Enhancing the gain of microstrip antennas at different frequencies with one substrate-superstrate structure

A dielectric superstrate with a high relative permittivity is used to enhan ce the gain of a probe-fed microstrip patch antenna. The gain as a function of frequency and distance between the patch and the superstrate is investi gated experimentally. Under the resonance conditions for a high gain, the m aximum gain call be obtained at only one frequency point with a fixed super strate. It is discovered in our measurement that the maximum gain frequency can be adjusted by changing the distance between the patch and the superst rate. Using a dielectric superstrate with epsilon(r) = 10.5, a 10 dB gain i ncrement is obtained in the measurement. (C) 2000 John Wiley & Sons, Inc.