A polarisation agile T-shaped slot antenna fed from balanced microstripline

A microstrip fed T-shaped slot antenna element exhibiting polarisation agility is considered. The radiating element is located perpendicularly and in close proximity to a balanced microstripline which can support either an even-mode or an odd-mode. Predictions of the T-slot operation, at resonance, are obtained from a hybrid moment method analysis which incorporates spectral domain Green´s functions. This analysis estimates the amount of power radiated from the axial leg of the T-slot which in turn allows an investigation to be carried out on the possible mechanisms for controlling the level of radiation. An experimental setup for testing the operation of the radiating T-slot is described. Measurements are taken of the power radiated from the axial leg of the T-slot in order to verify the theory. Further measurements demonstrate control of the co-polarised and cross-polarised radiation levels.