JPH032983Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a wideband receiving antenna device including FM broadcasting.

Conventionally, this type of wideband receiving antenna device was designed to receive audio from FM broadcasts.
I haven't found anything that has been particularly scrutinized, but as shown in Figure 1, a folded radiator 1 for a VHF band receiving antenna is used.
The main purpose is to expand the operating frequency by changing the length of the radiator 1 and reflector 2 (about 20%) along with adjusting the load impedance, and basically it is used for FM broadcasting,
There are no antennas designed for the frequency bands of VHF television broadcasting and UHF television broadcasting.

On the other hand, the actual reception status is FM/
There are performance issues with TV shared receiving antennas, and there are very few of them, and most of them have a dedicated FM receiving antenna attached to the same mast or a separate mast.

Furthermore, even though some FM broadcast enthusiasts would like to install a dedicated antenna, it is thought that there are quite a number of them who are unable to install one due to issues such as price and space. This idea was made in view of the above circumstances, and its purpose is to provide a receiving antenna device that is inexpensive and easy to handle, which can receive VHF/UHF television broadcasts and FM broadcasts with a single antenna. be.

An embodiment of this invention will be described above with reference to the drawings. FIG. 2 shows the configuration of a radiator used in the receiving antenna device of this invention. This radiator has an operating frequency of 76~108MHz (FM broadcast,
The first radiating element 11 has an operating frequency of 170-222MHz (for VHF-band television broadcasting high-frequency range), and the second radiating element 12 has an operating frequency of 470-770MHz (for UHF-band television broadcasting). It is configured by a third radiating element 13 (for broadcasting). These first, second and third radiating elements 1
The lengths of Nos. 1 to 13 are approximately half the wavelength of the center frequencies of 92 MHz, 196 MHz, and 620 MHz at the respective operating frequencies.

In addition, the first radiating element 11 and the second radiating element 1
The element spacing between the second radiating element 12 and the second radiating element 12 is approximately 1/10 wavelength of the operating center frequency of the second radiating element 12.
The element spacing between the third radiating element 13 and the third radiating element 13 is approximately 1/10 wavelength of the operating center frequency of the third radiating element 13. Furthermore, regarding the phases of the feeding points of the first, second, and third radiating elements 11 to 13, in order to set the feeding phase between the elements to approximately 135°, the feeding line length, that is, the feeding phase difference, is set to 135°. The reason for this is to increase the radiation efficiency (finger directivity) (to make the radiating section directional), and the power to the second radiator 12 is fed to the first radiating element. 11 so that the phase (difference) is 135°. The frequency in this case is the operating center frequency of the second radiating element 12, and specifically, when the wavelength of this frequency is λm, the element spacing is slightly longer by an amount corresponding to (3/8)λm. However, the feeding phase of the second radiator 12 is delayed by 135 degrees.

Similarly, the power supply to the third radiator 13 is made to have a phase (difference) of 135° with respect to the second radiating element 12. The frequency in this case is the third radiating element 1
Specifically, when the wavelength of this frequency is λn, a line length difference corresponding to (3/8)λn is provided. That is, in FIG. 7, the second radiating element 12 from the combining point 27
The length of the third feeder line is made longer than the length of the feeder line by an amount corresponding to (3/8)λn, and the feed phase of the third radiating element 13 is delayed by 135°.

Note that this antenna device can be said to be a phase difference feeding array antenna configured of radiating elements having different tuning frequencies that are simultaneously fed.

FIGS. 3a to 3c show the directivity characteristics of a single radiator having such a configuration. Figure 3 a is the frequency
This shows the directional characteristics of the first radiating element 11 at 76 to 108 MHz, in this case, the second and third radiating elements
Since the radiating elements 12 and 13 are minute dipoles, there is almost no effect, and the directivity characteristics of a half-wavelength dipole can be obtained. Figure 3b shows frequency 170
It shows the directivity characteristics of the second radiating element 12 at ~222MHz. In this case, since it becomes a two-element array with minute intervals, unidirectionality can be obtained. FIG. 3c shows the directivity characteristics of the third radiating element 13 at a frequency of 470 to 770 MHz, and unidirectionality is similarly obtained in this case.

By using such a unidirectional radiator as a Yagi-type array, that is, by adding a waveguide element and a reflecting element that operate in each of the three frequency bands to this radiator, it can be configured as an array antenna. As a result, a Yagi antenna with even better characteristics can be obtained.

Figure 4 shows the equivalent circuit of the above radiator.
The input impedance is obtained by connecting the impedances of each dipole element in parallel, and if this is expressed in terms of admittance, it can be expressed by the following equation.

