Broadband rectangular waveguide launcher design using dual source excitation

Rectangular waveguides are an essential tool for measuring the intrinsic complex properties of simple dielectric media. This is because rectangular waveguides have a simple geometry, high power handing capability, and simple field expressions. The major trade off for using a rectangular waveguide in material measurements is the relatively limited single mode operational frequency range in comparison to waveguides with other geometries. In order to address the excitation of higher order electromagnetic modes, a novel dual source excitation rectangular waveguide design is proposed. Symmetric placement of two excitation pins in the launcher produces an increased single mode bandwidth when driven with a source which can operate in either common or differential excitation. The way in which this is accomplished is through the linear superposition of the fields excited by transverse electric (TE) and transverse magnetic (TM) modes supported by the waveguide launcher.