JPH0377683B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to solve the following problems.

(Industrial Application Field) The present invention relates to a primary radiator of an SHF parabolic antenna, and more particularly to a primary radiator that is equipped with a dustproof body to prevent dust from entering inside.

(Prior art) In the case of this type of SHF parabolic antenna primary radiator, reception is attempted with the primary radiator.
Since the SHF radio waves enter the primary radiator through the dustproof body, the dustproof body causes loss to the SHF radio waves. Therefore, in the past, the dustproof body was formed as thin as possible to reduce the loss. However, such a thin dustproof body has the problem that it is easily damaged when it is pecked by a bird or hit by a foreign object blown by the wind, making it unable to exert its dustproof effect. Furthermore, if the dustproof body is formed thickly to obtain high strength, the transmission loss of radio waves will increase and the strength of the radio waves received by the primary radiator will become weaker. There were problems in that it was necessary to use a device with a large diameter as a primary radiator, or to connect special equipment with low noise characteristics to the primary radiator.

(Problems to be Solved by the Invention) This invention eliminates the above-mentioned conventional problems and provides greater mechanical strength by forming the dustproof body thicker, and even with such a thicker structure, there is less loss of radio waves. The present invention aims to provide a primary radiator for an SHF parabolic antenna that can receive signals.

The configuration of the present invention is as follows.

(Means for Solving the Problems) The present invention takes the measures as described in the claims above, and its effects are as follows.

(Function) SHF radio waves pass through the dustproof body and enter the inside of the primary radiator. In this case, the above-mentioned dustproof body has radio wave transmission loss characteristics that are second to the SHF radio wave transmission loss curve.
Since the thickness is set so that the troughs can be obtained, it can pass through the dustproof body with little loss. Further, the dustproof body having the above-mentioned thickness has high mechanical strength and is not easily damaged even when external force is applied to it.

(Example) Below, drawings showing examples of the present application will be described. In FIG. 1, reference numeral 1 denotes a well-known support column, and 2 a parabolic antenna, which is attached to the column 1 using a mounting body 3. In the above parabolic antenna 2, 4
5 is a reflecting mirror, 5 is a support arm, 6 is a stay, 7 is a converter, and 8 is a primary radiator. In this embodiment, the parabolic antenna 2 is an antenna for receiving radio waves (11.7 to 12.0 GHz) from a broadcasting satellite as SHF radio waves, but this parabolic antenna can be used for other purposes as well. A parabolic antenna for receiving 12 GHz band radio waves from communication satellites, a parabolic antenna for transmitting 14 GHz band radio waves to communication satellites, or other 3
There are parabolic antennas that transmit and receive SHF radio waves in the ~30 GHz band.

Next, in FIG. 2 showing the structure of the tip of the primary radiator 8 in detail, the primary radiator 8 is formed into a cylindrical shape using a material with good conductivity such as copper, aluminum, or brass. There is. 9 indicates the opening for receiving SHF radio waves in the primary radiator. In the internal structure of the primary radiator 8, 10 indicates a circular waveguide section, 11 indicates a horn section, and 12 indicates an open end.
Further, in the outer peripheral part of the primary radiator 8, 13 is a tsuba;
Reference numeral 4 denotes a concave groove formed in an annular shape, in which an annular seal 15 for waterproofing is placed. Next, numeral 17 is a feedome, which is made of a synthetic resin material (polyphenylene oxide, for example).
In this field 17, 18 is a dustproof body that shields the opening 9, and its thickness t is the second valley of the SHF radio wave transmission loss curve in the radio wave transmission loss characteristic of the synthetic resin that is the material for forming the dustproof body. It is formed to a thickness (in this example, 8.2 mm) that provides the desired thickness.
Reference numeral 19 denotes a mounting member that is integrally formed with the dustproof body 18 and includes a cylindrical portion 20 and a flange portion 21. Reference numeral 22 denotes a tightening ring for tightening and fixing the collar portion 21 to the collar 13. Moreover, this tightening ring 22 is made of copper, aluminum,
The primary radiator 8 is made of a highly conductive material such as brass, and operates as a single corrugated horn. Some examples of the thickness of the dustproof body 18 when handling SHF radio waves of 11.7 to 12.0 GHz are polycarbonate (thickness 78 mm), polytetrafluoroethylene (9.6 mm), etc. ), tetrafluoroethylene copolymer (7.8mm), etc.

In the case of the above configuration, since the dustproof body 18 shields the opening 9, the primary radiator 8
Even if dust blown by the wind falls down, the dust is prevented from entering the inside of the primary radiator 8. Moreover, since the flange 21 is in close contact with the batkin 15, even if it rains, the rainwater will be transferred to the primary radiator 8.
Intrusion into the interior of the device is prevented.

In the above usage conditions, the signal arrives from a broadcasting satellite.
The SHF radio waves are reflected by a reflector 4 and focused toward a primary radiator 8. In the primary radiator 8,
The radio waves pass through the dustproof body 18 and enter the inside through the opening 9, and the incoming radio waves are given to the converter 7. As is well known, the converter 7 converts the frequency of the radio wave into a lower frequency signal and sends it to the tuner.

