JP2012112806A - Anechoic chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anechoic chamber capable of suppressing deterioration of a measuring accuracy by suppressing overlapping of an arrival time of unnecessary scattered wave with a time response of reflection wave from whole measuring object and removing the scattered wave from a gating in a time domain.SOLUTION: An anechoic chamber (10) applies an electric wave emitted from a transmission antenna (1) to a measuring object (3), receives the reflection wave reflected by the measuring object by a receiving antenna (2) and calculates a radar cross section from the intensity of the reflected waves. This anechoic chamber includes a wall surface that covers the measuring object, a transmission antenna, and the receiving antenna. The wall surface comprises; a tapered wall surface (12) configured to have an inclination, adjacent to the transmission antenna and the receiving antenna; and a cylindrical wall face (13) configured to have a cylindrical shape, at the periphery of the measuring object.

Description

  The present invention relates to an anechoic chamber for measuring a cross-sectional area of a radar, and relates to an anechoic chamber in which deterioration of measurement accuracy due to unnecessary scattered waves is suppressed.

  As an index indicating the reflection intensity of a target such as a flying object, a radar cross section (RCS: Radar Cross Section) is generally used. In order to accurately grasp the radar cross section of the target, the radar cross section is measured in an anechoic chamber or the like (see, for example, Non-Patent Document 1). Therefore, an outline of a conventional RCS measurement method using an anechoic chamber will be described by taking the configuration of the anechoic chamber described in Non-Patent Document 1 as an example.

  FIG. 6 is an explanatory diagram of a method for measuring the radar cross-sectional area of an object to be measured in a conventional anechoic chamber described on page 257 of Non-Patent Document 1. In FIG. 6, the anechoic chamber 10 has a substantially rectangular shape and includes a radio wave absorber 11 on the surface. In the anechoic chamber 10, a transmitting antenna 1, a receiving antenna 2, and a device under test 3 are arranged. A measurement area 4 is shown around the object to be measured 3.

  The radio wave radiated from the transmitting antenna 1 is irradiated to the device under test 3, and the reflected wave 21 reflected by the device under test 3 is received by the receiving antenna 2. The radar cross section can be calculated from the intensity of the reflected wave 21 of the object to be measured 3. This measurement method is well practiced conventionally, and can measure the radar cross-sectional area of the DUT 3. However, as shown in FIG. 6, the reception antenna 2 simultaneously receives the reflected wave 21 and the unwanted scattered wave 22 from the wall surface.

  Next, FIG. 7 is an explanatory diagram of a method for measuring the radar cross-sectional area of the object to be measured in the conventional anechoic chamber described on page 266 of Non-Patent Document 1. What is the anechoic chamber in FIG. It has a different dark room shape. In FIG. 7, the same elements as those in FIG. 6 are given the same reference numerals.

  As in the case of FIG. 6 above, the radio wave radiated from the transmitting antenna 1 is applied to the device under test 3, and the reflected wave 21 reflected by the device under test 3 is received by the receiving antenna 2. The radar cross section is calculated from the intensity of. In the anechoic chamber shown in FIG. 7, a tapered wall surface portion 12 having an inclined wall surface in the dark room is provided in the vicinity of the transmitting antenna 1 and the receiving antenna 2 to reduce unnecessary scattered waves from the wall surface. However, as shown in FIG. 7, unnecessary scattered waves 22 a and 22 b are still received by the receiving antenna 2.

  FIG. 8 is an explanatory view showing the measurement result of the reflected wave from the measurement object using the conventional anechoic chamber as shown in FIGS. Specifically, the time responses of the direct reflected wave 21 from the DUT 3 and the unnecessary scattered wave 22 due to the wall surface or the like are shown. As shown in FIG. 8, the reflected wave component of the object to be measured 3 (the component of the reflected wave 21) has a temporal spread. In the measurement of the radar cross-sectional area, unnecessary waves outside the time response range related to the reflected wave 21 from the object to be measured 3 can be removed by hardware gating or software gating.

Eugene F.M. By Knott, Scitech Publishing, Radar Cross Section Measurement, p. 257, p. 266

However, the prior art has the following problems.
As shown in FIG. 8, the unnecessary wave included in the time response of the reflected wave 21 of the DUT 3 cannot be removed even by hardware gating or software gating, and the measurement accuracy deteriorates. cause. In particular, in the measurement in the anechoic chamber 10 having the tapered wall surface portion 12 as shown in FIG. Cause degradation of measurement accuracy.

