JP2000081457A - Electric wave absorber measuring jig and measuring method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the easiness of sample loading and measuring accuracy. SOLUTION: This measuring jig comprises: an outer conductor 12, having a cross section in the form of a rectangle that is 400 mm×600 mm and having a cylindrical part 12b taking the form of a rectangle that is also 400 mm×600 mm and integrated with the open end of a hone-antenna-shaped part 12a gradually spreading from a coaxial connector 16 while keeping that ratio as does a hone antenna; a short-circuit board 14 in which a metallic thin inner conductor 13 electrically insulated from the outer conductor 12 is placed in a position dividing the insides of both the hone-antenna-shaped part 12a and the cylindrical part 12b of the outer conductor 12 into two equal parts, and which causes an electric short circuit on the end faces of the outer conductor 12 and the inner conductor 13 in order to load and evaluate a sample; a closing door 15 equipped with a spring mechanism, for installing and removing the sample and for completing contact with the outer conductor 12; and an N-type coaxial connector 16 for applying a TEM wave between the outer conductor 12 and the inner conductor 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a horn antenna having an outer conductor having an end face dimension of 400 mm.times.600 mm and a cylindrical portion having the same end face shape, and a short side inside the outer conductor having an end face width of 400 mm. A structure in which a thin plate-shaped inner conductor is divided into two equal parts, and each end face is short-circuited by a metal short-circuit plate.
Again edge shapes with ² integrated similar cylindrical portion, the inner conductor is also an outer conductor and an end surface dimensions and a 100 mm ² in similar shape, square each of the end face portion is short-circuited by the metallic short circuit plate of coaxial structure In addition, the ratio of the horn antenna-like portion or pyramid-like portion of the outer conductor and the inner conductor to the cylindrical portion is from 8: 2 to 9: 1. For a radio wave absorber measurement jig with a structure with an open / close door that has a contact surface with an external conductor that performs the function of attaching and detaching the measurement sample to either of the cylindrical parts, and the lower limit frequency of the return loss characteristic in the frequency domain The present invention relates to a method for measuring a radio wave absorber that variably adjusts a width of a gate time process in a time domain so that a constant value is obtained.

[0002]

2. Description of the Related Art Conventional radio wave absorber measurement jigs include a measurement jig utilizing a coaxial tube and a measurement jig in which a flat strip conductor is provided in parallel with one surface of an external conductor having a rectangular cross section. Or a horn-shaped main body having a square cross section, and a partition plate for dividing an inner conductor into two equal parts over both the main body part and the cylindrical part by providing an external conductor having a square cylindrical part. Measuring jig (Japanese Unexamined Patent Publication
285907).

In the measurement of a radio wave absorber, there is a method of correcting a return loss characteristic in a frequency domain by a gate time processing method in a time domain.

However, in these measurement jigs, when the radio wave absorber as the sample is attached or detached, the external conductor and the internal conductor located on the opposite surface of the connector portion to which a high frequency signal from the network analyzer as the measuring device is applied are short-circuited. The short-circuit plate was once separated from the outer conductor and the inner conductor, and after mounting the sample on the surface of the short-circuit plate, the outer conductor and the inner conductor were short-circuited again before measurement. However, moving the short-circuiting plate in the high-frequency measurement has a slight change in contact resistance affecting the measurement, and it is somewhat difficult to attach and detach the sample using the short-circuiting plate-movable measurement jig.

[0005] Further, the conventional gate time processing method in the time domain is excellent in that a complicated reflected wave newly generated inside the jig can be suppressed by loading a radio wave absorber as a sample on the short-circuit plate surface of the jig. Has an effect. However, when the reflection attenuation characteristic is shifted to the frequency domain and corrected, a large error occurs particularly in the attenuation characteristic at the lower limit frequency.

[0006]

SUMMARY OF THE INVENTION In the present invention, the disadvantages of the conventional measuring jig are the elimination of the measurement error due to the movement of the short-circuit plate for loading the sample, the difficulty in attaching and detaching the sample, and the correction error in the gate time processing method. The purpose is to provide a measuring jig and a measuring method for accurately capturing the absorption characteristics of the radio wave absorber.

