Microstrip Patch Antennas—Basic Characteristics and Some Recent Advances

The basic geometry of a microstrip patch antenna (MPA) consists of a metallic patch printed on a grounded substrate. Three commonly used feeding methods are coaxial feed, stripline feed, and aperture-coupled feed. The patch antenna idea was first proposed in the early 1950s, but it was not until the late 1970s that this type of antenna attracted serious attention of the antenna community. The microstrip patch antenna offers the advantages of low profile, conformability to a shaped surface, ease of fabrication, and compatibility with integrated circuit technology, but the basic geometry suffers from narrow bandwidth. In the last three decades, extensive studies have been devoted to improve the performance of this antenna and the MPA has found numerous applications in both the military and the commercial sectors. This article begins with a brief description of the modeling techniques and basic characteristics of the MPA. Methods of broadbanding, dual and multiband designs, size-reduction techniques, and design for circular polarization are then reviewed. The paper ends with some concluding remarks.