  Here, unnecessary scattered waves include unnecessary scattered waves that reach the receiving antenna 2 when the radio waves radiated from the transmitting antenna 1 are reflected on the wall surface, and radio waves radiated from the transmitting antenna 1 are reflected on the wall surface, An unnecessary scattered wave that reaches the receiving antenna 2 by being scattered by the measurement object 3 or a component that reaches the receiving antenna 2 after being reflected by the measurement object 3 after being scattered by the measurement object 3 and reflected from the wall surface Unnecessary scattered waves can be considered.

  In the conventional measurement of the radar cross section in the anechoic chamber, the arrival time of these unnecessary scattered waves overlaps the time response of the reflected wave 21 from the entire object to be measured. For this reason, there was a problem that unnecessary scattered waves could not be removed by gating in the time domain, resulting in deterioration in measurement accuracy.

  The present invention has been made to solve the above-described problems, and suppresses the arrival time of unnecessary scattered waves from overlapping the time response of reflected waves from the entire object to be measured. An object of the present invention is to obtain an anechoic chamber that can suppress degradation of measurement accuracy by removing scattered waves by gating.

  The anechoic chamber according to the present invention irradiates the object to be measured with the radio wave radiated from the transmitting antenna, receives the reflected wave reflected by the object to be measured by the receiving antenna, and calculates the radar cross section from the intensity of the reflected wave. Therefore, in an anechoic chamber provided with walls to cover the object to be measured, the transmitting antenna, and the receiving antenna, the wall surface is provided with a tapered wall surface provided to have an inclination in the vicinity of the transmitting antenna and the receiving antenna, and the object to be measured. And a cylindrical wall surface portion provided so as to have a cylindrical shape.

  According to the anechoic chamber of the present invention, the presence of unnecessary scattered waves is reduced, the propagation time of unnecessary scattered waves is lengthened, and unnecessary scattered waves overlap with the time response of reflected waves from the entire object to be measured. In order to prevent the arrival time of unnecessary scattered waves from overlapping the time response of the reflected wave from the entire object to be measured, the wall surface structure around the object to be measured is made cylindrical. By removing the scattered wave by gating, it is possible to obtain an anechoic chamber in which deterioration of measurement accuracy can be suppressed.

It is the figure which showed the shape of the anechoic chamber by Embodiment 1 of this invention. It is explanatory drawing which showed the measurement result of the reflected wave from the to-be-measured object using the anechoic chamber in Embodiment 1 of this invention. It is the top view and side view which showed the shape of the anechoic chamber by Embodiment 1 of this invention. It is the figure which showed the shape of the anechoic chamber by Embodiment 2 of this invention. It is the figure which showed the shape of the anechoic chamber by Embodiment 3 of this invention. It is explanatory drawing of the method of measuring the radar cross section of the to-be-measured object in the conventional anechoic chamber described in page 257 of the nonpatent literature 1. It is explanatory drawing of the method of measuring the radar cross-sectional area of the to-be-measured object described in the non-patent literature 1 page 266 in the conventional anechoic chamber. It is explanatory drawing which showed the measurement result of the reflected wave from the to-be-measured object using the conventional anechoic chamber like FIG. 6, FIG.

  Hereinafter, preferred embodiments of the anechoic chamber of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same element as the past.

Embodiment 1 FIG.
FIG. 1 is a diagram showing the shape of an anechoic chamber according to Embodiment 1 of the present invention. In FIG. 1, the anechoic chamber 10 includes a radio wave absorber 11 on the surface, a tapered wall surface portion 12, and a cylindrical wall surface portion 13. In the anechoic chamber 10, a transmitting antenna 1, a receiving antenna 2, and a device under test 3 are arranged. A measurement area 4 is shown around the object to be measured 3.

  The tapered wall surface portion 12 is a wall surface portion having a tapered shape provided in the vicinity of the transmission antenna 1 and the reception antenna 2 so as to have an inclination. Further, the cylindrical wall surface portion 13 is a wall surface portion provided so as to have a cylindrical shape around the object to be measured 3. As shown in FIG. 1, the present invention has a technical feature in that a tapered wall surface portion 12 is provided in the vicinity of the transmitting antenna 1 and the receiving antenna 2 and a cylindrical wall surface portion 13 is provided around the device under test 3. Yes.

