JPS61280105A - Antenna for snowfall countermeasure - Google Patents

Abstract

PURPOSE:To prevent electric characteristic deterioration at snowfall to an antenna element by covering a part of a dipole element from the end of a coil trap to each dipole element at both sides of the coil trap by a dielectric member. CONSTITUTION:The dipole element formed by bending an aluminum tube or the like constitutes a folded dipole and its feeding part 7 is covered by the dielectric member 9. In constituting the dipole, one end 26 of the element 8 connected to the coil trap is inserted to a through hole 25 of the cylindrical dielectric member 9 and one end 26 of the element 8 penetrated through the dielectric member 9 is inserted to a hold part 17 of the feeding part 7 of the dipole. The two elements 8 are assembled in this way and an adhesives is injected to the gap between the through hole 25 of the member 9 and the element 8 as required to complete the dipole 5. Further, the dielectric member 9 is made of a synthetic resin with low dielectric loss such as foamed styrol.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an antenna used in snowy areas,
The present invention relates to a type of antenna using a dipole capable of receiving radio waves in a plurality of frequency bands separated from each other, for example, an antenna for snow damage prevention used as a TV VHF antenna, a TV VHFψUHF antenna, and the like.

[Conventional technology]

In order to receive radio waves in multiple frequency bands that are far apart from each other,
A television VHF antenna using a folded dipole with a coil trap provided in the power feeding section is known. While the low band of VHF is 90-108MHz,
The F high band ranges from 170 to 222 ■b, and the frequency relationship is approximately twice that. By providing the above coil trap, the folded dipole operates as a half wavelength dipole in the VHF low band, and operates as a half wavelength dipole in the VHF high band. Operates as a single wavelength dipole, VHF low band,! This allows good reception across both 4HF high bands. However, with such conventional antennas, if there is snow around the coil trap, the capacitance or resistance is connected isometrically in parallel with the coil due to the snow, and the antenna is a traveling wave type antenna. There is a problem in that unnecessary gain also appears in the axial direction of the dipole (direction perpendicular to the boom) and the gain in the designated direction of the antenna decreases.

[Problem that the invention seeks to solve]

This invention eliminates the above-mentioned conventional problems, even if the antenna is equipped with a dipole or a waveguide provided with a coiled ship in order to receive radio waves in multiple frequency bands separated from each other.
The present invention provides an excellent anti-snow antenna that prevents the electrical characteristics from deteriorating when the antenna element is covered with snow.

[Means for solving problems]

The present invention takes the measures described in the claims, and its effects are as follows.

[Effect]

When there is no snow on the antenna, the dipole is equipped with a coil trap, so radio waves in multiple frequency bands separated from each other can be received well.

On the other hand, even if snow falls on the antenna, the dipole element on the coil trap side does not come into contact with the snow due to the dielectric member, so the antenna operates well as if it were not covered with snow.

〔Example〕

The drawings showing the embodiments of the present application will be described below.

Figure 1 shows a TV VH as an example of an antenna for snow damage prevention.
In the perspective view of the F antenna, 1 indicates the antenna support. 2
07 is the antenna body, which is composed of a boom (shaft) 3 made of synthetic resin such as vinyl chloride, a waveguide section 4, a dipole 5, and a reflection section 6. Reference numeral 07 indicates a feeding section of the dipole 5. 8 shows dipole elements each made by cutting an aluminum tube or the like having an outer diameter of 9.5 sag into lengths of about 1301 mm and bending them. Each dipole element 8 constitutes a folded dipole, and the side of the feed section 7 has a length of 10 to 2
It is covered with a dielectric member 9 at position 0c11.

Note that this dipole 5 will be explained in detail later. Reflector 6
consists of a reflector 10 for the VHF low band and two reflectors 13 for the VHF high band fixed to a column 12 mounted perpendicularly to the pool 3. Waveguide section 4
consists of a composite waveguide 14 and a waveguide 15 for VHF high band. It should be noted that each of the reflectors and waveguides mentioned above are made of materials such as aluminum tubes.

Next, FIG. 2 shows a plan view of the dipole with the lid of the power feeding section open. Reference numeral 16 indicates a power feeding box in the power feeding section 7, which consists of a container-shaped main body 18 with an upper opening, which holds and fixes the element 80 in a holding section 17, and a lid body 19 (a second (see Figure 1), and has a space inside thereof that can house a conversion transformer 20 for a well-known paran, which is exemplified as an electronic circuit component. In the box, two terminal fittings 21 are electrically connected to one end of each element 8 and are shown as power supply terminals, and these are connected to the power supply line attachment part via the transformer 20 as is well known. It is electrically connected to a coaxial cable connection terminal (not shown) provided at 22. 23 indicates a coil trap connecting the other ends of each element 8. The main body 18 and the lid 19 are usually integrally molded using an insulating glass material. 24 is a power supply line attachment part 22
As shown in the figure, the length is approximately 15 cIN as a power supply line.
, a through hole 2 in a dielectric member 9 having a cylindrical shape with an outer diameter of 20 m.
5, one end 26 of the element 8 with an outer diameter of 9.5 m connected to the coil trap is inserted into the element 8, and the one end 26 of the element 8, which has passed through the dielectric member 9, is inserted into the holding part 17 of the power supply part 7 of the dipole. Insert into. Assemble the two elements 8 in this way,
If necessary, an adhesive or the like is injected into the gap between the through hole 25 of the dielectric member 9 and the element 8 to complete the dipole 5. In this case, the dielectric member 9 is made of a synthetic resin with low dielectric loss, such as foamed styrene (foamed styrene resin), foamed polyethylene, or foamed polyurethane.

