An antenna radiation characteristic acquisition method based on phase-free near-field measurement

Abstract

The invention discloses an antenna radiation characteristic acquisition method based on phase-free near-field measurement. The method comprises the following steps: firstly, acquiring electric field amplitude information of all sampling points on a closed curved surface in a near-field region which is not far away from an antenna to be measured, and then establishing two nonlinear relationships between electric field distribution on a certain spherical surface of the near-field region and amplitude data on a measurement surface through a spherical wave expansion theory; and finally, speculating electric field distribution on the target spherical surface of the near-field region by using a genetic algorithm; when the algorithm stops iterative optimization, the tangential electric field distribution of the spherical surface to be guessed being basically close to an ideal result, at the moment, calculating a weighting coefficient on the spherical surface to be optimized by utilizing a spherical wave mode expansion theory, and obtaining a far field through spherical surface near-far field transformation. The invention provides a technology suitable for measuring antennas of various specifications.

Description

technical field [0001] The invention belongs to the technical field of microwave measurement, in particular to a test method for reconstructing far-field radiation characteristics by using near-field phase-free data. Background technique [0002] Antenna measurement techniques mainly include far-field measurement, near-field measurement, and compact field measurement methods. The far-field measurement method is a direct measurement method, which obtains the far-field radiation characteristics of the antenna through certain mechanical control. The test distance R of the far field area of ​​the antenna satisfies λ is the wavelength, and D is the maximum size of the antenna; as the size of the antenna increases, it becomes unrealistic to measure the far field directly, especially when the test size increases and the frequency increases, it becomes very difficult to measure the far field , thus developing the antenna near-field measurement technology. This technology has the...

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Problems solved by technology

However, from the perspective of programming, the spherical near-field measurement technology is more complicated, while the planar and cylindrical near-field measurement is relatively simple; from the perspective of measurement difficulty and probe compensation, the mechanical control of the planar and cylindrical is relatively easy , and the measurement cost is low. However, there are problems such as truncation error when calculating the far-field radiation characteristics of the plane and cylindrical near-field measurements;

[0004] The development of near-field measurement technology has become a very mature and widely used method. It requires the amplitude and phase information of the electric field in the near-field region, both of which are indispensable; however, with the increase of antenna frequency, It becomes very difficult to obtain very fine and accurate phase information, especially in the submillimeter wave to millimeter wave band, the error of the probe antenna position, the temperature fluctuation of the device during the measurement process, the noise of the test system, the antenna probe under test and other The coupling effect between the two and various human factors, etc., make it very difficult for people to measure accurate phase information in the near-field area. Even if more reliable phase data can be obtained, a very high price will be paid. It requires very precise and expensive instruments, and ordinary laboratories cannot achieve high-precision phase measurement. Therefore, people began to imagine that very accurate far-field radiation characteristics can still be obtained under the condition of ignoring the phase signal. This is the phaseless antenna near-field technology that is getting hotter now

[0005] For now, there is a commonly used phase-free near-field measurement technology, which is the phase recovery technology. Generally, one or more sets of amplitude data in the near-field area are used to recover the phase data, and then the far-field data is calculated using strict mathematical transformation. For example, the Chinese patent with application number 201710676154.6 accurately calculates the far-field radiation characteristics based on the spherical tangential electric field amplitude data on two different radii in the near-field area. field measurement technology, and must measure the amplitude data on two measurement surfaces; in addition, this method puts forward high requirements for the quality of the initial phase

The Chinese patent application number 201610614730.X provides a method for measuring near-field antennas on arbitrary curved surfaces. However, the amplitude and phase data on discrete grid points must be obtained at the same time. When the frequency increases, this method will pay extra costs to obtain phase information, which will increase the cost of measurement

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