A Wide Band Circularly Polarised Microstrip Antenna with a Single Feed

A novel circularly polarised (CP), single-fed microstrip antenna is presented. The antenna consists of stacked structure of a rectangular patch over a rectangular ring. The proposed design has a reduced antenna size as compared to the conventional CP microstrip antenna at a given operating frequency. The impedance and axial ratio bandwidths are large and CP radiation quality is excellent over the entire upper hemisphere. These antennas feature more than 9dBi gain. The proposed antenna is suitable for global positioning system (GPS) applications.