Circularly Polarized Antenna Based on Mu-negative Transmission Line

A circularly polarized (CP) antenna based on mu-negative (MNG) transmission lines (TLs) is presented. The antenna consists of two pairs of resonators for two orthogonal polarizations. The 90 degrees phase difference between them is achieved by detuning the corresponding resonance frequencies. The simulation results show that the 10 dB bandwidth (BW) of 29 MHz and 3 dB axial ratio (AR) BW of 7 MHz are obtained at 1.5 GHz. Also, the right-hand (RH) CP gain is 2.22 dBic in broadside direction and the minimum 3 dB AR beamwidth of 116 degrees is simulated at phi = 60 degrees. The results indicate that the antenna is suitable for the applications demanding for wide coverage area such as global position system (GPS) and wireless local area network (WLAN).