Advanced development of traveling-wave antenna array (TWAA) as multioctave planar phased array

Full-fledged characterization of Traveling-Wave Antenna Array (TWAA) for wide-angle scan up to 60° off broadside over 2-12 GHz was first presented in 2015 IEEE Antenna Symposium by this author. Ironically, in the same Symposium, presentation by Neto and Cavallo stated that no “Connected Array” has yet reached a bandwidth of 2:1 due to poor cross-polarization higher than -10 dB. This paper shows that TWAA does not suffer from the high X-pol problem, based on recent measurements at both WEO and Georgia Tech. Plausible causes of the high X-pol problem are also discussed.