Archimedean microstrip spiral antenna loaded by chip resistors inside substrate

Abstract

An ultra-wide-band (UWB) microstrip spiral antenna is proposed. The antenna is resistively loaded inside the substrate to maintain a good circular polarization on the bandwidth. The main performances are a very thin thickness (/spl lambda//100 at the lowest operating frequency), good impedance matching and right hand circularly polarized patterns over a 9:1 bandwidth.