Assessment of Irregular Sampling Near-Field Far-Field Transformation Employing Plane-Wave Field Representation

Abstract. The far-field behavior of an antenna under test (AUT) can be obtained by exciting the AUT with a plane wave. In a measurement, it is sufficient if the plane wave is artificially generated in the vicinity of the AUT. This can be achieved by using a virtual antenna array formed by a probe antenna which is sequentially sampling the radiating near-field of the AUT at different positions. For this purpose, an optimal filter for the virtual antenna array is computed in a preprocessing step. Applying this filter to the near-field measurements, the far-field of the AUT is obtained according to the propagation direction and polarization of the synthesized plane wave. This means that the near-field far-field transformation (NFFFT) is achieved simply by filtering the near-field measurement data. Taking the radiation characteristic of the probe antenna into account during the synthesis process, its influence on the NFFFT is compensated. The principle of the plane-wave synthesis and its application to the NFFFT is presented in detail in this paper. Furthermore, the method is verified by performing transformations of simulated near-field measurement data and of near-field data measured in an anechoic chamber.

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Plane wave based near-field far-field transformation with adaptive field translations

2011 XXXth URSI General Assembly and Scientific Symposium ◽

10.1109/ursigass.2011.6050251 ◽

2011 ◽

Author(s):

Carsten H. Schmidt ◽

M. Ayyaz Qureshi ◽

Thomas F. Eibert

Keyword(s):

Plane Wave ◽

Near Field ◽

Far Field ◽

Field Transformation

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Probe-corrected near-field to far-field transformation using multiple spherical wave expansions

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078720000136 ◽

2020 ◽

Vol 12 (6) ◽

pp. 447-454

Author(s):

Fernando Rodríguez Varela ◽

Belén Galocha Iragüen ◽

Manuel Sierra Castañer

Keyword(s):

Near Field ◽

Spherical Wave ◽

Irregular Sampling ◽

Field Pattern ◽

Far Field ◽

Transformation Technique ◽

Sampling Schemes ◽

Field Transformation ◽

Simulated Field ◽

Far Field Pattern

AbstractNear-field to far-field transformations constitute a powerful antenna characterization technique for near-field measurement scenarios. In this paper, a near-field to far-field transformation technique based on multiple spherical wave expansions (SWEs) is presented. Thanks to its iterative matrix inversion nature, the approach performs the transformation of fields measured on arbitrary surfaces. Also, irregular sampling schemes can be incorporated. The proposed algorithm is based on modeling the antenna fields with not one, but several SWEs distributed over its geometry. Due to the high number of SWEs, their truncation number can be arbitrarily reduced. Working with expansions of low order allows us to incorporate the probe correction in the transformation in a very simple way, accepting any type of probe and orientation. Only the probe far-field pattern is used, thus working with its full SWE is avoided. The algorithm is validated using simulated field data as well as measurements of real antennas.

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