JPH0554283B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a UHF and VHF antenna that can receive radio waves in the UHF and VHF bands with one antenna.

[Prior art]

Conventionally, the above-mentioned shared antenna includes one shown in FIG. 2, for example. This includes arm 1, reflector 2 for low VHF (90~108MHz), and reflector 2 for high VHF (90~108MHz).
Reflector 3 for VHF (170-222MHz), radiator 4 for VHF, radiator 5 for UHF, and waveguide 6, 6 for UHF
... are arranged in order, and these UHF waveguides 6, 6
... VHF/UHF composite waveguides 7, 7 are placed between them, and the VHF/UHF composite waveguides 7, 7 are
A phase coil 7b is provided between elements 7a, which have a half wavelength of the radio waves to be received in the UHF band.

In such an antenna, the VHF/UHF composite waveguide 7, 7 is used because it is a normal VHF antenna.
When a standard waveguide is used, its length is longer than that of a UHF waveguide, so this is to prevent it from operating as a reflector in the UHF band. That is, as shown in FIG. 3, in the composite waveguides 7, the electrical length of the elements 7a, 7a is approximately 1/2 wavelength of the received radio wave in the UHF band, and in the VHF band, the electrical length of the elements 7a, 7a is approximately 1/2 the wavelength of the received radio wave in the UHF band. Total electrical length including electrical length is VHF
It is designed to be approximately 1/2 the wavelength of the radio waves received in the band.

[Problem that the invention seeks to solve]

In the above shared antenna, when receiving VHF band radio waves, the composite waveguide 7,
Since the phase coil 7b is located in the center where the current distribution is large in 7, the effective current is small and the gain in the VHF band is smaller than that in the case where the composite waveguides 7, 7 are not used. Ta.

[Means for solving problems]

In order to solve the above problems, this invention has a VHF radiator, a UHF radiator, and a UHF waveguide installed in the same plane in order on the arm.
At least five waveguides are arranged at predetermined intervals. 2nd and 3rd one counting from the UHF radiator side
A non-composite VHF waveguide (without a phase coil etc. in the middle) is installed between the first UHF waveguide and between the fourth and fifth UHF waveguides. .

In this invention, the distance between the UHF waveguide and the VHF waveguide is further adjusted to match the receiving wavelength in UHF.
The length of the UHF waveguide is selected to be 0.4 to 0.45 times the receiving wavelength in UHF.

[Effect]

According to the present invention, since a non-composite type VHF waveguide is used, the gain in the VHF band is improved compared to one using a composite waveguide. These VHF waveguides are placed between the UHF waveguides, so
It acts as a reflector for the UHF band, reducing the gain, but the reduction in gain at the frequency to be received in the UHF band is relatively small.

This is because at the frequency to be received in the UHF band, radio waves pass close to the UHF waveguide while converging, so even if a VHF waveguide is inserted between the UHF waveguides, there is no reflection effect. This is because it becomes smaller;
Furthermore, at the frequency to be received, in addition to the waves traveling on the UHF waveguide array, there are also many waves traveling in the opposite direction, and due to interference between the two waves, the strong and weak electric fields are occurs between the waveguides for
This weak electric field is likely to occur between the second and third UHF waveguides and between the fourth and fifth waveguides, and the electric field is particularly weak between the VHF waveguide and the adjacent UHF waveguide. This is because the VHF waveguide is provided at a position where the distance from the VHF waveguide is 0.08 to 0.11 times the receiving wavelength of the UHF band. In addition, when the length of a UHF waveguide is set to 0.4 to 0.45 of the receiving wavelength,
Gain is greatest.

〔effect〕

As described above, according to the present invention, the gain in the VHF band is significantly improved compared to that using a composite waveguide, and the gain in the UHF band is almost the same as that using a composite waveguide. A common antenna for both UHF and VHF bands can be obtained. Moreover,
Since this invention does not use a composite waveguide for the VHF waveguide, there is no need for rivets or waterproof terminals to connect the elements that make up the composite waveguide and the phase coil, reducing costs. You can also do it.

〔Example〕

FIG. 1 shows an embodiment of the invention. In this example, for example, in the Hanshin region, 2, 4, 6, 8,
VHF television broadcasts on channels 10 and 12, and UHF television broadcasts on channel 19,
It is used to receive each of the above television broadcasts when they are transmitted from the same transmitting station. In Figure 1, 10 is an arm;
From one end side, low VHF reflector 12, high
VHF reflector 14, VHF radiator 16, UHF
A radiator 18 for UHF, waveguides 20, 20, . . . for UHF are arranged. This UHF waveguide 20 has 7
The length is selected to be 0.4 to 0.45 times the wavelength λ of the radio waves (19 channels in this embodiment) to be received in the UHF band.

