JP2009236718A - Antenna measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein an antenna pattern is conventionally measured by stopping a turntable at each measurement angle, measuring gain with a spectrum analyzer, and performing this over the whole angle of a defined angle range, so that the pattern measurement requires a huge amount of time since the turntable is stopped at each measurement angle. <P>SOLUTION: A sample is continuously turned at a constant speed over the measurement angle range, video signal data is continuously acquired on an A/D board during the turn, then only A/D conversion data corresponding to each measurement angle calculated based on the rotation speed is extracted from the acquired data, and FFT arithmetic processing is performed. Thus, the antenna gain at each angle is calculated, and the antenna pattern is measured. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an antenna measurement apparatus for measuring gain characteristics of an antenna.

  Conventionally, an antenna control device is connected independently to each of a receiver, a turntable control device, and a computer, and a receiver interface circuit and a turntable control device interface circuit are provided inside the antenna control device, thereby providing antenna performance. There is known an antenna measurement apparatus that can shorten the measurement time (see, for example, Patent Document 1). By using this antenna measurement device, put the antenna specimen on a turntable installed in an anechoic chamber or dark box, rotate the antenna beam by rotating the turntable, and measure the gain at each rotation angle, The antenna pattern of the specimen can be measured (for example, see Patent Document 2).

Japanese Patent Application Laid-Open No. 7-229942 JP-A-9-178790

  In a conventional antenna measurement device, for example, a turntable on which an antenna specimen is mounted is stopped at each measurement angle, and an antenna gain at the angle is measured by a spectrum analyzer, and this is performed at all angles within a specified angle range. And the antenna pattern was measured. When performing this measurement method, it is necessary to repeat a series of steps of moving the turntable, maintaining the posture of the specimen at each measurement angle, and measuring the antenna gain for the measurement angle. For this reason, enormous test time is required when performing antenna pattern measurement in a wide angle range with fine angle steps.

  In the FMCW radar, the antenna gain can be measured by monitoring the video signal obtained from the frequency shift component of the transmission signal and the reception signal. For this FMCW radar, a measuring apparatus that can efficiently perform antenna pattern measurement is desired.

  The present invention has been made to solve such a problem, and measures the antenna gain at each angle while continuously operating the specified range at a constant speed without stopping the rotation of the turntable. With the goal.

An antenna measuring apparatus according to the present invention includes a turntable for rotating an FMCW radar antenna at a constant speed,
An A / D converter for continuously sampling and A / D converting video signals from the FMCW radar antenna;
A synchronization control unit that synchronizes the rotational speed of the turntable and the sampling rate of the A / D conversion unit, a recording unit that continuously records output data from the A / D conversion unit, and a recording unit that records the data A data extraction unit for extracting the output data of the A / D conversion unit corresponding to a predetermined rotation angle in the turntable with respect to the output data of the A / D conversion unit, and fast Fourier transform for the data extracted by the data extraction unit An FFT calculation unit that performs processing calculation and calculates antenna characteristics for each rotation angle;
It is equipped with.

  According to the present invention, the antenna pattern of the FMCW radar antenna can be measured while rotating the turntable at a constant speed, and the measurement time can be shortened.

Embodiment 1 FIG.
1 is a diagram showing a configuration of an antenna measurement apparatus according to Embodiment 1 of the present invention.
In the figure, an antenna measuring apparatus includes an anechoic chamber or dark box 1, a turntable 2, a specimen 3, a calculator 4, an A / D board 5, a horn antenna 6, a horn antenna 7, and a delay line 8. It is prepared for. As the specimen 3, an FMCW radar antenna having a transmission antenna and a reception antenna is used. The FMCW radar antenna transmits a transmission radio wave subjected to FMCW modulation from the transmission antenna, receives a reflected wave from the surroundings or the target by the reception antenna, and obtains a beat obtained by frequency mixing of the transmission signal and the reception signal. The signal is obtained as a video signal. The distance and speed of the target signal can be obtained by performing a fast Fourier transform (FFT) process on the frequency shift component in the up phase and the down phase of the video signal. The A / D board 5 is mounted on the computer 4, and a general-purpose A / D board capable of high-speed sampling is used.

  The specimen 3 is placed on the turntable 2 in the anechoic chamber or the dark box 1. The specimen 3 transmits a transmission radio wave and receives the signal by the horn antenna 6. The signal received by the horn antenna 6 is delayed by a delay line 8 composed of a plurality of waveguides, coaxial lines, and the like. The signal delayed by the delay line 8 is output to the horn antenna 7, and the signal is returned from the horn antenna 7 to the specimen 3. The specimen 3 receives the transmission radio wave output from the horn antenna 7 and obtains a video signal by frequency mixing of the transmission signal and the reception signal. The obtained video signal is output to the A / D board 5. The A / D board 5 can output digital data of a deviation component of a transmission / reception signal detected by the specimen 3 by AD converting the video signal. The turntable 2 receives the synchronization signal output from the computer 4 and is controlled to rotate at a constant rotation speed in accordance with the synchronization signal.

