FDTD Analysis of Microstrip Patch Antennas and Arrays on High Dielectric-Constant Substrate Surrounded by a Soft-and-Hard Surface

摘要

The surface-wave diffraction at the edge of a finite size substrate with a high dielectric constant is the dominant mechanism affecting the radiation pattern of a microstrip patch antenna fabricated on this material. A soft-and-hard surface (SHS) can be used to block the surface waves from propagating outward along the dielectric substrate, thus reducing the unwanted diffraction. Microstrip antennas surrounded by the SHS are analyzed using the finite-difference time-domain (FDTD) technique that implements the SHS boundary conditions using a modified subcell model. A square patch antenna on the LTCC-GL660 multilayer substrate and a phased array of 2 X 2 patches are investigated as benchmarks and it is shown that the gain of the patch with SHS increases by more than 3 dB, while the front-to-back ratio is higher than 24 dB.