separated from the first combiner. The switching means switches to one of the state in which the third and fourth transmission lines are separated and connected to the second combiner.

In the phase difference feeding antenna of this aspect, by switching the switching means, it is possible to improve the FB ratio with respect to the radio wave coming from the direction of the first radiator, and the second radiator. F for radio waves coming from any direction
It is also possible to improve the B ratio.

A phase difference feeding antenna according to another aspect of the present invention has two linear radiators having different center frequencies. The two transmission paths are selected to have different lengths so that the reception outputs based on the radio waves coming from the predetermined directions of the two radiators input to the combiner have the same length, and the two radiators are selected. And the synthesizer are connected.

According to this structure, since the center frequencies of the two radiators are different from each other, it is possible to provide an antenna having a wide band and a good FB ratio for radio waves coming from a predetermined direction. .

The tips of the two radiators can be bent respectively. With this configuration, the widthwise dimension of the radiator can be shortened, and the entire antenna can be downsized.

Furthermore, the folding of the two radiators can be carried out in opposite directions. With this configuration, it is possible to obtain a good FB ratio without interfering with each other, and it is also possible to narrow the distance between the two radiators, and to downsize the entire antenna.

A phase difference feeding antenna according to still another aspect of the present invention includes a VHF band receiving antenna and a UHF band receiving antenna. The VHF band receiving antennas include first and second VHF band receiving antennas arranged in parallel with each other at a predetermined interval.
Of the linear radiator, the first combiner, and the first and second radiators input to the first combiner have in-phase reception outputs based on radio waves in the VHF band coming from predetermined directions. So that the two radiators are selected to have different lengths, and the first radiator and the second transmission line connecting the two radiators and the combiner are provided, and the distance between the two radiators is , Λ (center wavelength of the two radiators) / 8 is selected.
The UHF band receiving antennas are arranged in front of the first and second radiators and have third and fourth center frequencies different from each other.
Of the linear radiator, the second synthesizer, and the third and fourth radiators input to the second synthesizer, which are based on the UHF band radio wave coming from the predetermined direction, It is provided with third and fourth transmission lines that are selected to have different lengths so as to be in phase, and that connect the two radiators and the combiner. Both ends are bent in opposite directions.

In the phase difference feeding antenna configured as described above, the third and fourth UHF band third and fourth shorter lengths are provided in front of the first and second radiators for the VHF band.
Radiators are arranged in parallel and the first for the VHF band
The distance between the second radiator and the second radiator is selected to be narrow, and the third and fourth radiators for the UHF band are also bent at opposite ends in opposite directions to shorten the distance, so that a small VHF band and a UHF band are formed. Can be used as an antenna.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A UHF band and VHF band receiving antenna according to an embodiment of the present invention has a housing 2 as shown in FIG. The plane shape of the housing 2 is selected such that the width dimension on the arrival direction A side (tip side) of radio waves in a plurality of different frequency bands, for example, radio waves for television broadcasting in the UHF band and the VHF band is the shortest. The first trapezoidal portion 2a whose width dimension gradually increases as it progresses along the traveling direction.
And a width dimension gradually decreases from the bottom side of the first trapezoidal portion 2a toward the traveling direction of the radio wave.
And a trapezoidal portion 2b. The length dimension of the first trapezoidal portion 2a is selected to be longer than the length dimension of the second trapezoidal portion 2b.

The phase difference feeding antenna 4 for receiving the VHF band is housed in the second trapezoidal portion 2b. On the other hand, the modified Yagi antenna 6 for receiving the UHF band is housed in the first trapezoidal portion 2a.

Phase difference feeding antenna 4 for VHF band reception
Has two radiators 4a and 4b, as shown in FIG. These two radiators 4a and 4b are, for example, center-feed type linear elements configured by rod antennas whose lengths can be expanded and contracted. The radiators 4a and 4b are arranged perpendicular to the arrival direction A of the radio wave, and the radiators 4a and 4b are arranged parallel to each other. These radiators 4a and 4b have a reception center frequency λ.
Is about 160 MHz, the distance L1 from the feeding point to the tip is selected to be about 715 mm. Balloons 8a and 8b are connected to the feeding points of these radiators 4a and 4b, and these balloons 8a and 8b are combined via a transmission line, for example, coaxial cables 10a and 10b, specifically, a phase combiner, As an example, the two distributors 12 are connected.

The lengths of the coaxial cables 10a and 10b are different. For example a balloon of radiator 4a and two distributors 1
The length of the coaxial cable 10a connecting with 2 is about 80
Selected to mm. On the other hand, the balloon 8 of the radiator 4b
coaxial cable 10b connecting b and the distributor 2
Is selected to be about 220 mm. The difference in length is that the distance between the radiators 4a and 4b is λ.
Even if it is shorter than / 8, for example, 100 mm, the received signal from the arrival direction A transmitted from the two radiators 4a and 4b is in phase with the two distributor 12, and the received signal from the opposite direction to the arrival direction A is This is because the phase difference feeding antenna has an opposite phase.

