CRLH TL-Unit Cell Loaded Tri-Band Circularly Polarized Crossed Dipole Antenna

In this paper, two unit cells of a via-less Composite Right/Left handed Transmission Line (CRLH TL) are loaded on the arms of a reference double sided printed dipole antenna to achieve tri-band operation. A pair of CRLH TL loaded tri-band dipoles are crossed through a vacant printed ring to obtain a tri-band circularly polarized (CP) operation. A cavity backed reflector is used with the tri-band CP crossed dipole to get high gain with unidirectional pattern (front to back lobe ratio > 25 dB) and wider CP operating bandwidth in all the three resonant frequency bands. The measurement results on the fabricated prototype confirm that the proposed tri-band cavity backed CP crossed dipole antenna exhibits CP operating bandwidth (S-11 < -10 dB and Axial Ratio < 3 dB) of 1.22%, 3.69% and 10.78% centered at 1.64 GHz, 2.17 GHz and 2.69 GHz respectively.