A Wideband Spoof Plasmonic Circularly Polarized Antenna

a unidirectional wideband spoof plasmonic (SP) circularly polarized (CP) antenna is proposed in this paper. Four rotating SP dipoles are excited by a sequential-phase feed network using parallel transmission lines, obtaining 90 degrees phase shift and equal power division. Owing to the subwavelength property of spoof plasmonics, our proposed wideband SP CP antenna has a smaller size without parasitic elements. The fabricated antenna has a size of 75mmx75mmx30.83mm (0.67 lambda(0)x0.67 lambda(0)x0.28 lambda(0), where lambda(0) is the free-space wavelength at the center frequency), and an average CP gain of 8.74dBic with less than 0.65-dB variation within the 3-dB ARBW. Measured results show an impedance bandwidth (IBW) for S-11<-10dB of approximately 47.2% (2.09-3.38GHz) and a 3-dB axial ratio bandwidth (ARBW) of approximately 33.9% (2.23-3.14GHz), agreeing well with the simulated results.