1. Haneishi, M., and Suzuki, Y.: ‘Circular polarization and bandwidth’, James, J.R., Hall, P.S., Handbook of microstrip antennas, (Peter Peregrinus, London, UK 1989)
2. Kraus, J.D.: ‘Antennas’, (McGraw-Hill, New York, USA 1988),2nd Chap. 7
3. Aperture Fed Wideband Circularly Polarized Rectangular Stair Shaped Dielectric Resonator Antenna
4. Wideband Circularly Polarized Antenna With L-Shaped Slot