Mutual coupling reduction of microstrip antennas using electromagnetic band-gap structure

Microstrip antenna arrays have found broad applications in recent years and the reduction of mutual coupling is an important criterion in their design. The FDTD method is applied to analyze probe fed patch antennas and the simulated results agree well with the experimental results of R.P. Jedlicka et al. (see IEEE Trans. Antennas Propagat., vol.29, p.147-9, 1981). The mutual coupling of patch antennas on a high dielectric constant substrate, which is of growing interest due to its compact size and conformability with MMIC, is characterized in detail. Such antennas have larger mutual coupling than antennas on a low permittivity substrate because of the pronounced surface waves. The electromagnetic band-gap structure introduced by D. Sievenpiper et al. (see IEEE Trans. MTT, vol.47, p.2059-74, 1999) is then employed to inhibit the surface waves so that the mutual coupling is greatly reduced.