Next, Figure 3 shows the radio wave transmission loss characteristics of polyphenylene oxide used as the material for forming the field 17. The horizontal axis represents the thickness of the material, and the vertical axis represents the transmission loss of SHF radio waves. show.
In this characteristic, the thickness t of the dustproof body 18 in the feed dome 17 corresponds to the transmission loss curves A ₁ to A ₃ of SHF radio waves (A ₁ is 10.95 GHz, Az is 11.3 G
Hz and A ₃ indicate the respective transmission loss curves at 11.7GHz)
The thickness is determined so that the second valley part B of is obtained. Furthermore, the thickness is such that the above transmission loss occurs in the valley part.
The range of values that does not significantly affect the reception of SHF radio waves, that is, the permissible value of transmission loss (e.g.
0.3dB) or less. The thickness at which the transmission loss reaches the bottom is as described above.
It is the dimension obtained by multiplying the half wavelength of the SHF radio wave by the wavelength shortening rate of the synthetic resin that is the material for forming the dustproof body.
The half wavelength of the radio wave mentioned above is half the average of the wavelength in free space and the wavelength within the waveguide section 10.

Next, FIG. 4, which shows another embodiment of the present application, will be described. In this example, the dustproof body 18e is provided with a cylindrical portion 25 on the rear side of its peripheral edge, and the horn portion 1
A space 2 is formed between the opening 12e of 1e and the surface 18a of the dustproof body 18e facing the opening end 12e.
6 is shown. The cylinder part 25
The thickness t1 of the field _17e and the width W of the space 26 are both determined by multiplying one quarter of the free space wavelength of the SHF radio waves handled by the wavelength shortening rate of the material forming the field 17e. In this example, the feedome 17e itself is provided with a tightening ring 27 formed integrally therewith.

By providing the cylindrical portion 25 and the space 26 as described above, the radio wave transmission loss caused by the presence of the dustproof body 18e is reduced to the same level as when no dustproof body is present, and the VSWR is also reduced to the same level as when there is no dustproof body. It will be good as well.

It should be noted that the same reference numerals as those in the previous figure are appended with an alphanumeric letter "e" for parts that are functionally the same or equivalent to those in the previous figure, and redundant explanations are omitted.
(Furthermore, in the following figures, the same concept is applied in order, and the alpha abbreviation f and g are attached in order to omit redundant explanations.) Next, Figs. 5 and 6 show other means of attaching the dustproof body. Figure 5 shows an example in which the dustproof body 18f is press-fitted into the waveguide section 10f, and Figure 6 shows the dustproof body 18f.
This shows an example in which 8 g is press-fitted across the horn part 11g and the waveguide part 10g.

(Effects of the Invention) As described above, in the present invention, the dustproof body 18 is attached to the opening 9 of the primary radiator 8 so as to prevent dust from entering the inside of the primary radiator 8. This has the effect of preventing the primary radiator 8 from deteriorating over time and extending its lifespan.

Moreover, the thickness of the dustproof body 18 is determined based on the radio wave transmission loss characteristics of the synthetic resin that is the material for forming it.
Since the thickness is selected so that the second trough of the SHF radio wave transmission loss curve can be obtained, the thickness is relatively large and has the advantage of high mechanical strength against external forces. This means that even if the dustproof body 18 is pecked by a bird or foreign objects blown by strong winds hit the dustproof body 18, it is extremely unlikely that the dustproof body 18 will be damaged. There is an effect that can be achieved.

Furthermore, even if the dustproof body 18 with a large thickness is attached to the opening 9 of the primary radiator 8 as described above, the thickness is such that the transmission loss is small as described above, so that the SHF radio waves can be protected from dust. It has the advantage of being able to receive data with little loss caused by the body 18, and has the effect of solving the conventional problems as described above.

[Brief explanation of drawings]

The drawings show an embodiment of the present application, and Fig. 1 is a side view of a parabolic antenna, Fig. 2 is a partially cutaway side view of a primary radiator, Fig. 3 is a graph showing an example of radio wave transmission loss characteristics, and Fig. 3 is a graph showing an example of radio wave transmission loss characteristics. FIG. 4 is a partially cutaway view showing another example of the shape of the dustproof body, and FIGS. 5 and 6 are views showing other examples of the means for attaching the dustproof body. 8...Primary radiator, 18...dustproof body.

Claims (1)

[Claims] 1 Has an opening for receiving SHF radio waves, and
In the primary radiator of the SHF parabolic antenna, a synthetic resin dustproof body is attached to the above opening to shield the opening and prevent dust from entering inside. A primary radiator of an SHF parabolic antenna, characterized in that the thickness of the primary radiator of the SHF parabolic antenna is set to such a value that the second trough of the transmission loss curve of SHF radio waves is obtained in the radio wave transmission loss characteristics of the synthetic resin that is the material for forming the radiator.