Sierpinski Monopole Antenna Reconfigurable System using Hairpin Bandpass Filter Sections

In this paper, the design and development of a Sierpinski monopole gasket antenna reconfigurable system cascaded with two hairpin bandpass filter sections is presented. The reconfigurability is achieved by incorporating PIN diode switching mechanism to select the appropriate filter section to resonate the antenna at a desired frequency of interest. The proposed structure is aimed to be operated at 3.5 GHz and 7.5 GHz with good amount of gain, bandwidth along with the reduction of interference at the receiver. The proposed model is verified using the commercially available simulating software CST Microwave suite and a prototype is fabricated and tested accordingly. The simulated results are compared with the measured values and the corresponding results are presented. The simulated results shows that the antenna is resonating at 3.5 GHz and 7.5 GHz for a measured values of 3.48 GHz and 7.5 GHz with the appropriate selection of the switching mechanism. The antenna demonstrates a gain of 9.8 dBi and 6.2 dBi when simulated corresponding to a measured values of 10.1 dBi and 7.1 dBi respectively. The antenna offers a bandwidth of 60 MHz and 100 MHZ when simulated and 50 MHz and 180 MHz after the practical measurement at the operational frequencies. Nearly a 26 dB of separation of measured power levels between the operating frequencies can be observed at the receiver. The structure is better suitable for the Cognitive Radio applications as it offers better values of gain, bandwidth and reduced interference levels at the receiver along with design flexibility.