  FIG. 2 is a diagram showing a configuration of the computer 4 according to the first embodiment. FIG. 3 is a diagram showing an A / D conversion data acquisition operation by continuous rotation of the specimen, and FIG. 4 is a diagram showing an example of antenna pattern characteristics measured by the first embodiment. FIG. 5 is a schematic diagram showing the extraction operation of A / D data corresponding to the measurement angle.

  In FIG. 2, the computer 4 includes a synchronization control unit 11, a storage unit 12, a data extraction unit 15, and an FFT calculation unit 16. The synchronization control unit 11 sends a synchronization signal for controlling the turntable 2 to rotate at a constant speed. In addition, the synchronization control unit 11 sends a synchronization signal for synchronizing sampling to the A / D board 5. Thereby, as shown in FIG. 3, the rotation speed of the turntable 2 and the sampling rate of the A / D board 5 can be synchronized. Digital data of the video signal sequentially sampled by the A / D board 5 is input to the computer 4 and continuously recorded in the recording unit 12. The recording of the digital data is continuously performed for the rotational movement of the turntable 2 corresponding to all the angles in the angle range defined as the antenna of the specimen 3. After this rotational movement, the data extraction unit 15 recorded correspondingly for each predetermined rotation angle section on the turntable from the digital data continuously recorded in the recording unit 12, as shown in FIG. Output digital data of the A / D board 5 is extracted. At this time, the rotation angle can be calculated from the rotation speed of the turntable 2 and A / D data corresponding to the required angle can be extracted.

  Based on the output digital data of the A / D board 5 for each predetermined rotation angle section extracted by the data extraction section 15, the FFT calculation section 16 performs an FFT processing calculation for that section. Thereby, antenna gain data for each rotation angle can be calculated. After the antenna gain data at all the measurement angles is calculated by the FFT calculation unit 16, the antenna gain data for each measurement angle is connected to obtain the antenna gain angle characteristic (antenna pattern) as shown in FIG. Form.

  In the first embodiment, as shown in FIG. 3, by synchronizing the rotation speed of the turntable 2 and the acquisition timing of the A / D conversion data in the A / D board 5, without stopping the turntable halfway, Antenna gain measurement at all measurement angles can be performed in a continuously rotated state. Moreover, an antenna pattern can be obtained efficiently by calculating the angle characteristics of the antenna gain while rotating the turntable 2.

  Further, the video signal is continuously acquired by the A / D board 5 while the rotary table 2 is rotated at a constant speed over the measurement range, and the data is held by the computer 4. Thus, only the A / D data corresponding to the required angle due to the rotation of the turntable is extracted from all the data acquired after the rotation is completed, and the FFT calculation processing is performed only in that section to calculate the antenna gain at that angle. By doing so, antenna pattern characteristics can be obtained. Further, by synchronizing the rotation angle of the turntable 2 and the sampling timing of the A / D board 5, the antenna pattern can be accurately measured with fine angle steps.

  Accordingly, measurement data can be obtained by rotating the turntable while maintaining a constant speed, so that measurement efficiency is improved. In addition, by selecting an A / D board with high-speed sampling according to the required accuracy, batch measurement can be performed while rotating the turntable at high speed, and the time required for antenna pattern measurement can be greatly shortened. In particular, the antenna pattern is efficiently and accurately measured and measured by applying the antenna measurement apparatus according to the first embodiment in a system capable of measuring the antenna gain by monitoring a video signal such as FMCW radar. The antenna pattern can be quickly evaluated.

It is a figure which shows the structure of the antenna measuring device by Embodiment 1 which concerns on this invention. It is a figure which shows the structure of the computer 4 by Embodiment 1 which concerns on this invention. It is a figure which shows the acquisition operation | movement of A / D conversion data by the continuous rotation of a test body by Embodiment 1 which concerns on this invention. It is a figure which shows the example of a characteristic of the antenna pattern measured. It is a schematic diagram which shows the extraction operation | movement of A / D data for the measurement angle equivalent by Embodiment 1 which concerns on this invention.

Explanation of symbols

  1 Anechoic chamber or dark box, 2 turntable, 3 specimen, 4 computer, 5 A / D board, 6 horn antenna, 7 horn antenna, 8 delay line, 11 synchronization control unit, 12 recording unit, 15 data extraction unit, 16 FFT operation unit.

Claims (1)

A turntable for rotating the FMCW radar antenna at a constant speed;
An A / D converter for continuously sampling and A / D converting video signals from the FMCW radar antenna;
A synchronization control unit that synchronizes the rotation speed of the turntable and the sampling rate of the A / D conversion unit, a recording unit that continuously records output data from the A / D conversion unit, and a recording unit that records the data A data extraction unit for extracting the output data of the A / D conversion unit corresponding to a predetermined rotation angle in the turntable for the output data of the A / D conversion unit, and fast Fourier transform for the data extracted by the data extraction unit An FFT calculation unit that performs processing calculation and calculates antenna characteristics for each rotation angle;
An antenna measurement device comprising:

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