The near-field measurement and near-far field transformation of microwave scattering of a plate at different distances

Author(s):  
Chonghua Fang ◽  
Qifeng Liu ◽  
Fan Ding ◽  
Xiaonan Zhao ◽  
Jing Xiao
2021 ◽  
Author(s):  
Rubén Tena Sánchez ◽  
Lars Jacob Foged ◽  
Manuel Sierra Castañer

Multiprobe spherical near-field measurement is a potent tool for fast and accurate characterization of electrical properties of antennas. The use of fast switching in one axis, an azimuth positioner, and a near- to far-field transformation allows a substantial time reduction in antenna measurements while maintaining high-quality results. On the other hand, conventional emissions EMC measurement systems are typically based on detecting the radiated spurious emissions by a device at different frequencies. The systems usually work in far-field (or quasi-far-field conditions), performing the measurements either at 3 or 10 meters. Measurements under these conditions take space and time. Moreover, the systems are not cost-effective for pre-compliance purposes where pre-testing of the device should provide valuable information and confidence about the DUT before performing a compliance test. This chapter analyzes the possibility of cost and space reduction for EMC systems based on multiprobe near-field measurement systems in combination with OTA (over the air measurements), reference-less systems, spherical near-field transformation, phase reconstruction, modal filtering, source reconstruction, and software-defined radio receivers.


2013 ◽  
Vol 11 ◽  
pp. 47-54
Author(s):  
R. A. M. Mauermayer ◽  
T. F. Eibert

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.


2009 ◽  
Vol 2009 ◽  
pp. 1-7 ◽  
Author(s):  
R. Rammal ◽  
M. Lalande ◽  
E. Martinod ◽  
N. Feix ◽  
M. Jouvet ◽  
...  

The aim of this work is to get far field radiation patterns for any radiating source from transient acquisition, in a large frequency range. An outdoor transient Ultra-Wideband near-field measurement base will be installed, a single time pulse radiated by the source will cover the desired spectrum, and the accurate determination of far field radiations will be accomplished by means of cylindrical waves' modal development. This method uses simplified test equipments, easy to be installed, and it reduces measurement costs.


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