A design approach for compact ultra-wideband bandpass filter based on hybrid microstrip coplanar waveguide resonators
Keywords:
Ultra-wideband, Coplanar waveguide, Microstrip resonator, Bandpass filter, Microwave circuitsAbstract
In this paper, we present a simple hybrid coplanar waveguide (CPW) and microstrip ultra-wideband (UWB) bandpass filter using five quater-wavelength resonators, three microstrip ones on the top and two CPW ones on the bottom side. The proposed filter exhibits a quasi-elliptic function response, with one finite-frequency transmission zero closer in the low side and two finite-frequency transmission zeros in the high side of the passband. The experimental filter shows the measured 3-dB fractional bandwidth of 80% at a center frequency of 6.02 GHz, with the mesured insertion loss is 0.6 dB. This design not only improves the harmonic-suppression characteristic in highfrequency stop-band but also reduces the size of filter with 15 × 18 (mm). The filter will have great potential applications in UWB microwave circuits and systems, especially, in C-band radar systems.
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