Next, FIGS. 4 to 6, which are diagrams showing the electrical characteristics of the TV VHF antenna as described above, will be explained. Fig. 4 is an explanatory diagram of the electrical circuit of the dipole section, Fig. 5 is a graph showing the frequency characteristics of the antenna gain, and Fig. 6 is a graph showing the frequency characteristics of the antenna's VSWR (voltage standing wave ratio). . In FIG. 5, one end side of the two elements 8 is connected to the 200 Å force side 27 of the conversion truss 7, and the other end side is connected to the coil trap cover. An output side path of the conversion transformer 20 is connected to a coaxial cable 29 illustrated as a power supply line. 30 indicates the center conductor of the coaxial cable 29, and 31 indicates the outer conductor. Next, 32 and 33 indicate a resistance component and a capacitance component, respectively, which occur when snow accumulates on the dipole 5 when the dielectric member 9 is not provided. It is known that the resistance component 32 is several tens of Ω, and the capacitance component 33 is several pF. In addition, in the snow damage prevention antenna of the present application, since the dielectric member 9 is provided at the ends of the two dipole elements 8 where the coil traps 23 are provided, even if snow falls on the dipoles, the ends of the elements 8 on the coil trap 23 side are There is no direct contact with the snow, so unnecessary resistance components 32 and capacitance components 33 are not generated. As a result, the television VHF antenna according to the present invention exhibits good characteristics in both the VHF low band and the VHF high band even when snow accumulates on the antenna, as shown by the solid lines in FIGS. 5 and 6. For reference, TV V without dielectric member 9 is shown.
The characteristics of the HF antenna during snowfall are shown by broken lines in the figure.

Also, as a result of experiments, the range in which the dielectric member 9 covers the element 8 is approximately 1/20 to 1/10 wavelength (the range of the lowest frequency radio waves of the radio waves intended for reception) from the end on the side of the coil trap 23. Fig. 7 is a perspective view showing an example of a different structure of the dielectric member. The same symbols are shown with the letter e added,
Duplicate explanations will be omitted.

g). End portion 26 of dipole element 8e
Dielectric member element 3 shaped like a bamboo ring cut in half with respect to e
4 are joined together and attached to form a dielectric member 9e. At this time, an adhesive or the like is applied to the groove portion 35 of the dielectric member element 34. This example is useful for protecting existing antennas from snow damage.

FIG. 8 is a perspective view showing a further different example of the structure of the dielectric member, in which two rings 36 made of synthetic resin with low dielectric loss are passed through the end 26 f of the dipole element 8 f, and two plates made of synthetic resin are connected. 37 is attached to the ring with adhesive or the like.

In this way, the dielectric member 9f is constructed.

Next, FIG. 9 is a sectional view showing a further different configuration example of the dielectric member, in which the dielectric member 9g is configured in a cylindrical shape, and a through hole 25g for passing a dipole element is provided at both ends. 38
indicates a space, and due to the existence of the space 38, the dielectric member 9g
This reduces the area that directly touches the dipole element.

In this way, it becomes possible to use a material with a large dielectric loss as the dielectric member 9g.

Next, FIG. 10 is a perspective view showing a different example of the antenna for snow damage prevention. In this example, dielectric members 9h are also provided on both sides of the coil trap 39 of the composite waveguide 14h. Since a dipole equipped with a trap is used, radio waves in multiple frequency bands that are far apart from each other can all be received well.

Moreover, even if such a device is equipped with a coil trap, the dipole elements on both ends of the coil trap are provided with a dielectric material, so the ends of the dipole element on the coil trap side will not come into direct contact with the snow during snowfall. It also has the advantage of preventing deterioration of antenna characteristics during snowy conditions.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a perspective view of a television VHF antenna exemplified as an antenna for snow damage prevention; FIG. 2 is a plan view of a dipole with the lid of the power feeding section open; Figure 3 is an exploded perspective view of the main parts of the dipole, Figure 4
Figure 5 is a graph showing the frequency characteristics of antenna gain, Figure 6 is a graph showing the frequency characteristics of antenna VSWR, and Figure 7 is a diagram showing the structure of the dielectric member. FIG. 8 is a perspective view showing a further different example of the structure of the dielectric member, FIG. 9 is a sectional view showing a further different example of the structure of the dielectric member, and FIG. 1O is an antenna for snow damage prevention. FIG. 2... Antenna body, 3... Boom, 5... Dipole, 7... Power feeding section, 8... Dipole element, 9
...Dielectric member, 23... Coil trap. Patent Applicant: Takao Imae Figure 1, Figure 2, Figure 3, Figure 4, Figure 5]: 1 Figure 6, Figure 7, Figure 9, Figure 1011

Claims (1)

[Claims] An antenna for preventing snow damage, characterized in that the dipole equipped with a coil trap has a part of the dipole element covered from the end of the coil trap with a dielectric material for each of the dipole elements on both sides of the coil trap. .