Measurements of the scattering matrix of obstacles in multimode wave guides.

Abstract

Accurate experimental determination of the impedance of obstacles in multimode waveguides is of continuing interest. The scattering matrix of a narrow, resonant, (half-wave) shunt slot in the broad face of an x-band multimode waveguide is determined experimentally and compared with present theory. A high power, (10 watt), traveling-wave tube is used in conjunction with thermistors and power meters for essentially dc measurement of attenuation and phase. Difficulties associated with modulation and crystal detection are discussed. Appreciation is due Professor R. M. Johnson of the faculty, U.S. Naval Postgraduate School, for technical advice and equipment.