JPH0373601A - Waveguide antenna - Google Patents

Abstract

PURPOSE:To facilitate manufacturing and to reduce the loss of a line by forming a slot to the inside of a waveguide of a feeder, forming the surface with the combination of two conductive plastic forming bodies, adhering the said forming bodies in the middle of the H plane of the TE10 mode in the waveguide, and splitting the forming body at the E plane. CONSTITUTION:Plastic forming bodies 1, 2 with a slot have the same shape of the slots 3, 4 and conductive layers 5, 6 are formed to the surface of the slots 3, 4 including the inner wall. The said forming bodies 1, 2 are assembled so that the slots 3, 4 are opposite to each other and adhered in the middle of the plane H for a signal. Thus, the discontinuous part of the conductor layer in the adhered part imposes any hindrance on currents 9, 10 flowing to the inner wall of the slots and keeps low loss performance in comparison favorably with that of a metal drawn waveguide. Furthermore, the plastic forming body whose surface is made energized is used, then the complicated shape of the feeder is easily made, which is unable to be attained by a conventional waveguide and the entire weight is remarkably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a power feeding section of a waveguide antenna.

[Conventional technology]

Conventionally, waveguides have been used as antennas for information communication and broadcasting in the high frequency region, especially in fields where high performance characteristics are required. The reason for this is that if a waveguide is used as a line for high-frequency signals, conductor loss is extremely small, and there is no dielectric loss or radiation loss, so an antenna with extremely low loss and high efficiency can be realized.

Figures 3 and 4 show examples of conventional waveguide antennas, in which the signal propagated through the antenna part waveguide 0, which has slots aO for receiving radio waves, is transmitted through the coupling slots ( 121 to the feeding section waveguide (b), and is guided to the converter.In this way, conventional waveguide antennas have multiple antenna section waveguides (one feeding section waveguide). Since they are coupled to the tube Q4, each antenna part waveguide α$ is excited in series by the coupling slot a″!J.

On the other hand, in order to maximize the efficiency of the antenna, it is necessary for each antenna part waveguide 03) to be excited in the same phase and with equal amplitude, but in the conventional method, the pitch of the coupling slot Although it is possible to excite the waves in the same phase by making them equal to the internal wavelength of the waveguide, it is extremely difficult to excite them with equal amplitude.

In other words, when the number of coupling slots is about IO or 20 at most, even if the shape of the coupling slots is designed so that the amplitude is as equal as possible, the energy remaining at the end of the feeding waveguide is However, if the coupling slot is designed to bring the remaining energy as close to zero as possible, it will deviate greatly from the equal amplitude condition. In any case, with this type of system, it is impossible to transmit the signal 100% effectively to the converter, and as a result, the efficiency of the antenna cannot be improved much, even though the line loss is small.

[Problem to be solved by the invention]

The present invention was obtained as a result of various studies in view of the drawbacks of conventional waveguide antennas, and its purpose is to provide a feeding section of a waveguide antenna that is easy to manufacture and has low loss. It is on offer.

[Means to solve the problem]

That is, the present invention is assembled with the basic structure of an antenna section that receives radio waves and a feeding section that guides the radio waves received by the antenna section to a converter, and the antenna section and the feeding section are composed of waveguides. In the antenna, the waveguide of the power feeding section is constituted by a combination of two plastic molded bodies each having a groove formed inside thereof and whose surface including the inner wall of the political situation is made conductive; Katsu 2
The two plastic molded bodies are TE and H modes in the waveguide.
This is a waveguide antenna characterized in that the antennas are bonded together at the center of the plane, and the branches are divided at the E plane.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional view of a portion of the power feeding waveguide according to the present invention as shown in FIG. 2(b). The grooved plastic formations (1) and (2) have their grooves (3) and (4)
) have the same shape, and conductive layers (5) and (6) are formed on the surface including the inner walls of the grooves (3) and (4).

Two plastic molded bodies (1) and (2) are placed in the groove (
The dimensions and shape of the waveguide (7) newly formed by assembling 3) and (4) so as to face each other are designed to be equal to the inner dimensions and shape of the waveguide that are compatible with the frequency range to be used. For example, 8-12.4C
I (WRJ-10 or WRJ-1 in the x band of the z band)
2 or WRJ-140 are waveguides whose characteristics are suitable for this band, so if you were to construct a waveguide for WJR-140, you would need plastic molded body (1),
The shapes of the grooves (3) and (4) in (2) can be processed to have a depth of 7.9 mm and a width of 7.9 mm, and the dimensions of the waveguide after assembly are long. Dimension x short dimension is 15.8 m x 7.9 m
becomes. In addition, since the WRJ-24 waveguide is suitable for the Ku band of 18 to 26.5 GHz, the groove (3)
For the shape of (4), it is sufficient to process the groove to have a depth of 5.35 m and a groove width of 4.3 mm, and the dimensions of the waveguide after assembly are long dimension x short dimension of 10.7 mm x 4 mm. There are 30 items.

