Applications Of Antenna Near/far-Field Measurement

Antenna measurement is a very important way to design and verify modern higher capability antenna. This paper researched some practice applications of antenna measurement in near-field antenna engineering based on the basic theory of plane/cylinder near-field measurement.At first, based the classic plane wave mode expansion theory and scattering matrix theory, the expression of near-field planer wave expansion were driven and with the probe-compensated the expression for the far-field pattern driven by near-field data were also given. It discussed the select rule of sampling plane, sampling space and the discrete calculate expression of probe. Then, under the cylinder coordinate, the expression of the cylinder wave expansion near-field coupling, the rule of sampling plane and sampling space were also presented.Taking the practice near-far field antenna measurement system as an example, it analyzed the structure of system and the component of hardware and the function of developed system test soft. Aiming at the phase center and circular polarization antenna test questions, the moving reference point was used to obtain the relationship between coordinate systems and phase center of the radiation phase pattern. Then, it used the ellipse perpendicular decomposition theory to analyze the calculate ways of AR, gain of ellipse polarization antenna. The test data showed that the practical values matched with the theory ones very well.At last, the near-field diagnosis of array antenna was researched in detail using the pattern multiplication method. In other words, the amplitude and phase of every elements of the antenna could be obtained only to know the far field of array antenna and single element with no requirements for the excitation of each element, and then error element could be distinguished. It could get a higher precision within a certainly range in that error dimension of the diagnosis excitation coefficient was very low. It satisfies the need of the practice diagnosis test applications.