JP2000269736A - Multifrequency band antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized antenna for multifrequency bands by providing a dipole antenna for a first frequency band, having a pair of bar-shaped elements which are almost linearly disposed and an antenna for a second frequency band higher than the first frequency band, one bar-shaped element of which is provided with a radiator. SOLUTION: This multifrequency band antenna has an antenna 2 for a first frequency reception, for example, a VHF band. This antenna 2 is a dipole antenna consisting of a pair of bar-shaped elements 2a and 2b arranged almost on the same straight line and the length of each element is selected to be shorter than 1/4 of a center wavelength λ of a reception frequency band for the VHF band and has directionality which mainly receives radio waves from a direction vertical to its length direction. Antennas (Yagi-type reception antennas) 8 and 10 for second frequency band reception, for example, for a UHF band, are installed on the upper surface of the bar-shaped elements 2a and 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-frequency band antenna capable of receiving radio waves in a plurality of different frequency bands.

[0002]

2. Description of the Related Art Generally, an antenna mounted on a vehicle or the like,
For example, a non-directional antenna may be used as an antenna for receiving a television broadcast mounted on a vehicle or the like. As the non-directional antenna, there are, for example, an altitude loop antenna and a clover leaf antenna.
Utilizing such an antenna, for example, VHF band and UH band
When receiving radio waves in the F band, these antennas are prepared for each frequency band.

[0003]

[0005] Alhode loop antennas and clover leaf antennas are both large in size. If these antennas are prepared for the VHF band and the UHF band, respectively, the number of parts increases and the production is troublesome. In addition, it becomes large. In addition, omnidirectional antennas
Unwanted radio waves were easily received, and when used for receiving television broadcasts, ghosts were likely to occur.

An object of the present invention is to provide a small multi-frequency antenna. It is another object of the present invention to provide an antenna which is hard to receive unnecessary radio waves and can receive radio waves in a range close to non-directionality.

[0005]

Means for Solving the Problems In order to solve the above problems, one embodiment of the multi-frequency band antenna according to the present invention is as follows.
A first frequency band dipole antenna having a pair of rod-shaped elements arranged substantially linearly, and a radiator provided on at least one of the rod-shaped elements.
And a Yagi-type antenna for a second frequency band higher than the frequency band No. 2. The first frequency band is, for example, a VHF band, and the second frequency band is, for example, a UHF band.
There is a belt. The Yagi-shaped antenna for the second frequency band may include a director or a reflector or both a director and a reflector in addition to the radiator. The radiator for the second frequency band includes a pair of rod-like elements each having a predetermined angle,
For example, it can be attached at 90 degrees. The radiator may be a folded dipole antenna. It is desirable that the folded dipole antenna is arranged such that the center in the length direction is located on the rod-shaped element. The radiator for the second frequency band is
It may be a flat plate type.

In this aspect, since the radiator for the second frequency band is provided in the dipole antenna for the first frequency band, the antennas are separately manufactured for the first and second frequency bands. There is no need to provide a small multi-frequency band antenna. Moreover, since the radiator for the second frequency band is provided in the dipole antenna for the first frequency band, the radiator functions as a capacitive element for the dipole antenna for the first frequency band. . Therefore,
The length of the dipole antenna for the first frequency band can be made shorter than the originally required length, and a more compact multi-frequency band antenna can be obtained. When a folded dipole antenna is used as the radiator for the second frequency band, the folded dipole antenna
Even if a conductive rod-shaped member, for example, a rod-shaped element is passed through the central portion, the characteristics of the antenna for the second frequency band are not significantly affected.

[0007] A plurality of dipole antennas for the first frequency band can be provided. In this case, the rod-shaped elements of the dipole antennas for different first frequency bands are radially arranged from the same center. A plurality of Yagi-type antennas for the second frequency band are also provided, and each radiator of these Yagi-type antennas is formed as a rod-shaped element of a plurality of dipole antennas for the first frequency band. The radiator may be provided on each of the bar-shaped elements of at least one first frequency band dipole antenna, or may be provided on each of the Yagi-shaped antennas for different first frequency bands. Selection means for selecting the output of the dipole antenna for the first frequency band and the output of the antenna for the second frequency band is provided. This selection may select one antenna output or select a plurality of antenna outputs simultaneously.

