Microstrip Hairpin Bandpass Filter for Radar S-Band with Dumbbell-DGS

One of the possible errors in radar communication is the presence of unwanted frequencies that are still passed by the radar system, causing performance to decrease. This paper proposes a bandpass filter (BPF) design for S-Band radars that work in the range of 3 GHz. A Bandpass filter is designed using the microstrip hairpin technique plus the dumbbell-Defected Ground Structure (DGS) method. This study aims to prove that the selection of DGS forms and effectiveness in optimization can provide better results. The band-pass filter is realized using the RO4350-B material with a relative dielectric constant of 3.48 and a thickness of 1.524 mm. The results obtained from the realization of band-pass filters show S11 of −31.822 dB, S21 of −0.829 dB and VSWR of 1.502. Filters work on ranges 2.850 – 3.02 GHz with a bandwidth of 170 MHz. From the parameters of the results obtained, the filter designed is following the specifications specified. Addition of dumbbell-DGS also gives better results than the form of a square groove-DGS.