[0007]

In order to achieve the above object, the cross-sectional dimension of the radio wave absorber measuring jig according to the present invention is determined based on a sample size of 100 mm × 100 mm. The height of the jig was determined from the viewpoint of measurement accuracy.

[0008] The cross-sectional dimension of a horn antenna-like spread at an angle of about 15 degrees from the coaxial connector is 400.
An external conductor held in such a manner that it does not come into contact with the external conductor at a position where the inside of the external conductor is divided into two equal parts in the short side direction in which a cylindrical part having the same cross-sectional shape is integrated with the rectangular opening end surface of mm × 600 mm. A thin plate-shaped inner conductor with a 400 mm end face width similar to that of the above is provided, and a rectangular end face of the outer conductor and a flat end face of the inner conductor are short-circuited by a metal short-circuit plate, so that 24 samples can be loaded. Jig and

The inside of the outer conductor, in which a cylindrical portion having the same cross-sectional shape is integrated with the opening end face of a square having a cross-sectional size of 300 mm ² and having a pyramid shape extending at an angle of about 15 degrees from the coaxial connector, is referred to as an external conductor. Is similar to the outer conductor held at the same position where it does not touch and has a cross-sectional dimension of 100
The inner conductor of mm ² provided, which is also jig square end face can loaded with eight samples structure shorted by metallic short circuit plate of the outer conductor of the square end face and the inner conductor.

The height of these measuring jigs is 10
However, in consideration of the suppression of the reflected wave by the gate processing method in the time domain, the ratio of the horn antenna part and the cylindrical part or the pyramid part and the cylindrical part of the measurement jig is set to 8:
Selected from 2 to 9: 1.

Further, a means is provided for attaching an opening / closing door having a spring-like contact surface capable of obtaining reliable contact with the outer conductor at an appropriate position of the outer conductor of the measuring jig.

In the measurement of the radio wave absorption characteristic, a means for variably adjusting the width of the gate time processing in the time domain so that the lower limit frequency of the return loss characteristic in the frequency domain becomes a constant value has been newly developed. The gate time variable adjustment method became possible as a result of selecting the ratio of the horn antenna-like or pyramid-like portion to the cylindrical portion of the measurement jig within the range of 8: 2 to 9: 1.

[0013]

The electromagnetic wave absorber, which is a sample, is loaded on the short-circuit plate via the detachable opening / closing door attached to the outer conductor of the measuring jig, and a TEM electromagnetic field is applied between the outer conductor and the inner conductor. When a network analyzer is connected to the coaxial connector of the above via a coaxial cable, the reflected wave from the sample can be captured, and the absorption characteristics of the radio wave absorber with respect to frequency can be evaluated.

At this time, the ratio of the horn antenna-shaped or pyramid-shaped portion to the cylindrical portion of the measuring jig is changed from 8: 2 to 9:
When it is selected within the range of 1, the influence of the reflected wave inside the measuring jig can be reduced by loading the sample on the measuring jig. As a result, the width of the gate time processing can be changed, the radio wave absorption characteristics with the effect of the reflected wave from the sample suppressed can be obtained, and the measurement can be performed with higher reproducibility and higher accuracy than the conventional method. .

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. This embodiment is only two examples that embody the present invention, and does not limit the technical scope of the present invention. 1 and 2 show a horn antenna type radio wave absorber measuring jig 1 used in a first embodiment of the present invention.
1 shows the structure of FIG. The horn antenna type radio wave absorber measuring jig 11 is a rectangle having a cross section of 400 mm × 600 mm, and the horn antenna-like portion 12 which spreads from the coaxial connector 16 while maintaining this ratio gradually like the horn antenna.
a external conductor 12 having a rectangular cylindrical portion 12b of 400 mm × 600 mm integrated with the open end of the outer conductor 12, a horn attenuator-like portion 12a and a cylindrical portion 1
2b, a thin inner conductor 1 made of metal that is electrically insulated from the outer conductor 12
In order to dispose the sample 3 and load and evaluate the sample, a short-circuit plate 14 for electrically short-circuiting the end surfaces of the outer conductor 12 and the inner conductor 13, and to attach and detach the sample to complete the contact with the outer conductor 12. The opening and closing door 15 with a spring mechanism, and N for applying a TEM wave between the outer conductor 12 and the inner conductor 13
Type coaxial connector 16.

