Conversion factors for the power radiated by a small slot in loaded rectangular waveguide

The radiation characteristics of slot radiators in uniform rectangular waveguide have been extensively documented, both theoretically and experimentally. However, to avoid grating lobes, or to accommodate frequency scanning, in slotted waveguide arrays, the waveguide used is often partially filled with a periodic structure, or with dielectric, to reduce the guide wavelength. This communication describes conversion factors which have been generated to permit the radiation strengths of nonresonant slots, in such waveguides, to be estimated from known results for uniform empty waveguides.