  Next, a method for measuring the radar cross section using the anechoic chamber shown in FIG. 1 in the first embodiment will be described. The radio wave radiated from the transmitting antenna 1 is irradiated to the device under test 3, and the reflected wave 21 reflected by the device under test 3 is received by the receiving antenna 2. The radar cross-sectional area can be calculated from the intensity of the reflected wave 21 of the device under test 3.

  Here, the taper wall surface portion 12 provided in the dark room wall surface is set with a taper inclination angle so that the reflected wave from the taper portion does not directly irradiate the DUT 3. In the anechoic chamber 10 according to the first embodiment, the radio wave radiated from the transmitting antenna 1 is reflected by the cylindrical wall surface portion 13 and received by the receiving antenna 2 by the action of the cylindrical wall surface portion 13 having a cylindrical shape. The component can be greatly reduced compared to a conventional anechoic chamber.

  The radio wave radiated from the transmitting antenna 1 and incident on the cylindrical wall surface 13 is received by the receiving antenna 2 as a reflected wave 21 or an unwanted scattered wave 22 that is directly received after being reflected by the device under test 3. One path of the unnecessary scattered wave 22 is shown in FIG. Due to the effect of the cylindrical wall surface 13 having a cylindrical shape, the unnecessary scattered wave 22 is reflected by the dark room wall surface and the DUT 3 and easily reaches the receiving antenna 2 and has a long propagation distance. is doing.

  FIG. 2 is an explanatory diagram showing the measurement result of the reflected wave from the object to be measured using the anechoic chamber according to Embodiment 1 of the present invention. Specifically, the time responses of the direct reflected wave 21 from the DUT 3 and the unnecessary scattered wave 22 due to the wall surface or the like are shown. As shown in FIG. 2, since the propagation path length of the unnecessary scattered wave 22 can be increased, the unnecessary wave (unnecessary scattered wave) reaches outside the range of the time response of the reflected wave 21 of the object 3 to be measured. Can do. Such an unnecessary wave can be removed by hardware gating or software gating, and only a desired reflected wave 21 from the device under test 3 can be extracted.

  FIG. 3 is a top view and a side view showing the shape of the anechoic chamber according to Embodiment 1 of the present invention. The top view is the same as FIG. The taper wall surface portion 12 shown in FIG. 3 exemplifies a case where the taper wall portion 12 is tapered not only in the horizontal plane but also in the vertical direction. However, the taper structure only in the horizontal plane has a certain effect, and the tapered wall surface portion 12 can be a taper structure only in the horizontal plane.

  As described above, according to the first embodiment, the presence of unnecessary scattered waves is reduced, the propagation time of unnecessary scattered waves is lengthened, and unnecessary scattering is performed with respect to the time response of reflected waves from the entire object to be measured. A structure in which the wall surface structure around the object to be measured is cylindrical is provided so that the waves do not overlap. As a result, it is possible to suppress the arrival time of unnecessary scattered waves from overlapping with the time response of reflected waves from the entire object to be measured, and it is possible to remove scattered waves by gating in the time domain, resulting in deterioration in measurement accuracy. It is possible to realize an anechoic chamber that can suppress noise.

Embodiment 2. FIG.
In the second embodiment, an anechoic chamber having a tapered wall surface shape different from that of the first embodiment will be described.

  FIG. 4 is a diagram showing the shape of an anechoic chamber according to Embodiment 2 of the present invention. In FIG. 4, the anechoic chamber 10 includes a radio wave absorber 11 on the surface, and includes tapered wall surface portions 12 a and 12 b and a cylindrical wall surface portion 13. Compared with the configuration of FIG. 1 in the first embodiment, the configuration of the second embodiment shown in FIG. 4 has two tapered wall surface portions 12a and 12b with a two-step inclination on the tapered wall surface portion 12. This is a technical feature.

  As shown in FIG. 4, by using the tapered wall surface portions 12a and 12b provided with two-step inclinations, there is an effect of further reducing unnecessary scattered waves from the tapered wall surface portions 12a and 12b to the object 3 to be measured.

  As described above, according to the second embodiment, the presence of unnecessary scattered waves is reduced, the propagation time of unnecessary scattered waves is increased, and unnecessary scattering is performed with respect to the time response of reflected waves from the entire object to be measured. A structure in which the wall surface structure around the object to be measured is cylindrical is provided so that the waves do not overlap. As a result, it is possible to suppress the arrival time of unnecessary scattered waves from overlapping with the time response of reflected waves from the entire object to be measured, and it is possible to remove scattered waves by gating in the time domain, resulting in deterioration in measurement accuracy. It is possible to realize an anechoic chamber that can suppress noise.

