7.5 Planar Antennas
Patch antennas (also referred to as microstrip antennas) are two-dimensional metallic strips on a dielectric substrate with a ground plane on the down side of the substrate [5, 14]. Patch antennas may differ in shape (rectangular, circular, triangular). Most commonly rectangular patch antennas are used. Figure 7.15 shows a rectangular patch with length L and width W.
Figure 7.15 Geometry of a rectangular patch antenna.
Patch antennas have some useful properties: The low-cost production process already known from planar circuits can be applied to the antenna structure as well. So, antennas, matching networks, power dividers, filters and combiners can be produced in one manufacturing step. Furthermore, patch antennas are light-weight and robust and have low profile. Patch antennas can be designed to conform to curved surfaces (conformal antennas), for example on vehicles and aircrafts. Due to the permittivity of the substrate the antenna is reduced in size. A drawback of patch antennas are their small relative bandwidth compared to dipole antennas.
7.5.1 Rectangular Patch Antenna
7.5.1.1 Radiation of a Single Patch Element
A rectangular patch antenna is a metallic strip (length L, width W) on a laterally-infinite dielectric substrate with a metallized back side. The ground plane extends to infinity as well. The substrate has a height h and a relative permittivity ...
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