This chapter elaborates in detail on the microstrip patch antenna, which is widely utilized in the receivers of radio telescopes, as well as in the wireless communication industry today. Several models have been developed to analyze and design the patch antennas. The three most common ones are the transmission line model, the cavity model, and the Method of Moments model. Apart from this, the important parameters used in characterizing the patch antenna are also covered, which are its gain, efficiency, directivity, radiation pattern, return loss, bandwidth, and polarization. This is followed by the introduction of the radiation regions, which are basically classified as the Fresnel region and the Fraunhofer region. Finally, the dual-frequency microstrip patch antenna is introduced. Three popular approaches adopted for the design are orthogonal-mode polarization, multi-layer patching, and reactive loading.
