Study and Enhanced Design of RF Dual Band Bandpass Filter Validation and Confirmation of Experimental Measurements

Dual band bandpass filter is designed and optimized for RF wireless applications. The performances of that RF dual band filter are improved especially parameters describing the insertion loss, return losses and rejection. Dual band bandpass filter using stub loaded resonators is designed and characterized. Theoretical results are compared with experimental data. This comparison shows that the magnitude of reflection coefficient S11 from ADS simulation is better than 28.0 dB, and the insertion loss S21 is less than 0.5 dB. The two rejections are also better than 32.0 dB. The simulated results also show that two central frequencies are located at desired 1.82 and 2.95 GHz. Comparison of measured and simulated results shows frequency drift. The main reason for this frequency shifting is due to some uncertainties. These are obviously due to geometrical and physical parameters H and r respectively of Duroid substrate used during design and measurements.