Yin=[(Y ₁₁ +Y ₁₂ +Y ₁₃ )+(Y ₂₁ +Y ₂₂ +Y ₂₃ )+
(Y ₃₁ + Y ₃₂ + Y ₃₃ )] …(1) Here, Y ₁₁ : Admittance due to the first radiating element 11, Y ₂₂ : Admittance due to the second radiating element 12, Y ₃₃ : Admittance due to the third radiating element 13. In admittance, Z ₁₁ = 1/Y ₁₁ , Z ₂₂ = 1/
Y ₂₂ , Z ₃₃ = 1/Y ₃₃ . Y ₁₂ = Y ₂₁ : Mutual admittance between the first and second elements, Y ₂ = Y ₃₂ : Mutual admittance between the second and third elements, Y ₁₃ =
Y ₃₁ : Mutual admittance between the first and third elements.

Furthermore, the actually obtained impedance standing wave ratio (VSWR) characteristics are shown in FIG.
That is, in equation (1), the respective impedances are such that the third radiating element 13 has a frequency approximately three times that of the second radiating element 12, and the second radiating element 12 has a frequency approximately three times that of the first radiating element 12.
The number of radiation elements 11 is approximately twice as large as that of the radiating element 11, and since it is represented by a combination circuit of high impedance and low impedance, the characteristics shown in FIG. 5 are obtained as actual measured values.

FIG. 6 shows a Yagi antenna constructed using the above broadband radiator. In the same figure,
14 is the second radiating element 12 and the third radiating element 1
3 feeder line, 15 is the first waveguide element for the frequency band of 76-108MHz, 16 is the second waveguide element for the frequency band of 170-222MHz, and 17 is the first waveguide element for the frequency band of 470-770MHz. 3 waveguide element, 18 is the first reflection element for the frequency band of 76~108MHz, 19 is 170~222M
A second reflective element for the Hz frequency band, 20 from 470
3rd reflective element for the 770MHz frequency band, 21 is the antenna mast, 22 is the antenna boom, 23 is the arm for the second reflective element, 24 is the arm for the third reflective element 13, 25 is the first radiation Reference numeral 26 indicates a power feeding section for the element 11, and a power feeding section for the second radiating element 12 and the third radiating element 13, respectively. In this Yagi type antenna, the radiator is the feeding section 25, 2
In order to make the case No. 6 compact, the second radiating element 12 and the third radiating element 13 are integrated and incorporated, and are connected to the first radiating element 11 by a power feeding section 14. Furthermore, mixers for combining the outputs of the first radiating element 11, the second radiating element 12, and the third radiating element 13 are provided in the cases of the power feeding units 25 and 26, respectively. FIG. 7 shows its configuration. That is, the second radiating element 1
The outputs of the second and third radiating elements 13 are combined by a mixer 27, and the outputs of the mixer 27 and the outputs of the first radiating element 11 are combined by a mixer 28 and guided to a receiver.

As described above, the receiving antenna device of this invention can handle VHF/UHF television broadcasting with a single antenna.
Since it can receive FM broadcasts, it is inexpensive and easy to handle.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a radiator in a conventional receiving antenna, Fig. 2 is a schematic diagram of a radiator according to an embodiment of the invention, Figs. Figure 4 is an equivalent circuit diagram, Figure 5 is an impedance standing wave ratio characteristic diagram, Figure 6 is a perspective view of a Yagi antenna using the above radiator, and Figure 7 is a power supply system diagram for the above antenna. be. DESCRIPTION OF SYMBOLS 11... First radiating element, 12... Second radiating element, 13... Third radiating element, 14... Feeding line, 15... First waveguide element, 16... Second guiding element Wave element, 17...Third waveguide element, 18...First
reflective element, 19... second reflective element, 20...
Third reflective element.

Claims (1)

[Scope of utility model registration request] Frequency band 76~108MHz, 170~222MHz and 470MHz
When the respective center wavelengths of ~770MHz are λ ₀₁ , λ ₀₂ and λ ₀₃ , the first radiator consists of a dipole antenna with a length of λ ₀₁ /2, and the dipole with a length of λ ₀₂ /2. a second radiator configured with an antenna; a third radiator configured with a dipole antenna having a length of λ ₀₃ /2; First,
a second and a third waveguide, and a reflector that operates in correspondence with each of the first, second and third radiators, the first radiator and the second radiator; and the distance between the second radiator and the third radiator is λ ₀₂ /10, and the waveguide and the radiator are attached to one arm to form _a Yagi antenna. , the feeding phase of the second radiator with respect to the first radiator is 135° at the operating center frequency of the second radiator, and the feeding phase of the third radiator with respect to the second radiator is 35° with respect to the second radiator. 1. A receiving antenna device comprising: delaying each of the operating center frequencies of the first, second, and third radiators by 135° and combining the receiving outputs of the first, second, and third radiators.