Horn antenna type radio wave absorber measurement jig 1
In order to measure the radio wave absorption characteristics of the sample 7 using the sample 1, the sample 7 is short-circuited without being loaded, the two doors 15 are securely fastened so as to contact the outer conductor 11, and the coaxial connector 16 is connected.
Is connected to a network analyzer as a measuring instrument. The network analyzer short-circuit-calibrates the completely reflected wave from the short-circuit plate 14. At this time, if the ratio of the horn antenna-like portion 12a and the cylindrical shape portion 12b of the outer conductor 11 is selected in the range of 8: 2 to 9: 1, the reflection in the radio wave absorber measurement jig 11, which is similar to the metal box, is obtained. Produces fewer advantages. Then, as shown in FIG.
Load on top. This loading state is as shown in FIG. 2B, and the 24 samples 7 are arranged on the short-circuit plate 14 via the two opening / closing doors 15 without any gap. At this time, the inner conductor 13
By setting the dimension in the long side direction to 400 mm, a gap of 100 mm was opened from each of the external conductors 11, and the effect of reducing the gap between the samples 7 was exhibited.

FIGS. 3 and 4 show the structure of a square wave absorber measuring jig 21 used in the second embodiment of the present invention. Square wave absorber measuring jig 21 has a cross section of 300 mm x
An external conductor 22 having a square shape of 300 mm and also having a square cylindrical portion 22 b of 300 mm × 300 mm integrated with the open end of the pyramid-shaped portion 22 a, a pyramid-shaped portion 22 a of the external conductor 22 and a square cylindrical portion 22 b Over both,
The inner conductor 23 is electrically insulated from the outer conductor 22, has a shape similar to that of the outer conductor 22, and has an end surface of 100 mm × 100 mm at the same position as the outer conductor 22. A short-circuit plate 24 electrically short-circuited at the end faces of the inner conductor 22 and the inner conductor 23;
An opening / closing door 25 having a spring mechanism for making complete contact with the N-type coaxial connector 26 for applying a TEM wave between the outer conductor 22 and the inner conductor 23.

In order to measure the radio wave absorption characteristics of the sample 7 using the square radio wave absorber measurement jig 21, the sample 7 is not loaded and a short circuit state is set, and the two doors 25 are securely contacted with the external conductor 22. Then, a network analyzer as a measuring instrument is connected to the coaxial connector 26. The network analyzer short-circuit-calibrates the completely reflected wave from the short-circuit plate 24. At this time, if the ratio between the pyramid-shaped portion 22a and the cylindrical portion 22b of the outer conductor 21 is selected in the range of 8: 2 to 9: 1, the reflection in the radio wave absorber measuring jig 21 which is similar to the metal box is small. Produce benefits. Then, the sample 7 of 100 mm square is loaded on the short-circuit plate 24 as shown in FIG. This loading state is as shown in FIG. 4B, and eight samples 7 are arranged on the short-circuit plate 24 via the two doors 25 without any gap.

In the case of the first embodiment, in the case of the first embodiment, the return loss characteristics are shown in FIG. 5 with the 24 samples 7 arranged and loaded on the short-circuit surface 14 without any gap. The region and the time region of FIG. 5B are measured simultaneously.

In the measurement, the lower limit frequency f _L in a state where the gate time processing is not performed is −20 in the frequency domain of FIG.
Gate processing after setting to dB. Then, the processing shifts to the time domain of FIG. 5B, and the gate time width is variably adjusted, so that the gate time width is varied so that f _L coincides with the level of −20 dB in the frequency domain of FIG. 5A. . Measurement is f _L
Is completed when the value is equal to -20 dB.

By the variable gate time processing method, the influence of the reflected wave inside the radio wave absorber measurement jig 11 or 21 can be substantially suppressed, and only the radio wave absorption characteristic of the sample 7 can be evaluated with high reproducibility and high accuracy.

