Design and fabrication of microstrip lowpass filter using asymmetric hairpin resonator

In this letter, a compact microstrip lowpass filter (LPF) is designed using serial connecting of two modified asymmetric hairpin resonators. The proposed design is consists of four open-circuited stubs that are used to suppress spurious harmonics in the stopband. The proposed filter has wide-stop band with attenuation level better than -28 dB from 2.16 up to 26.1 GHz and sharp roll-off. The proposed LPF has -3 dB cutoff frequency equal to 2.11 GHz, wide stopband width around 12th harmonic suppression and insertion loss less than 0.1 dB at about 85% of the passband. The excellent agreement is observed between the simulated results and measured values of the fabricated LPF.