A Compact Second-order Chebyshev Bandpass Filter Using U-shaped Resonator and Defected Ground Structure

A compact bandpass filter using U-shaped resonators and Defected Ground Structures is proposed and designed at 5.8 GHz. The U-shaped resonators are placed around an indirectly coupled feed line while the Defected Ground Structures are positioned beneath them. The U-shaped resonator and U-shaped Defected Ground Structure are responsible for the high and low band rejection respectively. The proposed bandpass filter obeys the second order Chebyshev response which has low insertion loss of - 1.87 dB, high rejection level and a sharp roll-off performance. The design is carried out using CST Microwave studio. The design is verified by fabricating and measuring the prototype in the laboratory. A good agreement is observed between the simulated and measured results.