With this configuration, the antennas for the first frequency band have different directivities, so that the antenna for the first frequency band is selected by the selection means, so that the antenna for any one of the first frequency bands can be selected. , It is possible to receive even the first frequency band of radio waves arriving from, and it is possible to reduce ghosts even when used for receiving a television broadcast as compared with the case where an omnidirectional antenna is used. Similarly, since the antennas for the second frequency band also have different directivities, by selecting the antenna for the second frequency band by the selection means, the second antenna arriving from any direction can be obtained. Radio waves in the frequency band can be received, and even when used for receiving television broadcasts, ghosts can be reduced as compared with the case where an omnidirectional antenna is used. Therefore, in addition to being compact, it can receive radio waves arriving from any direction in two frequency bands, and when used for receiving television broadcasts, it is possible to realize a multi-frequency band antenna in which ghost is unlikely to occur. .

Another embodiment of the multi-frequency band switching antenna according to the present invention comprises a Yagi antenna for a first frequency band having at least one director. Further, a plurality of Yagi antennas for a second frequency band higher than the first frequency band are provided. These Yagi-type antennas are provided with a plurality of radiators in a director. The Yagi antenna for the first frequency band may include a plurality of directors.
The plurality of radiators for the second frequency band can be provided in one director, or can be provided in different directors. The Yagi antenna for the first frequency band includes a radiator. Further, the antenna may include a reflector.

[0010] Also in this embodiment, since a plurality of Yagi-type antenna radiators for the second frequency band are provided in the director of the Yagi-type antenna for the first frequency band, a small multi-frequency band radiator is used. An antenna can be realized. Moreover, since the radiator of the Yagi-type antenna for the second frequency band functions as a capacitive element with respect to the director of the Yagi-type antenna for the first frequency band, the Yagi-type antenna for the first frequency band is used. The director of the antenna can be shortened, and the size can be reduced.
In addition, since a plurality of Yagi-type antennas for the second frequency band are provided, it is possible to perform diversity reception using these antennas.

Another aspect of the multi-frequency band antenna of the present invention is a first frequency band antenna having a pair of rod-shaped elements attached to an arm, and substantially parallel to the pair of rod-shaped elements. Thus, a second frequency having a radiator for a second frequency band higher than the first frequency band, usable as a director of an antenna for the first frequency band, mounted on the arm. With an antenna for the band,
I have it.

According to this aspect, since the radiator of the antenna for the second frequency band and the pair of rod-shaped elements are provided on the arm of the antenna for the first frequency band, a small multi-frequency antenna is provided. A band antenna can be realized. Moreover, the radiator for the second frequency band is provided in parallel with the pair of rod-shaped elements of the antenna for the first frequency band,
In addition, since the antenna functions as a director of the antenna for the first frequency band, the directivity of the antenna for the first frequency band can be improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multi-frequency band antenna according to a first embodiment of the present invention has a first antenna as shown in FIGS.
Antenna for receiving a frequency band of, for example, VHF band
have. This antenna 2 is a dipole antenna composed of a pair of rod-shaped elements 2a and 2b arranged on substantially the same straight line. The rod-shaped elements 2a, 2b
It is made of a conductive material and is made of, for example, metal. The length of each of the rod-shaped elements 2a and 2b is selected to be shorter than １ ／ of the center wavelength λ of the reception frequency band in the VHF band. The VHF band receiving antenna 2 has directivity for mainly receiving radio waves from a direction perpendicular to the length direction of the rod-shaped elements 2a and 2b. The inner ends of these rod-shaped elements 2a and 2b are used as a power supply unit, and this power supply unit is connected to a coaxial cable 6 via a balun 4.

On the upper surfaces of the rod-shaped elements 2a and 2b, Yagi-type receiving antennas 8 and 10 for receiving a second frequency band, for example, for receiving UHF bands are mounted. These Yagi-type receiving antennas 8, 10 have radiators 8a, 10a, which are mounted at positions offset toward the outer ends of the upper surfaces of the rod-shaped elements 2a, 2b. Each of these radiators 8a and 10a is configured by a flat folded dipole antenna. These radiators 8a, 10a
Has a length dimension L (this L is formed to be half the center wavelength λ of the reception frequency band of the UHF band) and is orthogonal to the rod-shaped elements 2a and 2b. Are located. In this arrangement, radiators 8a, 10
The center of a is in contact with the rod-shaped elements 2a, 2b.

