Switched beam triangular microstrip antenna fed by hybrid coupler

Recently, switched beam antenna system has been widely used in numerous applications such as in communication system, satellite system and modern multifunction radar. This is because of the ability of the switched beam antenna to reduce the existing interference and to improve the quality of transmission [1][2][3]. A switched beam system consists of a beam switching network and antenna array. A simple design of beam switching uses a 3 dB hybrid coupler. The 3 dB hybrid coupler is a directional coupler with a 90° phase difference in the output of the through and coupled arms [4]. In general the quadrature hybrid is one of the most popular passive circuits used for microwave and millimeter wave applications [5]. It is an important circuit element in microwave integrated circuits and can be used as a power divider, combiner or a part of mixer.