JPS5945284B2 - antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antenna in which the waveguide, radiator and reflector have an outer layer of carbon fiber reinforced resin.

Conventionally, antennas in which the waveguide, radiator, and reflector are made of rod-shaped or cylindrical metal such as iron or aluminum have been generally used.

However, in the case of outdoor antennas, especially in regions with heavy snowfall, snow adheres to the antenna during snowfall, and eventually the sum of the weight of the snow and the weight of the antenna itself exceeds the limit strength of the antenna support material, and the antenna There are many accidents in which the support material breaks.

In addition, sometimes accidents occur in which the waveguide, radiator, or reflector itself breaks due to the weight of the snow on the boom attachment.

Conventionally, as a countermeasure to this problem, the diameters of the waveguide, radiator, reflector, and antenna support material were increased to increase their strength, but this resulted in an increase in the amount of attachment, resulting in further increase in size and size. This led to a vicious cycle of weight gain.

For an outdoor antenna that is permanently used by being attached to a support material and raised high in the air, it is extremely inappropriate for the antenna to be larger and heavier than necessary.

Another countermeasure is to coat the waveguide, radiator, reflector, and boom with fluorine-containing paint to reduce the coefficient of friction between the waveguide, radiator, reflector, and boom, thereby reducing the coefficient of friction between the waveguide, radiator, reflector, and boom, thereby causing the snow to slide off. It has been taken.

However, with this method, snow adhering to the upper surface of each antenna element wraps around to the lower surface, and it is inevitable that snow will adhere to the entire circumference of each element.

Therefore, as a fundamental countermeasure, a method was devised to melt the snow stuck to the antenna using heat.

Specifically, an attempt was made to melt the snow using an electric heater, but it was obvious that installing an electric heater around an antenna with transmitting and receiving functions would immediately cause problems with the antenna's transmitting and receiving functions, so this was not possible. .

An object of the present invention is to overcome the above-mentioned drawbacks of conventional antennas, have substantially the same transmitting and receiving gains, and also has the function of being able to remove snow that adheres to the antenna during snowfall. The purpose is to provide an antenna.

The antenna of the present invention to achieve this purpose is based on the antenna of the present invention.

A waveguide, a radiator, and a reflector are arranged parallel to each other at intervals, and are attached to a boom orthogonal to the waveguide/radiator and reflector, the antenna comprising: The reflector and the reflector have a rod shape, and at least the outer layer of the rod shape is made of carbon fiber reinforced resin, and the carbon fiber reinforced resin has carbon fibers arranged in the axial direction of the rod shape. It is characterized by:

The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a partially cut away longitudinal sectional view of an antenna element made of cylindrical carbon fiber reinforced resin according to an embodiment of the present invention, and FIG.
The figure is a cross-sectional view thereof.

In the figure, an antenna element 1 is made of a cylindrical carbon fiber-reinforced resin in which carbon fibers 2 are arranged only in the axial direction, and resin 3 is impregnated and hardened.

In the above embodiment, the antenna element has a cylindrical shape, but as will be described later (see the explanation section of FIG. 4), the antenna element may have a cylindrical shape.

Further, it may be prismatic or prismatic.

When the carbon fiber reinforced resin has a cylindrical or prismatic shape, the inside thereof may be filled with another material such as a glass fiber reinforced resin or an organic high modulus reinforced resin to form a columnar shape as a whole.

In short, it is sufficient that at least the rod-shaped portion of the antenna element corresponding to the outer layer is made of carbon fiber reinforced resin.

Regarding the shape of the radiator, it is more preferable to use an annular rod-shaped element as shown in FIG. 1 (see 9 in FIG. 5 later) because the radiation effect is improved.

It is preferable that the carbon fibers are filled in a volume content of 60% or more.

This is because if the volume content is less than 60, the resistance of the antenna element becomes too large, which is not preferable.

Also. It is not preferable that the cross-sectional distribution is extremely unevenly filled, but it is desirable that the filling be substantially uniform.

The carbon fiber-reinforced resin that constitutes at least the outer layer of the rod-shaped antenna element must necessarily have carbon fibers arranged in the axial direction of the rod-shape, but carbon fibers arranged in the direction intersecting the axial direction must be included. May contain fiber.

As the resin, thermosetting resins can be used, and among them, epoxy resins are most desirable.

