Antipodal Vivaldi antenna with novel differentially fed structure for lowering cross-polarisation level
A novel differentially fed double-slot structure with two metal layers is proposed for an antipodal Vivaldi antenna. When fed differentially, the slots can have their E-field vectors summed to an E-field vector parallel to the layers, which endows the antenna with a significantly lowered cross-polarisation level by comparison with a typical antipodal Vivaldi antenna whose E-field vectors in the slot are skewed to the layers. A wideband balun based on a double-sided parallel stripline is used to realise the demanded differential feeding. The simulation and measurement are carried out to validate the remarkable characteristic of a two-layer structure, which is simpler than a three-layer structure of a balanced antipodal Vivaldi antenna.