The UHF band waveguides 8b and 10b are mounted on the upper surfaces of the outer ends of the rod elements 2a and 2b. Each of the directors 8b and 10b has a length determined by the relationship with the reception frequency.

The radiator 8a and the director 8b form one Yagi-type antenna 8, and the radiator 8b and the director 10a form another Yagi-type antenna 10. The UHF band director 8
The distance between b and 10b and radiators 8a and 10a is determined in the same manner as a normal Yagi antenna. The Yagi-type antenna 8 mainly receives radio waves from outside of the director 8b, that is, from the left side in FIGS. 1 and 2, and the Yagi-type antenna 10 is outside of the director 10b, ie, It has directivity for mainly receiving radio waves from the right in FIGS. 1 and 2.

The radiator 8a has a feeding portion at an inner end on the folded side, which is connected to a coaxial cable 18 via a balun 16. Similarly, in radiator 10a, the inner end on the folded side is used as a power supply unit, and is connected to a coaxial cable via a balun, though not shown. The radiators 8a and 10a are sandwiched between the
b, a reflector can be provided on the side opposite to 10b,
The number of directors can be increased.

In the multi-frequency band antenna thus configured, the rod-shaped element 2 of the VHF band reception antenna 2 is used.
a and 2b are used in place of the arms of the UHF band receiving antennas 8 and 10. At this time, in order to prevent the UHF band receiving antennas 8 and 10 from being significantly affected by the VHF band receiving antennas 2, folded dipole antennas are provided on the radiators 8a and 10a of the UHF band receiving antennas 8 and 10. I'm using This means that if the antenna is a folded dipole antenna, the UHF band receiving antennas 8 and 10 will not be affected so much even if metal rods as the rod-shaped elements 2a and 2b of the VHF band receiving antenna 2 pass through the center of the folded dipole antenna. This is because the power supply portions are located on both sides of the rod-shaped elements 2a and 2b, and can easily supply power.

The radiators 8a and 10a and the directors 8b and 10b of the UHF band receiving antennas 8 and 10 are provided in direct contact with the tip ends of the rod-shaped elements 2a and 2b of the VHF band receiving antenna 2. Therefore, these function as capacitance elements. Therefore, the rod-shaped elements 2a, 2
The length of b can be made shorter than originally required,
The VHF band receiving antenna 2 can be reduced in size.
In addition, as described above, the radiators 8a and 10a and the directors 8b and 10b of the UHF band receiving antennas 8 and 10 are provided.
Are the rod-shaped elements 2a, 2 of the VHF band receiving antenna 2.
Since the antenna is disposed above the antenna b, the arms for supporting the radiators 8a and 10a and the directors 8b and 10b are unnecessary, and the UHF band receiving antenna can be reduced in size. In addition, since the radiators 8a and 10a are formed in a flat plate shape, the size of the UHF band receiving antennas 8 and 10 can be further reduced. Thus, the UHF band receiving antennas 8, 10,.
Since each of the VHF band receiving antennas 2 is miniaturized, a small multi-frequency band antenna can be obtained as a whole.

FIGS. 3 to 5 show a multi-frequency band antenna according to a second embodiment of the present invention. As shown in FIG. 3, this multi-frequency band antenna has a plurality of, for example, two VHF antennas.
Band receiving antennas 20 and 22 are provided. The VHF band receiving antenna 20 has conductive rod-shaped elements 20a and 20b arranged substantially in a straight line. Similarly, the VHF band receiving antenna 22 intersects with the rod-shaped elements 20a and 20b of the VHF band receiving antenna 20,
For example, the rod-shaped elements 22a and 22b are arranged substantially linearly so as to be orthogonal to each other. That is, the rod-shaped elements 20a, 20b, 22a, and 22b are arranged radially outward from the respective inner ends at a predetermined angle, for example, 90 degrees. The two dipole antennas 20 and 22 constitute a so-called cross dipole antenna. Although not shown, the dipole antennas 20 and 22 are individually supplied with power to the inner ends thereof via coaxial cables via baluns.

Each rod-like element 20a, 20b, 22
a, 22b, a total of four UHF band receiving antennas 2
4, 26, 28, 30 are attached. These U
The HF band receiving antennas 24, 26, 28, and 30 have directors 24a, 26a, 28a, and 30a at outer ends of the rod-shaped elements 20a, 20b, 22a, and 22b.

