A Cavity-Backed Traveling Wave Antenna for Tri-Band GPS Applications

A cavity-backed tri-band antenna is proposed for the global positioning system (GPS) operating at 1176.45 MHz (L5 band), 1227.60 MHz (L2 band), and 1575.42 MHz (L1 band). The right-hand circular polarization (RHCP) of the proposed antenna is achieved by feeding a cross-type traveling wave antenna at one end and by terminating with a load at the other end. Without using the complicated feed network or the dual-fed structure, the proposed single-feed RHCP antenna gives wide impedance bandwidth ( ${\rm VSWR} ), wide axial ratio ( ${\rm AR} ) bandwidth, and high RHCP gain ( $ > 4 \hbox{dBic}$ ).