Microstrip Patch Antenna for Radiolocation using DGS with Improved Gain and Bandwidth

This paper presents the analysis of compact triband microstrip patch antenna for radiolocation. The proposed structure shows the multi-frequency band operation and it covers C and X-band frequencies that are allocated for radiolocation application of radar. Firstly dual band frequency operation achieved by simple rectangular microstrip patch antenna with four rectangular slots and for getting triple band a cylindrical slot is cut on the patch. For improving the performance (gain, directivity & bandwidth) of microstrip patch antenna rectangular DGS (defective ground structure) is used. This antenna is designed on FR-4 substrate with dielectric constant 4.9 and thickness 1.8 mm and its size is 14 X 14 X 1.87 mm(3). The parameters of proposed antenna like return loss, VSWR and radiation pattern (gain, directivity and efficiency) are simulated and analyzed using commercial computer simulation technology microwave studio (CST MWS). By simulating proposed antenna we get three frequency bands which are 5.84-6.03GHz, 9.00-9.32GHz and 10.43-10.73GHz with resonant frequencies 5.9, 9.1 and 10.4GHz. The gain of proposed antenna is improved by using the DGS structure as the gain without DGS at resonant frequencies was 2.3, 5.8 and 4.6dBi and after DGS it was enhanced to 2.5, 6.1 and 5.3dBi. And the requirement for microstrip antenna VSWR <= 2 is full filled by all the resonant frequencies. The antenna structure is very simple, compact and occupies less space all these qualities make this antenna suitable for practical applications.