INVESTIGATIONS ON CROSS-SLOT APERTURE-COUPLED CIRCULARLY POLARIZED MICROSTRIP ANTENNAS AND ARRAYS

Abstract

The circularly polarized microstrip antennas are developed to satisfy the requirements of advance military and commercial applications such as mobile satellite communication, direct broadcast satellite (DBS) system, remote sensing, wireless local area network, blue-tooth personal network and global system of mobile communication (GSM), the global positioning system (GPS), etc. In many microstrip antenna applications, system's requirements can be met with a single patch element. In other cases, however, systems require higher antenna gains and a wide bandwidth while maintaining a low profile structure, which calls for the development of microstrip arrays In this dissertation, cross-slot aperture-coupled feed circularly polarized microstrip antenna and array using sequential rotation technique, operating at 2.45 GHz, have been analyzed and designed. The effect of various geometrical parameters on the antenna performance, using simulations, has also been investigated. It is found that the single element antenna can attain a VSWR impedance bandwidth of 9% and gain of 9 dB. To widen the axial ratio bandwidth, simulation and hardware implementation of 2x2 array configuration was done using sequential rotation technique. In this dissertation, impedance bandwidth of 13.2 % and axial ratio bandwidth of 10 % has been obtained by implementing a 2x2 array configuration. Also, a 4x4 array is simulated that shows enhanced VSWR bandwidth of about 33%.