Among these UHF waveguides 20, 20...
VHF waveguides 22, 22 are provided between the second and third and between the fourth and fifth as counted from the UHF radiator 18 side. The length of these VHF waveguides 22, 22 is selected for high VHF, and these VHF waveguides 22, 22
and the adjacent UHF waveguides 20, 20... are selected to be 0.08 to 0.11 times the above λ.

Curve A shown in Figure 4 is from the antenna in Figure 1.
UHF when VHF waveguides 22 and 22 are removed
This shows the relationship between frequency and gain in the band, and as is clear from this, it is a relatively wide band in which almost the same gain can be obtained for radio waves other than the radio waves to be received. UHF waveguide 20, 20...
The relationship between the frequency and gain in the UHF band when the VHF waveguides 22, 22 are provided at arbitrary positions between them is shown by curves B and C in the figure. As is clear from this, the gain is reduced by providing the VHF waveguides 22, 22, but the reduction in gain at the frequency of the radio waves to be received in the UHF band is the same as the gain at other frequencies. less than the drop. This is because, as mentioned above, the radio waves of the frequency to be received converge and pass closer to the UHF waveguides 20, 20..., so in the UHF band, the VHF waveguide acts as a reflector. 22, 22
This is because even if a signal is provided, the reflection effect will be small for the frequency to be received. The frequency and gain in the UHF band when the VHF waveguide 22 is provided between the second and third and between the fourth and fifth from the UHF radiator 18 as in this embodiment. The relationship is shown by curve D in the figure, and the relationship between frequency and gain of the antenna using the above-mentioned composite waveguide is shown by curve E. As is clear from the comparison of both curves D and E, the gain of the antenna in this example at the frequency to be received is only 1 dB lower than the gain at the frequency to be received by the antenna using the composite waveguide. It is.
As is clear from curves B and C, the decrease in gain is low at the frequency to be received, and there is a
This is because the VHF waveguides 22, 22 are placed between the 5th and 5th points in the portion where the electric field is weak, as shown in the section of the operation, to minimize the decrease in gain.
Furthermore, the length and length of the UHF waveguides 20, 20...
This is because the spacing between the VHF waveguides 22, 22 and the adjacent UHF waveguide 20 is selected as described above.

FIG. 5 shows the relationship between frequency and gain in the VHF band for the antenna of this embodiment and a conventional antenna using a composite waveguide, respectively, by curves F and G. As is clear from the comparison of both curves F and G, this embodiment has a larger gain. This is because the effective current is large because ordinary VHF waveguides 22, 22 are used instead of a composite waveguide.

As described above, according to the present invention, the gain in the VHF band is larger than that of the conventional shared antenna, and the gain in the UHF band is larger than that of the conventional shared antenna.
It is possible to provide an antenna in which the gain of one wave in the band is almost the same as that of a conventional antenna.

In the above embodiments reflectors for low and high VHF were provided, but in some cases these may not be necessary. Furthermore, the UHF waveguides 20, 20... are 7
Although this number is provided, the number can be increased or decreased as long as it is 5 or more.

[Brief explanation of the drawing]

FIG. 1 is a plan view of one embodiment of the UHF and VHF antenna according to the present invention, and FIG.
A plan view of an example of a UHF and VHF antenna, Fig. 3 is a schematic diagram of the composite waveguide used in the antenna of Fig. 2, and Fig. 4 shows the difference between this example and a conventional antenna in the UHF band. Frequency vs. Gain Characteristic Diagram FIG. 5 is a frequency vs. gain characteristic diagram of this embodiment and a conventional antenna in the VHF band. 10...Arm, 16...VHF radiator, 1
8...UHF radiator, 20...UHF waveguide,
22...VHF waveguide.

Claims (1)

[Claims] 1. An arm, a VHF radiator installed on this arm, a UHF radiator installed on the arm adjacent to the VHF radiator in the same plane, and a UHF radiator installed on the arm that is the same as the above UHF radiator. At least five UHF waveguides arranged adjacent to each other in a plane at a predetermined interval, and between the second and third UHF waveguides counting from the UHF radiator side; a non-composite VHF waveguide provided between the fourth and fifth UHF waveguides in the same plane;
The distance between the VHF waveguide and the adjacent UHF waveguide is 0.08 to 0.11 times the receiving wavelength in UHF, and the length of the UHF waveguide is 0.4 times the receiving wavelength in UHF. or 0.45 times
UHF and VHF common antenna.