MODIFIED TRANSMISSION LINE MODEL EQUATIONS FOR MICROSTRIP ANTENNA DESIGN

Abstract

Microstrip antennas are becoming more and more popular as the drive towards miniaturization continues. Therefore, the need for accurate models is growing. Not only accuracy is required, but also numerical efficiency, in order that the models are suited for computer-aided-design (CAD) procedures involving optimization. The transmission line model equations are used in the design of microstrip antennas. However, the level of accuracy can be low and several iterations required in optimization for better results. A modification of the dimensions obtained from TLM method is modified before CAD application for higher accuracy. In this work the transmission line model equations were modified by a factor and simulated. Simulations were carried with the FDTD method of CST microwave Studio. Four different substrates, namely FR-4 Rogers 5870 Roger RT 6010 Roger RT 5880 with same thickness (1.6mm) but different dielectrics were tested experimentally with the modified equations and compared with the conventional transmission line model at 1.75GHz. The three antenna parameters used for the studies were the return loss, S11, the voltage standing wave ration VSWR and the radiation patterns. For the four substrates used, the modification revealed improvements in the parameters of interest, namely, the return loss, voltage standing wave ratio...