Analysis of multiband rectangular patch antenna with defected ground structure using reflection coefficient measurement

In this paper, a novel quad band antenna to operate at four different frequency bands is designed and simulated using Computer Simulation Technology (CST) Microwave Studio software. To achieve better performance of the antenna, various parameters were optimized using parametric analysis. During this analysis, various antenna parameters were need to be measured. The proposed antenna uses asymmetrical 'U' and 'T' shaped radiating elements printed on an FR-4 substrate with dimensions of 1.6 x 34 x 20 mm3. 3 . The measurement of various antenna parameters like reflection coefficient, return loss, radiation intensity are key tasks to be performed in the antenna measurement laboratory before going to the real time application. A stair case defected ground structure with rectangular center slot is used to attain a better bandwidth. The antenna resonates at four different frequencies 3 GHz, 4.8 GHz, 9 GHz, 13.2 GHz with operating bandwidths of 980 MHz, 2.05 GHz, 3.84 GHz, and 3.82 GHz respectively. The S 11 value at these resonant frequencies is measured as-23.6 dB,-29.4 dB,-34.2 dB,-49.05 dB respectively. The voltage standing wave ratio of the proposed antenna at four resonant frequencies is equal to one. The gain of the antenna is consistent throughout the four pass bands. The antenna is suitable for Bluetooth (2.4) GHz, WLAN (5.125-5.35) GHz and (5.725-5.825) GHz, WiMAX (5.25-5.85) GHz, C-band (3.7-4.2) GHz and Ku-band (12-18) GHz.