Method for eliminating multipath interference in antenna testing environment by adopting frequency difference technology
A technology of multi-path interference and frequency difference, applied in the direction of antenna radiation pattern, etc., can solve the problems that the test accuracy of antenna pattern is difficult to reach ±1dB, multi-path interference, uncontrollable, etc., and achieve low-parameter test improvement, high gain, and reduction effect of influence
Inactive Publication Date: 2012-11-07
NORTHWESTERN POLYTECHNICAL UNIV
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Problems solved by technology
[0003] In the microwave anechoic chamber, as the test frequency band decreases, the multipath reflection on the side wall increases, making it difficult for the test accuracy of the antenna pattern to reach ±1dB; the frequency band below 100MHz deteriorates to more than ±2dB
In the field test, due to the uncontrollable external environment, the multipath interference is more serious
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[0034] Now in conjunction with implementation steps, accompanying drawing, the present invention will be further described:
[0035] 1) When measuring antennas in a microwave anechoic chamber, the frequency domain response includes multipath interference in addition to the direct signal. Let the straight-line distance between the transmitting and receiving antennas be d, and the distance traveled by the multipath interference be r. The amplitude of the direct wave signal is The phase of the direct signal is The attenuation coefficient of the absorbing material is Γ (a complex number less than 1), and the magnitude of multipath interference in the frequency domain response is The phase of multipath interference is Therefore, a comprehensive model of the direct signal and multipath interference in the antenna measurement system in the microwave anechoic chamber can be established, and its mathematical expression is: Among them, G t is the gain coefficient of the transmi...
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The invention relates to a method for eliminating the multipath interference in an antenna testing environment by adopting a frequency difference technology, which has the technical characteristics that on the basis of the stepping frequency test, an amplitude and a phase of each frequency point in a frequency response are inspected by a frequency difference method; and for two groups of test data of adjacent frequencies, due to a small frequency interval (such as 2MHz), the amplitudes of the two groups of data can be approximately considered equal, but the phases of the two groups of data can have great difference. By analyzing a phase transfer relation of a test system, the difference in direct waves of the adjacent frequency points and the phase variations of multipath signals is inspected. After the frequency difference technology disclosed by the invention is adopted, direct signals can be separated from the frequency response so as to fulfill the aim of eliminating the multipath interference.
Description
technical field [0001] The invention belongs to the field of antenna testing, and in particular relates to a method for eliminating multipath interference signals in an antenna testing environment and improving the accuracy of measuring antenna parameters (including pattern, gain, and other parameters) by using frequency difference technology. Background technique [0002] To measure the actual radiation performance of an antenna, precise measurements are required. There is multipath interference in the test environment (microwave anechoic chamber or open field). In conventional frequency domain measurements, the strong reflection of the main lobe beam when it points to the side wall will increase the level of the side lobe; when the performance of the absorbing material is not enough Ideally, the multipath interference signals from the side wall and rear wall will seriously affect the test accuracy. Especially in the low frequency band, this phenomenon is more obvious. ...
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Inventor 张麟兮郭静远张曼张颖军宋鹏魏世京张琦
Owner NORTHWESTERN POLYTECHNICAL UNIV