The Quad-band Antenna with Circular Polarization Diversity

THE QUAD-BAND ANTENNA WITH CIRCULAR POLARIZATION DIVERSITY Introduction  Multi-band antennas with polarization diversity useful for many wireless systems  Proposes a quad-band antenna with linear and circular polarization diversity Antenna Design  Based on a monopole antenna with L-shaped and slotted radiators  Generates 4 impedance bands from 3-15 GHz  Modes studied using characteristic mode analysis Performance  Achieves left-hand circular polarization (LHCP) in bands 1 and 3  Linear polarization in bands 2 and 4  Good impedance matching, gain, efficiency and AR bandwidth Circular Polarization Mechanism  Orthogonal modes with 90 degree phase difference  Equal amplitude orthogonal modes enable circular polarization  Current distribution varies over time to give LHCP Radiation Characteristics  Omnidirectional patterns suitable for mobile applications  Reasonable axial ratio beamwidth obtained  LHCP in broadside direction, slanted due to asymmetric feeding

Conclusion  Simple quad-band antenna with linear and circular polarization diversity  Could support diverse wireless applications requiring multiple bands