A New Hybrid Chamber for Generating a Spectrum of Oblique Incident Plane Waves at the DUT

Artikel i vetenskaplig tidskrift, 2021

A novel type of hybrid measurement facility comprising a chamber antenna array (CAA) inside an overmoded waveguide is proposed and analyzed numerically. The reflecting walls of the metal rectangular waveguide (WG) are used in conjunction with a CAA to synthesize obliquely incident plane wave (PW) fields at the device under test (DUT). This enables increased flexibility in emulating almost any PW multipath testing conditions in the WG chamber without the high cost and complexity of classical anechoic measurement systems employing relatively large phase-steered plane wave generators. A modeling framework is proposed that has been used to devise first-order design rules (e.g. the number of independent propagating modes, dimensions of the WG, CAA, and DUT). Afterwards, an optimally beamformed CAA example is presented to numerically validate the quality of the on- and off-axis plane wave fields in the test zone. This study shows design trade-offs between the amplitude ripple in the DUT region, the total power focused in this region, the DUT size and the angle of incidence.