These directors 24a, 26a, 28a, 3
A little inside of Oa, radiators 24b, 26b, 28
b, 30b are rod-shaped elements 20a, 20b, 22a,
22b. Each of the radiators 24b, 26b, 28b, and 30b uses a folded dipole for the same reason as the radiator of the first embodiment, and is a flat plate.

Each radiator 24b, 26b, 28b,
The reflectors 24c, 2c
6c, 28c, 30c are attached. The ends of the reflectors 24c, 26c, 28c, 30c are in contact with the adjacent reflectors 24c, 26c, 28c, 30c. Since they are in contact with each other, they are insulated by the rod elements 20a, 20b, 22a, 22b and the insulator 23. Radiator 24c, 2
When 6c, 28c, and 30c are not in contact with each other, the insulator 23 is unnecessary. The reflectors 24c, 26c,
28c and 30c can be optionally removed.

Although not shown, the radiators 24b, 26b, of the respective UHF band receiving antennas 24, 26, 28, 30
28b and 30b are connected to coaxial cables via baluns, respectively, as in the radiator of the first embodiment.
Power is being supplied. Thus, each UHF band receiving antenna 24, 26, 28, 30 is connected to the VHF band receiving antenna 2
Since it is provided on the rod elements 0 and 22,
In addition to miniaturization, the UHF band receiving antennas 24, 26, 28, and 30 function as capacitive elements, so that the length of the rod-shaped element can be made shorter than originally required, and the size can be further reduced. Can be achieved.

The VHF band receiving antenna 20 mainly receives radio waves from directions indicated by arrows a and b in FIG. Similarly, the VHF band receiving antenna 22 mainly receives radio waves from directions indicated by arrows c and d. In addition, these two VHF
By combining the output signals of the band receiving antennas 20 and 22 and adjusting the phase, it is possible to mainly receive radio waves from directions indicated by arrows e, f, g, and h.

The UHF band receiving antenna 24 mainly receives radio waves from the direction indicated by the arrow A in FIG. Similarly, the UHF band receiving antenna 26 mainly receives radio waves from the direction indicated by the arrow B. The UHF band receiving antenna 28 mainly receives radio waves from the direction of arrow C. UHF
The band receiving antenna 30 mainly receives radio waves from the direction of arrow D.

By combining the outputs of the UHF band receiving antennas 24 and 28 and adjusting the phase, radio waves from the direction of arrow E can be mainly received. By combining the outputs and adjusting the phase, radio waves from the direction of arrow F can be mainly received. By combining the outputs of the UHF band receiving antennas 24 and 30 and adjusting the phase, the direction of the arrow H can be adjusted. , And by combining the outputs of the UHF band receiving antennas 26 and 28 and adjusting the phase, it is possible to mainly receive the radio wave mainly from the direction of arrow G.

As described above, by appropriately combining the outputs of the antennas and adjusting the phase, whether in the VHF band or the UHF band, it is possible to receive radio waves from any direction, Despite the use of omni-directional antenna, it can be made directional close to omni-directional, and even when used for television broadcast reception, the ghost compared to the case using omni-directional antenna Less affected.

Therefore, as shown in FIG. 5, the reception outputs of the VHF band receiving antennas 20 and 22 are
4 and is synthesized by the synthesizer 36.
Similarly, each UHF band receiving antenna 24, 26, 28,
The received output of 30 is amplified by amplifiers 38, 40, 42, 44 and combined by combiner 46. The combined outputs of the combiners 36 and 46 are mixed by a mixer 48, amplified by an amplifier 50, and supplied via a DC blocking capacitor 52 and an output terminal 54 to an input terminal 56 provided indoors or inside the moving body. Then, it is supplied to a television receiver (not shown) via a DC blocking capacitor 58.

The above-mentioned amplifiers 32, 34, 38, 40, 42, 4 provided indoors or inside a moving body are provided.
DC power supply 60 for supplying operating voltages to 4, 50, etc.
Is provided. The DC voltage from the DC power supply 60 is supplied to the output terminal 54 via the high-frequency blocking coil 62 and the input terminal 56, and the amplifiers 32, 34, 38, 40, 42, 4
4, 50.

