Compact wide-band electromagnetic-band-gap-based filters for microstrip antenna design in harmonic-tuned transmitters

Compact, wide-bandstop electromagnetic-band-gap (EBG)-based microstrip filters are studied for harmonic-tuned integrated power amplifiers to be used in high-efficiency transmitters operating in Ku band. An accurate characterisation of EBG filters is performed by means of a full-wave modal analysis based on a periodic method of moments in the spatial domain. The synthesis of optimal values for the antenna input impedance at the fundamental, second and third harmonic frequencies is achieved through suitable perturbations of the unit-cell geometries, which lead to appropriate tapered filter configurations. Numerical simulations of the input impedance and of the radiation properties are provided for a circular patch antenna by means of different independent commercial software in order to validate the proposed approach.