Accurate analysis and design of circularly polarized dual-feed microstrip array antenna using multiport network model

Microstrip patch antennas (MPAs) with circular polarization are used in many communication and radar systems. There are several methods and models in order to analyze and design of these antennas. Multiport network model (MNM) is considered as one of the best models of MPAs. This model includes several circuit networks that are connected to each other and each of them represents one characteristic of the MPA. Solution of this model is equivalent to calculation of the input and radiation parameters of the antenna. In this paper, a circularly polarized 2times2 array antenna with sequentially rotated microstrip elements is designed using the MNM. For producing the circular polarization, besides the sequentially rotation technique, two probe feeds are used in the E-plane and H-plane of each elements, respectively. These probes have currents with equal amplitudes and 90 degree phase difference