A selection means, for example, a directivity control pulse generator 64 is also provided in the indoor or moving body. The directivity control pulse generated by this means is supplied to a high-frequency blocking coil 62, an input terminal 56, an output The signal is supplied to the switching control circuit 68 via the terminal 54 and the high frequency blocking coil 66.

Although not shown, the directivity control pulse generator 64 has a VHF band directivity changeover switch and a UHF band directivity changeover switch. The UHF band directivity changeover switch has a changeover contact corresponding to each of the directions A to H shown in FIG. 4B and a contact that can arbitrarily contact one of these contacts. Generates a pulse signal corresponding to the switching contact position contacted by.

When this pulse signal is supplied to the switching control circuit 68, the switching control circuit 68 causes the amplifiers 38, 40, 42, and 42 to receive radio waves from the direction indicated by the supplied pulse signal.
One or two of the 44 outputs are selected and provided to combiner 46. The VHF band directivity changeover switch is similarly configured.

FIGS. 6 and 7 show the VHF at about 47 MHz to 68 MHz in this multi-frequency band antenna.
4 shows frequency versus gain characteristics of a band antenna. However, FIG.
Is for one VHF band receiving antenna, and FIG.
The output of two VHF band antennas is combined.
8 and 9 are directional characteristics diagrams of a VHF band receiving antenna at an arbitrary frequency of about 47 MHz to 68 MHz. FIG. 8 shows a case of one antenna, and FIG. 9 shows a result of combining outputs of two antennas. is there. It is clear that the directivity is changed by this combination.

FIG. 10 and FIG.
5 shows frequency versus gain characteristics of a VHF band antenna at 8 MHz. However, FIG. 10 shows the case of one VHF band receiving antenna, and FIG. 11 shows the result of combining the outputs of two VHF band antennas. FIG. 12 and FIG.
FIG. 12 is a directional characteristic diagram of a VHF band receiving antenna at an arbitrary frequency from Hz to 108 MHz. FIG. 12 shows a case of one antenna, and FIG. 13 shows a result of combining outputs of two antennas. It is clear that the directivity is changed by this combination.

FIGS. 14 and 15 show the frequency versus gain characteristics of the VHF band antenna from about 170 MHz to 230 MHz. However, FIG. 14 is for one VHF band receiving antenna, and FIG. 15 is for combining the outputs of two VHF band antennas. 16 and 17 are directional characteristics diagrams of a VHF band receiving antenna at an arbitrary frequency of about 170 MHz to 230 MHz. FIG. 16 shows one antenna, and FIG. 17 shows a combination of outputs of two antennas. is there. It is clear that the directivity is changed by this combination.

FIG. 18 shows that about 470 MHz to 890 MHz.
5 shows the frequency versus gain characteristics of the UHF band antenna in FIG.
However, it is for one UHF band receiving antenna.
FIG. 19 is a directional characteristic diagram of the UHF band receiving antenna at an arbitrary frequency of about 470 MHz to 890 MHz. However, it is for one UHF band receiving antenna.

FIG. 20 shows a multi-frequency band antenna according to a third embodiment of the present invention. In the second embodiment, VH
Since two dipole antennas orthogonal to the F band receiving antenna were used, the number of UHF band receiving antennas that can be provided on these rod-shaped elements was also limited to four. Therefore, it is necessary to use a UHF band receiving antenna having a relatively wide directivity, and there is a possibility that an improvement in gain cannot be expected.

Therefore, in the multi-frequency band antenna of the third embodiment, a plurality of VHF band receiving dipole antennas 70 are connected to the respective bar-shaped elements 70a, 70a.
Are radially arranged so as to form an angle smaller than 90 degrees with the rod-shaped element of the adjacent VHF band dipole antenna for reception. Each of these rod-shaped elements 7
Are formed on the outer end sides of Oa, 70a,... For receiving UHF bands, respectively. Yagi type antenna 72 for receiving these UHF bands,
72 are provided with a director 72a, a radiator 72b, and a reflector 72c, respectively, as in the above-described second embodiment. Of course, radiator 72b is a flat folded dipole antenna.

By providing a plurality of directors 72a, the directivity is narrow and the gain is high. Although not shown, similarly to the second embodiment, a switching control circuit and a directivity control pulse generator are provided, and directivity is switched. The reflector 72c can be removed in some cases. Also in this case, downsizing can be achieved similarly to the multi-frequency band antenna of the second embodiment.