[0022]

The radio wave absorber measuring jig 11 according to the present invention.
Alternatively, 21 and its measurement method employ the above-described structure for easily attaching and detaching the sample and the method of suppressing reflected waves, thereby making it easy to attach and detach the radio wave absorber and suppressing reflected waves inside the measurement jig. did it. Therefore, the radio wave absorption characteristics of the sample 7 can be measured with high accuracy and good reproducibility.

Further, by selecting the ratio of 12a and 12b and the ratio of 22a and 22b of the radio wave absorber measuring jig 11 or 21 in the range of 8: 2 to 9: 1, a variable gate time processing method becomes possible. The effect that the radio wave absorption characteristics of the sample 7 can be measured with high accuracy has been produced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a horn antenna type radio wave absorber measuring jig according to a first embodiment of the present invention.

2A is a longitudinal sectional view of a horn antenna type radio wave absorber measuring jig, and FIG. 2B is a transverse sectional view thereof.

FIG. 3 is a perspective view of a square wave absorber measuring jig according to a second embodiment of the present invention.

FIG. 4A is a longitudinal sectional view of a rectangular wave absorber measuring jig, and FIG. 4B is a transverse sectional view thereof.

FIG. 5 shows a measurement method using a variable gate processing time method.
(A) is a return loss characteristic in a frequency domain, and (B) is a reflection voltage characteristic in a time domain.

[Explanation of symbols]

 11 ‥‥‥‥‥‥ Horn antenna type radio wave absorber measurement jig 21 ‥‥‥‥‥‥ Square radio wave absorber measurement jig 12, 22 ‥‥‥ Outer conductor 12 a ‥‥‥‥‥ Horn antenna-like portion 22 a ‥‥‥ {Pyramidal part 12b, 22b} Cylindrical part 13, 23} Inner conductor 14, 24} Short circuit board 15, 25} Opening door 16, 26} Coaxial connector

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yasuo Mogi 4-4-1-1, Asama-cho, Fuchu-shi, Tokyo Inside Kyoritsu Electronics Industry Co., Ltd.

Claims (5)

[Claims] The dimensions of a short side and a long side of a cross section of a horn antenna-shaped spread from a coaxial connector are each 40.
An outer conductor in which a tubular portion having a sectional shape equivalent to that of the opening portion of the rectangular portion of 0 mm and 600 mm is integrated, a horn antenna-shaped portion of the outer conductor, and a tubular portion having a rectangular cross section. It is similar to the plane shape of the long side surface of the outer conductor at a position where the short side inside the outer conductor is divided into two equal parts, and is held so as not to contact with the outer conductor, and has the same width as the cylindrical long side surface of 400 mm. A thin inner conductor of
A radio wave absorber measurement jig characterized by a structure in which an end portion of a rectangular cross section of the outer conductor and an end surface portion of a thin plate cross section of the inner conductor are short-circuited by a metal short-circuit plate. 2. An external conductor in which a cylindrical portion having a cross-sectional shape similar to that of a square portion having a cross-sectional size of 300 mm ² and having a pyramidal shape extending from the coaxial connector is integrated, and a pyramidal shape of the external conductor. The inner conductor having a shape similar to that of the cylindrical portion and the cylindrical portion and having a cylindrical shape of 100 mm ² , and a square cross-sectional end surface portion of the external conductor and a square cross-sectional end surface portion of the internal conductor also short-circuited by a metal short-circuit plate. A radio wave absorber measurement jig that features a rectangular coaxial structure. 3. The ratio of the horn antenna-shaped portion and the cylindrical portion of the outer conductor and the inner conductor of claim 1 or the pyramid-shaped portion and the cylindrical portion of the outer conductor and the inner conductor of claim 2 is 8: 2.
A radio wave absorber measurement jig characterized by a structure ranging from 1 to 9: 1. 4. An open / close door having a contact surface with an external conductor, which functions to attach and detach a measurement sample, to one of a horn antenna-shaped portion, a pyramid-shaped portion, and a cylindrical portion of the external conductor according to claim 1 or 2. A radio wave absorber measurement jig that features a mounting structure. 5. A measurement of a radio wave absorber characterized by variably adjusting a width of a gate time processing in a time domain so that a lower limit frequency of a reflection attenuation characteristic in a frequency domain showing a radio wave absorption characteristic becomes a constant value. Law.