Circularly polarized single-fed microstrip patch for wireless communications

For more than 25 years the circularly polarized single-fed microstrip patch have been considered to be extremely narrow-band. The performances reported are almost exclusively related to single patches printed on a dielectric substrate, which partially explains the frequency characteristics. The antenna proposed is a variation of the 'almost-square' patch and exhibits a theoretical axial ratio of less than 2.5 dB over a 10% bandwidth. The antenna was designed for PCN and PCS applications.