In Figure 1, (8) shows the amplitude distribution of the electric field of the signal in the TE10 mode, but in the present invention, the plastic molded bodies (1) and (2) are bonded together at the center of the H side of the signal. is the first requirement. By doing this, the discontinuous part of the conductive layer in the bonded part is controlled by the current (9) flowing through the inner wall of the groove.
) and Q[ll, and can maintain low loss comparable to that of a metal drawn waveguide.

Note that the bonding position does not need to be at the exact center of the H surface, and there is no practical problem even if the bonding position is deviated from the center by about ±0.5 to 1.0 degrees.

In the present invention, the bonding method is not particularly limited, and may include fixing with an adhesive or conductive adhesive, screwing, or fitting the plastic molded bodies (1) and (2) together. When fixing by a method such as fitting, it is generally preferable to do it at a pitch of 1/4 or less of the pipe wavelength at the frequency to be used in order to prevent signal reflection and generation of unnecessary modes. However, when bonding the plastic molded bodies (1) and (2) together, there is no need for the bonded surfaces to be in contact with the conductive layer on the inner wall of the groove, as if they were electrically continuous; It is sufficient that there is good adhesion, and there is no need to be particular about the thread pitch.

The conductivity method in the present invention may be a dry conductivity method such as vacuum evaporation or sputtering, or a wet conductivity method such as electroless plating or electrolytic plating, or a combination thereof. A material with a low resistance value is preferable, and gold, silver, copper, aluminum, etc. are suitable. The thickness of these conductive layers must be greater than the skin thickness at the frequency used. If the thickness of the conductive layer is less than this, the current (9), 0 will penetrate into the inside of the plastic molded body without the conductive layer, causing a large line loss, and should be avoided by all means.

For example, if a copper thin film is formed as a conductive layer and the operating frequency is
For bands, the skin thickness is between 0.6 tt m and 0.
．． 8 am, the thickness of the copper should be greater than this. The thickness of the conductive layer is not particularly limited, as long as it is thick, it does not affect the characteristics at all.

Under the above conditions, there was no problem even if the conductive layers (5) and (6) were formed with a thickness of IO μm to 12 μm.

In addition, the conductive layer is made of plastic molded bodies (1) and (2).
It may be formed not only on the surface of the groove side but also on the entire plastic molded body. Furthermore, in order to prevent changes in the surface condition over time due to moisture and humidity, a thin protective layer may be applied to the surface of the conductive layer. Alternatively, a metal film such as Ni or Or may be formed thinly by a dry or wet method, but in order to maintain low loss properties, it is necessary to form it thinner than the conductive layer. Normally, it is several 100 to several 100 OA, and even if the conductive layer is as thick as 10 μm, it is desirable to keep the thickness to about 1 μm.

The material of the plastic molded body used in the present invention is not particularly limited, and is selected from those with a bottom shape, easy to process, and whose surface can be easily made electrically conductive. In this case, ABS resin, polycarbonate, PPS resin, or alloys thereof are suitable.

As described above, the second requirement of the present invention is to use a plastic molded body whose surface is made conductive.This makes it possible to easily create a complex power feeding part shape that cannot be made with conventional waveguides, and to reduce the overall weight. It is also possible to significantly reduce the weight compared to conventional waveguides. Figure 2(a) shows an example of the groove shape on the plastic molded body (1) constituting the power feeding section and waveguide of the present invention, and Figure a3) shows a groove shape of such a plastic molded body with the grooves facing each other. This is an overall diagram pasted together.

Figure 2 (a) shows a groove (3) with branches formed in a single plastic plate, and the groove shape is designed based on the internal dimensions of the waveguide that are compatible with the frequency band used as described above. The third requirement of the present invention is to make the branches divided on the E plane in this way, and because there is no change in the cutoff frequency or impedance before and after the groove branches, matching becomes extremely easy. It has the design advantage of being easy to use.

In addition to this, since the signal waveform before and after the branching of the groove remains the same, there is also the characteristic advantage that a low-loss feed line can be realized without any unnecessary modes occurring in the pipe, which is different from conventional waveguides. It is possible to easily configure a complex power supply line while maintaining a low loss comparable to that of a conventional power supply.

Examples and comparative examples of the present invention will be described below.

