External substrate perforation applied to patch antennas for mitigating surface wave effects

Patch antennas are useful in a very broad range of applications due to their simplicity, in both operation and fabrication, conformability and integrability with planar circuitry. The problem is that patch antennas do not perform well on high dielectric constant substrates used in compact micro/millimeter-wave circuit fabrication. This makes the integration of a patch antenna on the same substrate as the input/output circuitry difficult. Thus, there is considerable interest in overcoming the undesirable features of thick and high dielectric constant substrate for patch antennas without sacrificing any of the desired features, namely, small element size and bandwidth. To this end, substrate perforation exterior to a patch antenna is suggested. The idea is to lower the effective dielectric constant of the substrate surrounding the patch while not affecting the substrate under the antenna. This concept was studied using the FDTD technique. The change in the effective dielectric constant surrounding the patch antenna has been observed to help mitigate the ill effects of patch antennas on thick, high dielectric constant surfaces.