Design, Simulation and Fabrication of Microstrip Hairpin and Interdigital BPF for 2.25 GHz Unlicensed Band

A frequency hopping spread spectrum data link that works in the unlicensed frequency band of 2.2 GHz to 2.3 GHz, needs to be compliant with EMI/EMC Issues to reject or attenuate the unwanted input signals (interferences) and also preventing of spreading out spurs and harmonic signals. Because of unlicensed band and no affordable commercial filters, two types of microstrip band pass filters called hairpin and interdigital were designed, simulated and fabricated on FR4 substrate as application specific filters. The results showed achievement of needed performance.