Design of irregularly shaped patch antennas by using the multiport network model

The multiport network model (MNM) is an analytical method that is used to analyze microstrip antennas. MNM is based on defining ports along the periphery of the patch and evaluating the impedance matrix corresponding to these ports by using the Greenpsilas function for the cavity under the patch. For regular rectangular, triangular and circular patches, analytical expressions for the Greenpsilas function are available. In the analysis of irregular patches, Greenpsilas functions cannot be calculated explicitly and segmentation and/or desegmentation techniques [2] are used in conjunction with the MNM method. The term ldquoirregularly-shaped patch antennardquo refers to a microstrip antenna whose patch geometry is designed in order to fulfill a specific antenna property such as compactness, wideband characteristics or multi-resonant operation [3]. In this paper, our main concern is to optimize the input impedance function for an irregularly-shaped microstrip antenna by utilizing the MNM together with the desegmentation method. The variation of the input impedance with respect to the antenna dimensions is studied to investigate the potential utilization of MNM as a building block for a design tool that will be developed to optimize the dimensions of irregularly-shaped patch antennas.