  Furthermore, by providing the tapered wall surface portion with two stages of inclination, it is possible to further reduce the generation of unnecessary scattered waves as compared with the configuration of the first embodiment.

Embodiment 3 FIG.
In the first and second embodiments, the case where the radio wave absorber 11 is provided on both the surface of the tapered wall surface portion 12 (12a, 12b) and the surface of the cylindrical wall surface portion 13 has been described. On the other hand, in this Embodiment 3, the case where the electromagnetic wave absorber 11 is not provided in the surface of the cylindrical wall surface part 13 is demonstrated.

  FIG. 5 is a diagram showing the shape of an anechoic chamber according to Embodiment 3 of the present invention. In FIG. 5, the anechoic chamber 10 includes a tapered wall surface portion 12 and a cylindrical wall surface portion 13. Compared with the configuration of FIG. 1 in the first embodiment, the configuration of the third embodiment shown in FIG. 5 is different in that the radio wave absorber 11 is not provided on the surface of the cylindrical wall surface portion 13. .

  As shown in FIG. 5, since the radio wave absorber 11 is not provided on the cylindrical wall surface portion 13, the level of the unnecessary scattered wave 22 scattered by the cylindrical wall surface portion 13 becomes stronger than in the first embodiment. However, since the unnecessary scattered wave 22 has a long propagation distance, this results in arrival outside the time response of the reflected wave 21 from the object 3 to be measured.

  Therefore, the unnecessary scattered wave 22 can be removed by hardware gating or software gating. As a result, it is possible to achieve the same measurement accuracy as that of the first embodiment, while reducing the cost by removing the radio wave absorber.

  As described above, according to the third embodiment, the presence of unnecessary scattered waves is reduced, the propagation time of unnecessary scattered waves is increased, and unnecessary scattering is performed with respect to the time response of reflected waves from the entire object to be measured. A structure in which the wall surface structure around the object to be measured is cylindrical is provided so that the waves do not overlap. As a result, it is possible to suppress the arrival time of unnecessary scattered waves from overlapping with the time response of reflected waves from the entire object to be measured, and it is possible to remove scattered waves by gating in the time domain, resulting in deterioration in measurement accuracy. It is possible to realize an anechoic chamber that can suppress noise.

  Furthermore, by removing the radio wave absorber on the surface of the cylindrical wall surface portion, it is possible to reduce the measurement accuracy while reducing the cost.

  In the third embodiment, the case where the radio wave absorber on the surface of the cylindrical wall surface is removed in the configuration of FIG. 1 in the previous first embodiment, but the configuration of FIG. 4 in the previous second embodiment. The same effect can be obtained when the radio wave absorber on the surface of the cylindrical wall surface is removed.

  In the first to third embodiments, the case where the radar cross section is measured by removing scattered waves by gating in the time domain has been described. However, the anechoic chamber of the present invention is not limited to this. Absent. The anechoic chamber of the present invention can also be applied to the case where the radar cross-section is measured from the measurement data of the near region that does not satisfy the far condition using the near field / far field conversion technique.

  1 transmitting antenna, 2 receiving antenna, 3 device under test, 4 measurement area, 10 anechoic chamber, 11 electromagnetic wave absorber, 12, 12a, 12b tapered wall surface portion, 13 cylindrical wall surface portion, 21 reflected wave, 22, 22a, 22b unnecessary Scattered waves.

Claims (3)

In order to irradiate the object to be measured with radio waves radiated from the transmitting antenna, receive the reflected wave reflected by the object to be measured by the receiving antenna, and calculate the radar cross section from the intensity of the reflected wave. In an anechoic chamber with a wall covering the object, the transmitting antenna, and the receiving antenna,
The wall surface is
A tapered wall surface provided to have an inclination in the vicinity of the transmitting antenna and the receiving antenna;
An anechoic chamber, comprising: a cylindrical wall surface provided so as to have a cylindrical shape around the object to be measured. In the anechoic chamber according to claim 1,
The anechoic chamber, wherein the tapered wall surface portion is provided with a two-step inclination. In the anechoic chamber according to claim 1 or 2,
The said cylindrical wall surface part does not have an electromagnetic wave absorber. The electromagnetic wave anechoic chamber characterized by the above-mentioned.

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