Design and Performance Analysis of Frequency Scanning Microstrip Array Antenna for Vehicular Adhoc Network

Abstract

For wireless communication system it is impossible to think a system without antennas because it is the one to enable the transformation of energy between a guiding device and the free-space. Antennas come in variety of shape, size and type. In order to achieve increased performance array of antennas are implemented. They bring benefits such as high gain, bandwidth, efficiency etc. specially beam forming and beam steering are their major advantage. Typical adhoc network, VANET (Vehicular Adhoc Network) works with the beam forming and steering technologies .Currently VANET is using Omni directional antenna. That means improvement in overwhelming signals is highly demanded .This can be achieved by beam steering and beam forming techniques. The shifting of beam mainly is achieved by either by using phase shifters or FSA (Frequency Scanning Antenna). This thesis work presents rectangular frequency scanning Microstrip patch array with a resonant frequency of 23 GHz for Vehicular Adhoc network application.23 GHz is recently allotted for dedicated short range communication (DSRC) by Korea Communications Commission (KCC).Which makes it ideal for VANET applications. Multi port feeding configuration combined with inset feeding has been used, the direction of the beam is swept or scanned by changing the frequency of the each element in the array, meaning beam steering is done by changing the frequency of the system .Change in the frequency of the system can be achieved in many ways. Mainly, by changing the path length of the each radiating element or using LWA (leaky wave antennas) the first approach is used in this work. That is the steering of the antenna beam by varying the frequency of each radiating element fit to the antenna is given focus. Computer Simulation Technology (CST) is used for designing, testing and Matlab for analytical modeling. Accordingly taking frequency range from 22.5GHz to 23.5GHz with steps of 0.125GHz, steering angle of 90 degree from-45.and 45 has been accomplished as result frequency sensitivity (scanning range/BW) of 90 degree has been obtained. Single, 2x1, 4x1, 6x1, 8x1 FSA antennas have been designed and compared with most relate FSA designs. A gain of 10.32dBi, angular beam width of 23.55dB, Side lobe level of -23.1, Radiation and total efficiency of 60% and 55.8% has been attained at the center frequency.