Compact resonant slot for waveguide arrays

The development of an I-shaped novel geometry for radiating slots entirely in the narrow wall of a waveguide is outlined. I2R losses in the metal of the waveguide wall are identified as an undesirable feature of impedance-loaded slots or slots of reduced height. The I-shaped geometry developed does not include these features, and is demonstrated to be a useful low-loss waveguide array element, offering a wide range of coupling values.