FIG. 21 shows a multi-frequency band antenna according to a fourth embodiment of the present invention. This multi-frequency band antenna is provided with a VHF band receiving Yagi-shaped antenna 80. The Yagi-shaped antenna 80 includes a plurality of, for example, three directors 84 and one radiator 86 on an arm 82.
This is a normal one provided with one reflector 88. In addition,
The arm 82 is supported by a column 90.

On each of these three directors 84,
A total of six Yagi-type antennas 92 for UHF band reception
Is arranged. Each of these Yagi-type antennas 92 has a director 92a on the outside, a radiator 92b formed of a flat folded dipole inside the director 92a, and a reflector 92c inside the director 92a. Things.
The radiator 92b is electrically insulated from the director 84.

In this multi-frequency band antenna, UHF band receiving Yagi-shaped antennas 92 are arranged at regular intervals along arm 82 and have directivity on both sides of arm 82 as indicated by arrows. Therefore, the Yagi-type antenna 92 for UHF band reception can be used as the diversity reception antenna. The VHF band receiving antenna 80 is used to receive a radio wave arriving from the director 84 in a direction along the arm 82. Needless to say, this multi-frequency band antenna can be downsized similarly to the multi-frequency band antennas of the first to third embodiments.

FIG. 22 shows a multi-frequency band antenna according to a fifth embodiment of the present invention. In the fourth embodiment, UH
Since the F-band receiving antenna is provided in the director of the VHF-band receiving antenna, the directivity is almost perpendicular to the VHF-band receiving antenna. In the multi-frequency band antenna according to the fifth embodiment, the directivity is substantially the same in the VHF band and the UHF band.

The multi-frequency band antenna of this embodiment has a VHF band receiving antenna 100. The antenna 100 has a radiator 104 mounted on an arm 102. The radiator 104 is provided with a UHF band receiving antenna 10
6 is attached. The director 108 of the UHF band receiving antenna 106 has a VHF
It is attached in parallel with radiator 104 of band receiving antenna 100. Radiator 110 is attached at a position inside this. This radiator 110 is also a folded flat dipole, similar to the antenna for the multi-frequency band of the other embodiments, and is substantially parallel to radiator 104 of the VHF band, and the central portion thereof contacts arm 102. And so on. U is located at a position inside the radiator 110 and outside the radiator 104 in the VHF band.
A reflector 112 for the HF band is provided in parallel with the radiator 104 in the VHF band. The director 10 for these UHF bands
8. The radiator 110 and the reflector 112 can be used as the director of the antenna 100 in the VHF band.
Dimensions and arrangement positions are determined.

Thus, when radio waves in the UHF band and the VHF band arrive from the same direction, both radio waves can be received well, and the antenna in the UHF band functions as a director of the antenna in the VHF band. , VHF band gain can be improved. The director 108 and the reflector 1
12 can optionally be removed. Conversely, the number of directors 108 can be increased. Also in this case, since the arm 102 can be commonly used for the antennas in the VHF band and the UHF band, the size can be reduced.

In the first to fourth embodiments, U
The HF band radiator is mounted in direct contact with the VHF band rod-shaped element. This is to shorten the length of the rod-shaped element. However, when the length of the rod-shaped element is originally required, the radiator in the UHF band is brought into contact with the rod-shaped element via an insulator. I just need.

[0048]

As described above, according to the present invention, a compact multi-frequency band antenna can be realized. Further, by switching a plurality of antennas, it is possible to provide a directional characteristic close to non-directionality.

[Brief description of the drawings]

FIG. 1 is a plan view of a multi-frequency band antenna according to a first embodiment of the present invention.

FIG. 2 is a side view of the multi-frequency band antenna of FIG. 1;

FIG. 3 is a plan view of a multi-frequency band antenna according to a second embodiment of the present invention.

FIG. 4 is a diagram showing the directivity of the multi-frequency band antenna of FIG. 3 in each VHF band and UHF band.

