Diagnosis and tuning of filtering antenna based on extracted coupling matrix

A general method is proposed in this paper to extract the two-port coupling matrix of filtering antennas. By using the passivity and the realizability properties of a filter network, the rational polynomial forms of S-parameters can be obtained from the reflection and realized radiation efficiency of a filtering antenna. The coupling matrix is then obtained with transformation and optimization. After the coupling matrix is reestablished, the diagnosis and tuning of filtering antenna can easily be carried out. Our method has been validated with the successful tuning of a stacked patch antenna.