(Example 1) A flat plate of ABS resin with a thickness of 10 m and a length of 530 m has a width of 7
．． 9. Cut a groove with a depth of 7.9mm in a straight line in the length direction of the plate, and cut a φ3.2m large base with a left pitch of 50111 at a position of 5 points from the edge of the groove, and cut a groove along the groove. Open symmetrically on both sides. Next, a copper coating was formed on this flat plate to a thickness of 10 μm by electroless plating.

A waveguide was fabricated by fixing two such flat plates whose surfaces were made conductive with 3M screws using a φ3.2m hole so that the grooves faced each other. 11.7~ of this waveguide
When the characteristics at 12.0 GHz were measured, the line loss was 0.20 dB.

(Example 2) A groove with a depth of 7.9 tm was machined in the following order on an ABS resin flat plate with a length of 436 m+* and a width of 324 m.

■ Width 7mm from the center of one of the short sides of the ABS resin flat plate.
9mm, length 10.6mm? Cut.

■ Cut the groove so that it branches at an angle of ±20° with respect to the length direction of the flat plate.The length of the branched groove is 20Ln, and the width is tapered to widen from 3.95gai to 7.9m. .

■ Cut the flat plate lengthwise to a width of 7.9 m and a length of io, 6 m.

■ Cut grooves so that they diverge at an angle of ±17° to the length direction of the flat plate. The length of the branched groove is 116mm,
The width tapers from 3.95 m to 7.9 as.

■ Width 7.9 s and length 10.6 s in the length direction of the flat plate.

Cut with.

■ Cut grooves so that they diverge at an angle of ±10@ to the length direction of the flat plate. The length of the branch is 95m and the width is 3.
Taper so that it spreads from 95 kaku to 7.9 tm.

■ Width 7.9 mm in length direction of flat plate, length 10.6 rm
Cut with.

In this way, a total of eight grooves were gradually combined into a single groove as shown in FIG. 2(a).

Next, at a pitch of 50 m at a position 10 mm from the edge of the groove, φ
A 3.2 m hole was drilled along the groove. Then, in the same manner as in Example 1, a copper coating having a thickness of LOum was formed by electroless plating.

A waveguide was obtained by fixing such processed 1ff+2 sheets with 3 mm screws using a φ3.2 m hole so that the grooves faced each other. 11.7 to 1 of this feed waveguide
When we measured the characteristics at 2.0GHz, the reflection was -2.
The insertion loss was less than 0 dB, the insertion loss was less than 0.5 dB, and the distribution ratio of the eight waveguides was within ±0.5 dB.

(Comparative Example 1) The same waveguide dimensions as in Example 1 (7.9 mm x 15 mm).
■ When we measured the characteristics at 1.7 to 12.0 GHz of a red copper WRJ-140 drawn waveguide cut into 530 pieces of the same length as in Example 1, we found that the line The loss was 0.18 dB.

(Comparative Example 2) As a method of laminating two flat plates, a conductive adhesive having a volume resistivity of 5 x 10-'Ω- after curing was applied to the edges of the grooves without any gaps, and then laminated at 50°C. 11 for the same waveguide as in Example 1 except that it was cured and bonded for 2 hours.
．． When the characteristics at 7 to 12.0 GHz were measured, the line loss was 0.20 dB.

(Comparative Example 3) The waveguide was the same as Example 1 except that the groove width was 15.8 m, the depth was 3.95 wa, and the bonding position of the two plastic plates was at the center of the 8th surface. ~12.0
When we measured the characteristics at GHz, the line loss was 1.
It was 1 dB.

〔Effect of the invention〕

As is clear from the above, according to the present invention, it is not only possible to easily fabricate a power feed section with a complex shape, which was extremely difficult with conventional metal waveguides, but also to realize a lightweight and low-loss power feed line. For example, if applied to the power feeding part of a satellite broadcast receiving antenna, a planar antenna with excellent efficiency can be obtained due to its low loss property.

[Brief explanation of drawings]

FIGS. 1 and 2 are feed waveguide recovery according to the present invention. Further, FIGS. 3 and 4 are diagrams showing an example of a conventional waveguide antenna.

Claims (1)

[Claims] (1) The antenna is assembled with the basic structure of an antenna section that receives radio waves and a feeding section that guides the radio waves received by the antenna section to a converter, and the antenna section and the feeding section are constructed of waveguides. The waveguide of the power feeding section is constituted by a combination of two plastic molded bodies each having a groove formed inside thereof and whose surface including the inner wall of the groove is made conductive; A waveguide antenna characterized in that two plastic molded bodies are bonded together at the center of the H plane of the TE_1_0 mode in the waveguide, and the branch is divided at the E plane.