Synthesis of dispersionless zero group delay line for series-fed antenna arrays

Series-fed antenna arrays always experienced beam-squinting issue. Zero group delay(ZGD) element providing a potential solution for squint-free beamforming in series-fed antenna arrays. In this paper a novel synthesis approach for dispesionless optimized zero group delay line is proposed for the first time. Polynomial synthesis based approach is adopted which provides more design flexibility. Complete design steps followed by a synthesis example of flat magnitude and ZGD responses is presented. The exact agreement between the polynomial and coupling matrix based responses validate the proposed synthesis method.