FIG. 3 is a block diagram of a system for supplying high frequency power to the antenna of the present invention to generate heat for melting snow.

In the figure, a high frequency signal oscillator 4 generates a non-modulated high frequency signal corresponding to the resonant frequency of an antenna 7, the signal is amplified by a power intensifier 5, and high frequency power is supplied to the antenna 7 through a feed line 6. .

In the antenna 7, a high-frequency current flows not only in the radiator of the feeding target element but also in other parasitic elements, that is, the waveguide and the reflector, due to the induction effect, causing the radiator, the waveguide, and the reflector to flow, respectively. Joule heat is generated in the constituent carbon fibers.

This Joule heat is due to the high frequency current, and the high frequency current is generated only in the surface layers of the radiator, waveguide, and reflector due to the skin effect, so high frequency power can be used efficiently. .

FIG. 4 is a graph showing the high frequency characteristics of the resistance (per unit length) of an antenna element according to an embodiment of the present invention.

In the figure, the vertical axis represents the resistance value per unit length of a cylindrical (diameter: 5 myn) carbon fiber-reinforced resin (volume content of carbon fiber: 60%), in which carbon fibers are arranged only in the axial direction, and the horizontal axis represents the resistance value per unit length of the carbon fiber reinforced resin (carbon fiber volume content: 60%) The axis is frequency.

Taking into account the skin effect, the resistance (per unit length) R of a cylindrical conductor with radius r is given by the following equation.

Here, π is pi, ω is the angular frequency, μ is the magnetic permeability of the conductor, and σ is the DC electrical conductivity.

The DC resistivity of the cylindrical element (r=0.25(X), ρ=1/
σ21. IX1I2Ωα,μ=1.26X10-8Hr
1, and ω=2π×30×106 Hz, the resistance R becomes 7.3×10 −2 Ωcrn−”, which agrees well with the measured value.

(See FIG. 4) Therefore, it can be seen that the high frequency resistance of a conductor such as the cylindrical element can be calculated using the above equation taking into account the skin effect.

It can be seen that at high frequencies, since the skin effect occurs, the antenna element can be effective not only in a cylindrical shape but also in a cylindrical shape.

By the way, the heating effect due to Joule heat as mentioned above is
This phenomenon occurs neither in good conductors such as metals nor insulators such as plastics, but only in materials with electrical conductivity between the above two, such as carbon fibers.

Also, 7.3 at 30MHz. Since the high frequency resistance value is approximately X10-2 Ωcr''1, it is smaller than the radiation resistance value and has virtually no effect on normal transmission and reception.

Furthermore, the increase in impedance of the entire antenna by using carbon fiber reinforced resin for the antenna element is only about 100%, and conventionally used matching systems such as baluns can be easily re-matched with just a few adjustments. can be taken.

On the other hand, the material for the antenna element is naturally required to have a small high-frequency resistance value as described above, as well as high mechanical strength and light weight.

The values of the specific elastic modulus and specific strength of the cylindrical carbon fiber reinforced resin used to obtain the graph of FIG. 4 are 8×
108 CIrL and 8×106 crn, both of which are approximately four times thicker than existing antenna element materials, such as aluminum.

That is, in terms of mechanical strength, carbon fiber reinforced resin is superior to existing antenna element materials.

Moreover, it is also excellent in lightness.

Furthermore, the material for the antenna element must also have dimensional stability against temperature and humidity and weather resistance.

The axial linear expansion coefficient of the cylindrical carbon fiber reinforced resin is -IX
IO-"C-", which is extremely low.

Similarly, it is extremely stable against humidity, and deformation due to temperature and humidity is virtually negligible.

With existing metal antenna elements, when exposed outdoors to sunlight, wind, rain, snow, etc., the surface paint peels off and the metal itself tends to rust, causing problems in transmitting and receiving functions, but carbon fiber The reinforced resin does not rust and has excellent weather resistance.

Now, in terms of supplying high-frequency power through the feed line and generating heat using the high-frequency resistance of the antenna element with just the right value, it is not limited to carbon fiber, but also metals with approximately the same resistivity as carbon fiber. Alternatively, a wire made of an alloy such as nichrome could be used.

