DESIGN OF MULTIPLE BEAMS FORMING NETWORK FOR SWITCHED BEAM ANTENNA SYSTEM WITH

E -SHAPED MICROSTRIP ANTENNA

G. Purnachandrara Rao¹, Kshitiz Agarwal ¹ M. V. Kartikeyan¹, M. Thumm^{2, 3}

¹Department of Electronics & Computer Engineering

Indian Institute of Technology, Roorkee 247 667, Uttranchal, India

²Forschungszentrum Karlsruhe, IHM, Postfach 3640, D76021 Karlsruhe, Germany

³Universitaet Karlsruhe, IHE, D76131 Karlsruhe, Germany

Abstract – This paper presents the design of a multiple beams generation network for switched beam antenna systems with E-shaped microstrip antenna. In todays wireless mobile communication the major problem is system capacity. As the number of mobile subscribers increases, the ability to provide communication for all subscribers decreases. Switched beam and adaptive array antennas are the two proposed techniques to increase the system capacity. Microstrip substrates are used for the design of multiple beams formation networks and antennas. However microstrip antennas have very narrow bandwidth. In this paper we solve the narrow bandwidth problem of microstrip antennas. This paper consists of the design of single, 2 and 4 element antennas. For multiple beams generation the Butler matrix approach is used. Quadrature hybrid, crossover and phase shifters are employed to construct the Butler matrix, and these are designed with microstrip technology. Two different microstrip substrates are used for the design of the proposed system and an air gap of 0.5 cm is taken between the two substrates. The designed antennas have bandwidths of 20%, 32% and 45% and gains of 8dB, 10dB and 12 dB respectively with single, 2 and 4 element antennas.

Index terms: - E – shaped microstrip antenna, switched beam antenna system, dual parallel slots, Butler matrix, quadrature hybrid, cross over and phase shifter.