Improved transmission line model for input impedance of rectangular microstrip antennas with multi-dielectric layers

A number of investigations have been carried out to determine the electrical characteristics of microstrip antennas with multi-dielectric layers using spectral domain analysis and other full-wave analysis methods. However, the accurate numerical methods are time-consuming and are not easily included in a CAD package. The transmission line models (TLM) are still the fastest models used to analyze rectangular microstrip antennas. A new improved TLM is presented which refines the original approximations and extends them to the more general configurations with multi-dielectric layers. The improvements of the present model are due mainly to two techniques. First, a lossy TLM is introduced with an attenuation constant /spl alpha/ taking account of all of the losses (dielectric, conductive, radiation and surface wave losses). Secondly, the multi-dielectric layer rectangular microstrip antenna is treated as a multi-layer microstrip line, which is equivalent to a normal microstrip line on one substrate by means of the conformal mapping approach.<>