JPH024162B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a waveguide type non-reflection terminator used in microwave and millimeter waves.

[Prior art]

A waveguide-type non-reflection terminator absorbs electromagnetic waves propagating within a waveguide without reflection, and is often used as a component for three-dimensional circuits.

Figures 1 and 2 show non-reflection terminators conventionally used for rectangular waveguides; the former is a tapered non-reflection terminator 1, and the latter is a multi-stage non-reflection terminator 2.
It is a perspective view showing an example.

These non-reflection terminators are generally manufactured by mechanically processing a block of solid electromagnetic wave absorbing material into the desired shape and dimensions, and there are various shapes. However, although there are various shapes, these non-reflection terminators mainly have a terminator uniform part 3 for absorbing electromagnetic waves and a terminator matching part for impedance matching, as shown in Figures 1 and 2. It basically consists of Section 4.

The tapered non-reflection terminator 1 can obtain relatively broadband electrical characteristics by making the axial length of the terminator matching section 4 approximately one wavelength or more. Further, although the multi-stage non-reflection terminator 2 has a relatively narrow band electrical characteristic, the axial length of the terminator matching section 4 can be shortened to about one quarter of the pipe wavelength at the shortest. The choice between the two is determined by the required conditions, but in either case there are drawbacks as shown below.

First, the shape of the terminator matching portion 4 of the tapered non-reflective terminator 1 is electrically required to have a sharp tip, which has the drawback that processing that satisfies this requirement is difficult. Another drawback was that the tapered tip was easily damaged during handling and storage after processing.

Next, the axial length of the terminator matching part 4 of the multi-stage non-reflection terminator 2 has a large effect on the matching frequency, so it is particularly susceptible to processing errors at frequencies with short wavelengths such as the millimeter wave band. The drawback was that it was difficult to match in the required frequency band.

[Summary of the invention]

The present invention has been made to overcome these drawbacks, and provides a multi-stage non-reflection terminator in which the matching frequency can be easily adjusted by using screws in the terminator matching section.

[Embodiments of the invention]

FIG. 3 is a perspective view showing an embodiment of the present invention, and in the figure, 5 is a screw, and since the screw 5 and the terminator uniform part 3 are connected by a screw structure, the protrusion of the screw 5 The axial length is easily adjustable. The screw 5 has the same function as the terminator matching part 4.
That is, the material, shape, position, etc. of the screw 5 are determined so that the reflected wave mainly generated at the tip of the screw 5 and the reflected wave generated at the terminator matching part 4 cancel each other out in the frequency band used.

First, the material of the screw 5 can be any metal, dielectric, radio wave absorbing material, or the like. That is, when the screw 5 is made of metal, if the terminator matching section 4 reaches a low frequency range in the operating frequency band, the reflection generated at the tip becomes large and matching becomes impossible. Therefore, in this case, a dielectric or a radio wave absorbing material is used as the material for the screw instead of metal.

Next, regarding the shape of the screw, it is also possible to make the diameter of the screw 5 different as in another embodiment shown in FIG. This is a well-known multi-stage impedance matching method in which the axial length of each portion with a different diameter is approximately one-fourth of the wavelength in the tube, and it has better broadband characteristics than a single-stage one. ing. This screw 5 is a double screw that combines a screw with a small diameter and a screw with a large diameter, and the axis of the screw of each diameter is The lengths can be adjusted independently, making it easy to make optimal adjustments.

Furthermore, the position of the screw 5 is not limited to the center of the waveguide, but may be placed close to one side of the tube wall, taking into consideration the magnitude of reflection from the screw. This is because the electric field distribution of the TE ₁₀ mode wave in the rectangular waveguide in the cross section of the waveguide has a sinusoidal distribution, and generally the reflection from the screw 5 becomes smaller as it gets closer to the tube wall. Show trends. Therefore, the position of the screw can be determined experimentally to reduce the reflection of the non-reflective terminator. When impedance matching is achieved, the uniform portion 3 of the terminator sufficiently absorbs the radio waves, so that the non-reflection terminator according to the present invention has good characteristics similar to the conventional non-reflection terminator. Can be done.

In addition, although the above-mentioned example explained the screw in one stage and two stages, the number of stages is not limited to this. Furthermore, the present invention may be applied to other waveguides such as circular waveguides, elliptical waveguides, and cocoon-shaped waveguides. Further, a screw made of radio wave absorbing material and a screw made of metal may be combined to form a double screw.

〔Effect of the invention〕

As explained above, the present invention has the advantage that by using a screw in the impedance matching section, fluctuations in the center frequency caused by machining errors can be easily corrected by adjusting the axial length of the screw.

[Brief explanation of drawings]

Figures 1 and 2 are perspective views of a conventional tapered non-reflective terminator and a multi-stage non-reflective terminator, respectively;
FIG. 3 is a perspective view of a multi-stage non-reflective terminator showing one embodiment of the invention, and FIG. 4 is a perspective view of a multi-stage non-reflective terminator showing another embodiment of the invention. In the figure, 1 is a tapered non-reflective terminator, 2 is a multi-stage non-reflective terminator, 3 is a terminator uniform part, 4 is a terminator matching part, and 5 is a screw. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a multi-stage non-reflection terminator for a waveguide using a radio wave absorbing material that fills the entire cross section of the waveguide, a screw is inserted at the end of the radio wave absorber about a quarter of the way in the tube axis direction. A non-reflection terminator characterized by one wavelength protruding. 2. The non-reflection terminator according to claim 1, which uses a double screw that is a combination of a plurality of screws with different diameters.