In the phase difference feeding antenna for the low VHF band, the distance between the radiators may be about 500 mm,
In the phase difference feeding antenna for the high VHF band, the distance between the radiators may be about 190 mm. Compared with this, the distance between the radiators is 100 mm, which is very small in spite of being for the low and high VHF bands, and in this phase difference feeding antenna, the dimension in the arrival direction of radio waves is shortened. be able to.

Further, since the radiators 4a and 4b are constituted by rod antennas, the lengths of the radiators 4a and 4b can be shortened when the phase difference feeding antenna is not used, so that the casing can be reduced. It can be shortened to a state where it hardly projects from the hypotenuse portion of the second trapezoidal portion 2b of the body 2.
Further, since it is a phase difference feeding antenna, a good FB ratio can be obtained. FIG. 6A shows a high VHF band, for example, 198.5.
As is clear from this figure, a good FB ratio of about 13.2 dB can be obtained from the directional pattern of this antenna at MHz. The figure (b) is a low VHF band, for example, 112 MH.
As is clear from this figure in the directional pattern of this antenna at z, a good FB ratio of about 12.6 dB is obtained.

As shown in FIG. 1, the modified Yagi antenna for the UHF band has a reflector 14 in the vicinity of the phase difference feeding antenna 4a for the VHF band, and is located at a position closer to the tip side of the housing 2 than this. The radiator group 16 including the phase difference feeding antenna is provided, and the director 18 is provided at a position closer to the tip side of the housing 2 than the radiator group 16.

The reflector 14 is formed in an arcuate shape that is convex toward the tip of the housing 2 and has a total length of about 300 mm. The circular arc shape is for housing in the housing 2.

The center of the radiator 16a of the radiator group 16 is located about 40 mm from the most projecting position of the reflector 14 and at a position along the tip side of the housing 2. As shown in FIG. 3, the radiator 16a is a central power feeding type linear one, and both ends thereof are folded back to the reflector 14 side.
The linear portion of the radiator 16a is arranged substantially perpendicular to the arrival direction A of the radio wave.

The distance between the feeding points of the radiator 16a is about 2
The length of the linear portion from the feeding point to the bending point is set to about 110 mm, and the length of the bent portion is set to about 40 mm. In the radiator 16a, the lengths of the linear portion and the bent portion are selected so that the radiator 16a resonates at a reception center frequency of about 680 MHz. In the present embodiment, the bending angle of the bending portion is such that the bending portion forms an obtuse angle with respect to the linear portion so as to be substantially parallel to the hypotenuse of the first trapezoidal portion 2a of the housing 2 as shown in FIG. Has been. However, it can be bent to form an angle of up to 90 degrees with respect to the linear portion. Since the bent portion is provided as described above, the radiator 16 can be satisfactorily received at a desired reception center frequency and the radiator 16 is provided in the first trapezoidal portion 2a of the housing 2.
a can be accommodated.

The casing 2 is better than the linear portion of the radiator 16a.
For example, at a position about 90 mm on the tip side of the radiator 16
The straight line portion of b is arranged. The radiator 16b is also a straight line of the central feeding type, and the distance between the feeding points is about 15
The length is set to mm, and both ends are bent toward the tip end side of the housing 2 opposite to the reflector 14. This radiator 16b
The linear portion of is arranged in parallel with the linear portion of the radiator 16a. The length of the straight portion of the radiator 16b is about 80.
mm, and the length of the folded portion is selected to be about 20 mm. In the radiator 16b, the lengths of the linear portion and the bent portion are selected so that the radiator 16b resonates at a reception center frequency of about 800 MHz. The bent portion also functions as impedance adjustment. The bent portion is bent along the hypotenuse of the first trapezoidal portion of the housing 2. The bent portion can be bent until the angle with the linear portion becomes about 60 degrees. Since the bent portion is provided as described above, it is possible to satisfactorily receive at the desired reception center frequency, and it is possible to house the radiator 16b in the housing 2. Moreover, the radiators 16a and 16b do not interfere with each other because the bent portions of the radiators 16a and 16b have opposite bending directions.

