Publica
Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Spherical Wave Expansion With Arbitrary Origin for NearField Antenna Measurements
 IEEE Transactions on Antennas and Propagation 65 (2017), Nr.8, S.43854388 ISSN: 0018926X ISSN: 00961973 

 Englisch 
 Zeitschriftenaufsatz 
 Fraunhofer FHR () 
Abstract
The farfield radiation pattern of an antenna under test (AUT) can be derived via a spherical wave expansion of nearfield antenna measurement data. The transformation as well as the measurement time scales with the number of spherical mode coefficients which depends on the radius of the sphere enclosing the antenna. In existing transformation procedures, the radius is measured from the center of the measurement sphere. Thus, the radius increases for an offsetmounted antenna so that more spherical mode coefficients are required to represent the electromagnetic field. In this communication, a procedure is proposed where the origin of the spherical wave expansion can be specified independently of the measurement sphere. With this procedure, the number of coefficients can always be minimized by selecting an expansion origin that minimizes the sphere enclosing the AUT. A translated expansion origin requires to include the probe pointing direction in the probe response constant calculation. This is achieved by Euler rotations of the probe receiving coefficients. The benefits of the procedure are demonstrated by measurements of an offsetmounted AUT.