Wide-band and high-gain microstrip antenna with thick parasitic patch substrate

A stacked microstrip antenna which is composed, of a fed patch, a parasitic patch and a thick parasitic patch substrate, is proposed. Its characteristics have been investigated in detail using the FDTD method. The behavior mechanism for the high gain performances of the stacked microstrip antenna is explained clearly for the first time. The characteristics of the stacked antenna depend on the patch separation distance, that is, the thickness of the parasitic patch substrate. When the patch distance is approximately half a wavelength in the dielectric, an electric standing wave contributing to the radiation exists in the cavity between patches, and the amplitude of the electric fields becomes large. Because the thick dielectric is inserted in the space between the fed and the parasitic patches, the height of this stacked antenna becomes low. By adjusting the patch distance, the patch size and the feed point, the stacked microstrip antenna which has both wide bandwidth and high gain is successfully realized.