Balloons 18a and 18b are connected to the feeding points of the radiators 16a and 16b, respectively. These balloons 18a and 18b are connected to a combiner, for example, a phase combiner, for example, a two-divider 22 via transmission lines having different lengths, for example, coaxial cables 20a and 20b. The coaxial cable 20a connecting the balloon 18a of the radiator 16a to the two distributor 22 has a length of about 75 m.
Selected as m. In addition, the balloon 1 of the radiator 16b
Coaxial cable 20b connecting 8b to 2 distributor 22
The coaxial cable 20b connecting the
Its length is selected to be 190 mm. The reason why the lengths of the coaxial cables 20a and 20b are selected in this way is that
A signal having a frequency intermediate between the reception center frequency of the radiator 16a of about 800 MHz and the reception center frequency of the radiator 16b of about 680 MHz, for example, a frequency of 740 MHz, which is propagated from the arrival direction A is generated by the radiators 16a and 16b. This is because when the distance is about 90 mm, the two phases are supplied to the two distributor 22 in the same phase and those propagated from the opposite direction to the arrival direction A are supplied to the two distributor 22 in the opposite phase.
This 90 mm interval is about 1/5 of the wavelength of the reception center frequency of 740 MHz, which is shorter than the 1/4 wavelength.

Since the receiving center frequencies of the two radiators 16a and 16b are different, the band of the radiator group 16 can be broadened. Moreover, the phase difference feed is applied to the radiator 16
Since a and 16b are performed, a good FB ratio can be obtained. Further, the distance between the radiators 16a and 16b is shorter than the quarter wavelength of the reception center frequency, and the tips of the radiators 16a and 16b are bent, so that the radiator is provided inside the housing 2. 16a and 16b can be accommodated compactly.

From the radiator 16b to the tip side of the housing 2, about 2
The director 18 is provided at a position 5 mm away. The director 18 has a length of about 120 mm. As described above, in the modified Yagi antenna using the reflector 14, the radiator group 16, and the director 18, since the radiator group 16 has a wide band and has a good FB ratio as described above,
This modified Yagi antenna also has a good FB ratio in a wide band. FIG. 7 is a directional characteristic diagram of this antenna in the UHF band, for example, 630 MHz. As is clear from this figure, a good FB ratio of about 17.4 dB is obtained. Further, in this embodiment, a modified Yagi antenna for the UHF band is present in front of the radiators 4a, 4b of the VHF band receiving antenna (in the direction close to the direction of arrival of radio waves), and the reflector 14 and VHF of the modified Yagi antenna are provided. The distance between the band and the radiator 4a is about 50.
Since the radiator 4a also functions as a radiator during reception in the UHF band, the FB ratio is further improved.

Although not shown in FIG. 1, in reality, the receiving antenna for the UHF band and the VHF band is provided with an amplifier and is configured as a so-called active antenna. Moreover, as shown in FIG. 4, the reception outputs of the radiators 4a and 4b for the VHF band are amplified by the amplifiers 24a and 24b, and then transmitted through the coaxial cables 10a and 10b.
It is supplied to the distributor 12 and synthesized. Similarly, U
The reception outputs of the radiators 16a and 16b for the HF band are also amplified by the amplifiers 26a and 26b, and then the coaxial cable 20
It is supplied to the two-way distributor 22 via a and 20b and is synthesized. This is because the S / N ratio can be improved as compared with the case where amplification is performed after combining by the two dividers 12 and 22.

In the above embodiment, the reception antenna in the VHF band is F for the radio wave from the arrival direction A.
The coaxial cable 10 is configured to improve the B ratio.
By selecting the lengths a and 10b, on the contrary, it is possible to improve the FB ratio for the radio waves coming from the direction opposite to the arrival direction A.

Further, by further developing this, for example, as shown in FIG. 5, in order to improve the FB ratio for the radio wave from the arrival direction A, the FB ratio for the radio wave from the B direction opposite to the arrival direction A is obtained. Can also be configured to be switched so that

That is, FB for the radio wave from the arrival direction A
Coaxial cable 10 whose length is selected to give a good ratio
In addition to a and 10b, the coaxial cable 110 whose length is selected so as to have a good FB ratio for radio waves from the direction B
a and 110b are prepared. 1 additional 2 divider 12
Instead, two two distributors 12a and 12b are prepared.
One end of the core wires of the coaxial cables 10a and 10b is connected to the two distributor 12a, and the other end of each core wire is connected to the switching means, for example, PIN diodes 120a and 120b, and the balloons 8a and 8b of the radiators 4a and 4b are connected. Connect to one end. The outer conductors of the coaxial cables 10a and 10b, the balloon 8a,
The other end of 8b is grounded by ground plates 122a and 122b. Similarly, the coaxial cable 110 is connected to the two distributor 12b.
a and 110b are connected to one ends of the core wires, and the other ends of the core wires are connected to switching means, for example, PIN diodes 120c, 1
Balloons 8a, 8b of radiators 4a, 4b via 20d
Connect to one end of. The outer conductors of the coaxial cables 110a and 110b are also grounded by the ground plates 122a and 122b.

