Network modeling of an inclined and off-center microstrip-fed slot antenna

This paper describes a general method for analyzing a microstrip-fed slot antenna with a view to developing an improved network model featuring an inclined and off-center slot. The network model consists of an ideal transformer, a radiation conductance, and extended slotlines terminated by short circuit. The transformer turn ratio can be calculated by combining the reciprocity theorem with the spectral-domain immittance approach. The radiation conductance is determined by the radiated power from the slot in the forms of space and surface waves in the spectral domain. Then network models corresponding to several variations of the antenna are described and the series impedances are computed. The computed results using the network model are compared with the rigorous solution and measurements and good agreements are obtained.