Via Hole and Parasitically Coupled Microstrip Antennas of Arbitrary Shape in Multi-Layered Substrates

Microwave antenna performance optimization may be achieved by shaping the antenna properly, as well as with the correct antenna excitation design. This article presents the theoretical development of an algorithm which is very suitable for the design of microstrip antennas of arbitrary shape in multi-layered substrates. It includes the design of the antenna excitation either through parasitic coupling, or through a via hole transition from a microstrip line. The algorithm is applied for the design of a circularly polarized notched ring microstrip antenna coupled parasitically to a microstrip transmission line. The performance of via hole excitation of a rectangular patch antenna is also discussed.