Then, the radio wave from the arrival direction A is transmitted to a favorable F
When receiving at the B ratio, an appropriate direct current is supplied from the 2 divider 12a side, and the PIN diodes 120a and 120b are supplied.
To conduct. In addition, the radio wave from the arrival direction B can be transmitted to a good F
When receiving at the B ratio, an appropriate direct current is supplied from the 2 divider 12b side, and the PIN diodes 120c, 120d are supplied.
To conduct. That is, the PIN diodes 120a, 12
When the group of 0b is conducting, the PIN diode 1
To prevent the pair of 20c and 120d from conducting, on the contrary, PIN
When the pair of diodes 120a and 120b is not conducting, control is performed so that the pair of PIN diodes 120c and 120d is conducting.

In the above embodiment, the receiving antenna 4 for the VHF band and the receiving antenna 6 for the UHF band are provided in the housing 2 to serve as the receiving antennas for the VHF band and the UHF band. The receiving antenna 4 for the band and the receiving antenna 6 for the UHF band can be used individually. Further, the receiving antenna 4 for the VHF band is a low VHF
The band and the high VHF band are both used, but the radiators 4a and 4b are used.
Select the appropriate length for low VHF band or high VH
It can also be configured exclusively for the F band.

[0038]

As described above, according to the present invention, it is possible to obtain a small-sized phase difference feeding antenna having a good FB ratio. Further, it is possible to obtain a phase difference feeding antenna having a good FB ratio in a wide band, and it is also possible to provide a phase difference feeding antenna capable of switching the direction in which the FB ratio can be made good.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an antenna according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a VHF band reception antenna used in the antenna of FIG.

FIG. 3 is a schematic configuration diagram of a radiator used for a UHF band reception antenna used for the antenna of FIG.

FIG. 4 is a block diagram of the antenna of FIG.

5 is a schematic configuration diagram of a modified example of the VHF band reception antenna of FIG.

6 is a low VHF band and high VH in the antenna of FIG.
It is a directional characteristic figure of F band.

7 is a directional characteristic diagram of the UHF band in the antenna of FIG.

[Explanation of symbols]

2 Housing 4 VHF band receiving antenna 4a 4b Radiator 10a 10b 20a 20b Coaxial cable (transmission line) 12 2 Distributor (combiner) 16 UHF band receiving antenna radiator 16a 16b Radiator

Claims (8)

[Claims] 1. Two linear radiators arranged in parallel at a predetermined distance from each other, a combiner, and two radiators input to the combiner from a predetermined direction. Two transmission lines that are selected to have different lengths and that connect the two radiators and the combiner, so that the reception outputs based on the arriving radio waves have the same phase,
The phase difference feeding antenna in which the distance between the two radiators is selected to be shorter than λ (center wavelength of the two radiators) / 8. 2. The phase difference feeding antenna according to claim 1,
An antenna for receiving low VHF band and high VHF band television broadcasts, wherein the distance between the two radiators is about 100.
Phase difference feeding antenna which is mm. 3. The phase difference feeding antenna according to claim 1, wherein the two radiators are rod antennas. 4. The first and second radiators arranged in parallel, the first and second combiners, and the first and second radiators connected to the first combiner, The first and second transmission lines whose lengths are selected so that the radio waves arriving from the radiator side are combined in phase by the first combiner, and the first and second radiators are installed in the second combiner. The third and fourth transmission lines whose lengths are selected so that the radio waves arriving from the second radiator side are connected and are combined in phase with each other in the second combiner, and the first and second transmission lines are connected to each other. A state in which the third and fourth transmission lines are connected to the first combiner and separated from the second combiner;
And a switching means for switching one of the second transmission line separated from the first combiner and the third and fourth transmission lines connected to the second combiner. . 5. Two linear radiators having different center frequencies, a combiner, and reception outputs based on radio waves coming from a predetermined direction of the two radiators input to the combiner are in phase with each other. A phase difference feeding antenna, which is selected to have different lengths and includes two transmission lines that connect the two radiators and the combiner. 6. The phase difference feeding antenna according to claim 5, wherein the tip ends of the two radiators are respectively bent. 7. The phase difference feeding antenna according to claim 6, wherein the bending is performed in opposite directions. 8. A first and a second linear radiator, which are arranged in parallel with each other at a predetermined distance, a first combiner, and a first and a second input to this first combiner. The second radiators are selected to have different lengths so that the reception outputs based on the VHF band radio waves from the predetermined direction have the same phase,
A first transmission line and a second transmission line connecting the two radiators to the combiner;
VH that is λ (center wavelength of the two radiators) / 8 or less
The F-band receiving antenna, the third and fourth linear radiators having different center frequencies arranged in front of the first and second radiators, the second combiner, and the second radiator. 3rd and 4th input to the synthesizer of
Third radiators that are selected to have different lengths so that the reception outputs based on the UHF band radio waves arriving from the predetermined direction of the radiators may be in the same phase and that connect the two radiators and the combiner. And a fourth transmission line, and the third and fourth
And a UHF band receiving antenna in which both ends of the radiator are bent in mutually opposite directions.