Phase radiation characteristics of an open-ended circular waveguide

Analytic expressions for phase radiation characteristics of a semi-infinite open-ended circular waveguide regardless of its aperture size and operating frequency have been obtained by making use of the rigorous Weinstein theory. The analysis of phase radiation patterns has been carried out for the dominant mode (TE/sub 11/) as well as for the high order modes TM/sub 01/ and TE/sub 01/, both for single and multimode propagation. The measurement of radiation characteristics of an open-ended circular waveguide has been carried out at the DTU-ESA Spherical Near-Field Antenna Test Facility. Theoretical results are in good agreement with the experimental ones.