Modified Smith-chart representation as applied to microstrip antenna design for wireless LAN applications

In this paper, the frequency-dependent effective permittivity concept is applied to construct a frequency-dependent (lossy) Smith-chart to analyze microstrip structure characteristics. The proposed algorithm depicting the dynamic permittivity of the microstrip structure directly leads to a convenient and modified Smith-chart representation that includes the frequency-dependent influence of fringing field and the lossy characteristics cohesively. The efficacy of the model is illustrated with an example concerning a microstrip patch antenna for wireless LAN applications. Relevant simulations show that the input impedances calculated from the model are more accurate than those from the previous model in the literature by comparing to the measure results, as illustrated with an example of a patch antenna. This model is compatible for CAD efforts with MATLABtrade facilitating fast and user-friendly implementations. Further, as far as the author knows of, this is the first attempt in depicting the characteristics of a microstrip antenna via Cole-Cole diagram format