Independently Tunable Dual Band Antenna loaded with modified Split Ring Resonator with Circular Polarization Characteristics for Wireless Applications

In this work, a circularly polarized (CP) dual band corner extended slot antenna loaded with a split ring resonator (SRR), which is modified in its structure, is presented. The antenna operates in two bands. The lower resonance frequency is obtained due to the slot dimension. The slot antenna is excited using them microstrip feed line. The corner extended slot antenna produce two degenerative modes which are require to obtain CP in the lower resonant frequency. An SRR is etched on a corner of the slot structure to obtain the upper resonance frequency. The slot antenna produce magnetic field which is axial in direction to modified SRR and excites it. To achieve CP in the upper frequency band, strips with asymmetric in nature are introduced in the SRR which creates equal magnitude with a 90° phase. The CP antenna with dual band characteristics is capable of tuning the resonance frequencies and polarization sense independently in each frequency band. The designed antenna is operated at 1.58 GHz and 1.95 GHz. The simulated results shows that the lower resonant frequency has a −10 dB impedance bandwidth from 1.47GHz-1.62GHz and upper resonant frequency from 1.84 GHz-2.08 GHz. A 200MHz of axial ratio (<3dB) bandwidth in the lower resonant frequency and 130MHz in the upper resonant frequency is obtained respectively. The simulated radiation efficiency of >75% is achieved in both bands.