FIG. 5 is a block diagram of the multi-frequency band antenna of FIG. 3;

6 is a diagram showing one frequency vs. gain characteristic of a VHF band antenna at about 47 MHz to 68 MHz of the multi-frequency band antenna of FIG. 3;

7 is a diagram showing two combined frequency-gain characteristics of a VHF band antenna at about 47 MHz to 68 MHz of the multi-frequency band antenna of FIG. 3;

8 is a directional characteristic diagram of one VHF band receiving antenna at an arbitrary frequency of about 47 MHz to 68 MHz of the multi-frequency band antenna of FIG. 3;

9 is a combined directional characteristic diagram of two VHF band receiving antennas at an arbitrary frequency of about 47 MHz to 68 MHz of the multi-frequency band antenna of FIG. 3;

10 is about 75 MHz of the multi-frequency band antenna of FIG. 3;
FIG. 7 is a diagram showing frequency versus gain characteristics of one VHF band antenna from to 108 MHz.

FIG. 11 shows about 75 MHz of the multi-frequency band antenna of FIG. 3;
FIG. 7 is a diagram illustrating frequency vs. gain characteristics of two VHF band antennas in a frequency range from to 108 MHz.

FIG. 12 shows about 75 MHz of the multi-frequency band antenna of FIG. 3;
One VHF at any frequency from 108 MHz
FIG. 4 is a directional characteristic diagram of a band receiving antenna.

13 is about 75 MHz of the multi-frequency band antenna of FIG. 3;
Two VHFs at any frequency from 108 MHz
FIG. 4 is a directional characteristic diagram of a band receiving antenna.

FIG. 14 shows a multi-frequency band antenna of FIG.
FIG. 7 is a diagram illustrating frequency versus gain characteristics of one VHF band antenna from z to 230 MHz.

FIG. 15 shows about 170 MHz of the multi-frequency band antenna of FIG. 3;
FIG. 7 is a diagram illustrating frequency versus gain characteristics of two VHF band antennas from z to 230 MHz.

FIG. 16 shows about 170 MHz of the multi-frequency band antenna of FIG. 3;
One VH at any frequency from z to 230 MHz
It is a figure showing the directivity characteristics of the antenna for F band reception.

17 is a diagram of the multi-frequency band antenna of FIG.
Two VHs at any frequency from z to 230 MHz
It is a figure showing the directivity characteristics of the antenna for F band reception.

18 is about 470 MHz of the multi-frequency band antenna of FIG. 3;
FIG. 9 is a diagram illustrating frequency versus gain characteristics of one UHF band antenna from z to 890 MHz.

19 is about 470 MHz of the multi-frequency band antenna of FIG. 3;
One UH at any frequency from z to 890 MHz
FIG. 4 is a directional characteristic diagram of an F-band receiving antenna.

FIG. 20 is a plan view of a multi-frequency band antenna according to a third embodiment of the present invention.

FIG. 21 is a plan view of a multi-frequency band antenna according to a fourth embodiment of the present invention.

FIG. 22 is a plan view of a multi-frequency band antenna according to a fifth embodiment of the present invention.

[Explanation of symbols]

2 VHF band antenna (first frequency band antenna) 2a 2b Rod element 8 10 UHF band antenna (second frequency band antenna) 8a 10a radiator

Claims (5)

[Claims] 1. A dipole antenna for a first frequency band having a pair of rod-like elements arranged substantially linearly, and a first frequency band in which a radiator is provided on at least one of the rod-like elements. And a Yagi-shaped antenna for the second frequency band, which is also higher. 2. The multi-frequency band antenna according to claim 1, wherein the radiator is a folded dipole antenna. 3. The multi-frequency band antenna according to claim 1, wherein the plurality of first frequency band dipole antennas have their respective rod-like elements radially arranged from the same center, and the plurality of second frequency band dipole antennas. Each radiator of the Yagi-type antenna for the frequency band is formed in a plurality of rod-shaped elements of the dipole antenna for the first frequency band, and selects the output of the dipole antenna for the first frequency band, and A multi-frequency band antenna, wherein selection means for selecting an output of the frequency band antenna is provided. 4. A Yagi antenna for a first frequency band having at least one director, and a radiator provided in the director for a second frequency band higher than the first frequency band. And a plurality of Yagi-type antennas. 5. An antenna for a first frequency band having a pair of rod elements attached to an arm, and a first antenna attached to the arm so as to be substantially parallel to the pair of rod elements. A second frequency band having a radiator for a second frequency band higher than the first frequency band, which can be used as a director of the antenna for the second frequency band. Antenna.