Circularly Polarized High Gain Antenna using array of parasitic patches on superstrate layer

This paper proposes a circular polarized microstrip antenna fed high gain antenna using array of square and circular parasitic patches on a superstrate layer. Here parasitic patches are used to enhance the gain of antenna. The antenna structure consists of a microstrip antenna fabricated on FR4 substrate and placed at 1mm from finite ground plane. This MSA feeds array of square parasitic and circular parasitic patches fabricated on a FR4 superstrate. The patches on superstrate are suspended in air at about lambda(0)/2. Circular polarization is obtained by diagonal feeding of microstrip antenna and using two shorting pins. The array size of parasitic patches is varied from 1x1 to 5x5. The printed MSA is fed by a 50 Omega coaxial probe. The VSWR is < 2 over 5.725 - 5.875 GHz, ISM frequency band. The antenna provides increase in gain from 8 dB to 14 dB gain as we increase the array of parasitic patches from MSA0 to MSA 4x4 over 5.725-5.875 GHz. But gain decreases as we increase array of parasitic patches to 5x5. So maximum gain can be obtained in circular polarized antenna is by using 4x4 arrays of parasitic patches. The antenna structure also provides more than 70 % efficiency.