However, in the metal or alloy, the specific elastic modulus,
It is inferior to carbon fiber in terms of specific strength, density, expansion coefficient, etc., and is therefore unsuitable as a material for antenna elements.

Next, an embodiment of the antenna of the present invention will be shown, and an example of its manufacturing method and performance will be explained.

Example A prepreg made by impregnating carbon fibers arranged parallel to each other at intervals with an epoxy resin was wound into a cylindrical shape so that the direction of the carbon fibers was in the axial direction, and heated and cured to form the material shown in Fig. 1. Cylindrical carbon fiber reinforced resin (diameter 5 m) as shown
An antenna element consisting of m) was obtained.

Separately, the cylindrical carbon fiber-reinforced resins are bonded in a square ring shape, and these cylindrical and square ring-shaped carbon fiber reinforced resins are arranged in parallel and at intervals as shown in FIG. Attach it to a boom and use it on the market.
We manufactured a UHF antenna of the same type and dimensions as the HF antenna (element material is aluminum).

In FIG. 5, 7 is a UHF antenna, 8 is a waveguide, and 9 is a UHF antenna.
is a radiator, 10 is a reflector, and 11 is a boom.

The high frequency resistance of the waveguide, radiator, and reflector was 20 to 30Ω, respectively.

In other words, it is about 1/10 of the radiation resistance, and 1
When 00W of power was supplied, approximately 10W of energy was generated as heat.

If the heat generation is on the order of IOW, it is extremely easy to melt the snow adhering to each of the antenna elements immediately.

Further, the reception gain was 95% of the commercially available UHF aluminum antenna.

In other words, it has been revealed that the antenna of the present invention has substantially the same transmission and reception gain as existing commercially available antennas.

As described above, in the antenna of the present invention, at least the outer layer of the rod-shaped waveguide, reflector, and radiator is made of carbon fiber-reinforced resin, and this carbon fiber-reinforced resin is arranged in the axial direction of the rod-shape. Since each element is made of carbon fiber, each element is lightweight, has extremely high mechanical strength, and has excellent dimensional stability against temperature and humidity and weather resistance.

Moreover, by simply supplying high-frequency power through a commonly used power feeder, an induction effect (thus, high-frequency current flows) not only on the radiator of the power-supplied element but also on other parasitic elements, such as waveguides and reflectors. , generating Joule heat in the carbon fibers of each element.

Due to this heat generation, it is extremely easy to immediately melt snow that adheres to each of the elements during snowfall.

Therefore, according to the additional statement, damage to the antenna element itself,
Alternatively, it is possible to prevent an accident of breaking the antenna support material, and the transmission/reception function failure due to the accident does not occur.

Furthermore, if the carbon fibers in each element are arranged only in the axial direction of each element, the thermal conductivity is low in the direction perpendicular to the axial direction, and the skin effect at high frequencies is low. Therefore, it is possible to prevent the Joule heat from being conducted deep into the inner layers of each element and thermally decomposing the resin of the matrix.

Furthermore, the transmission and reception gain is substantially the same as that of commercially available antennas, and there is no disadvantage to using carbon fiber reinforced resin as the element material.

Therefore, it is possible to use the antenna of the present invention in place of an existing antenna, and it is extremely effective to use the antenna of the present invention, especially in areas with heavy snowfall.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway vertical cross-sectional view of a cylindrical antenna element according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view thereof. FIG. 3 is a block diagram of an embodiment of a system for supplying high frequency power to the antenna of the present invention. FIG. 4 is a graph showing the high frequency characteristics of the resistance of the antenna element according to one embodiment of the present invention. FIG. 5 is a perspective view of a UHF antenna according to an embodiment of the present invention. Code, 1: antenna element, 2: carbon fiber, 3: resin, 4
: High frequency signal oscillator, 5: Power amplifier, 6: Power supply, 7
: antenna, 8: waveguide, 9: radiator, 10: reflector,
11: Boom.

Claims (1)

[Claims] 1. An antenna in which a waveguide, a radiator, and a reflector are arranged parallel to each other at intervals, and are attached to a boom orthogonal to the waveguide, radiator, and reflector,
The waveguide, radiator, and reflector have a rod shape, and at least the outer layer of the rod shape is made of carbon fiber reinforced resin, and the carbon fiber reinforced resin has carbon fibers arranged in the axial direction of the rod shape. An antenna characterized by having: