Analysis and Design of Planar Extremely-Wideband Bandpass Filter With Broad Stopband Performance

Abstract

A novel planar bandpass filter design achieving an extremely wide passband (1 GHz to 8 GHz) and a broad stopband is proposed. The design integrates highpass filter principles into the transmission line structure, enabling the wide passband. Moreover, modified short-circuited coupled-line pairs are employed to address the fabrication limitations of high-impedance microstrip lines on printed circuit boards. This approach results in a fractional bandwidth of 155.6%, exceeding conventional designs. Furthermore, the filter achieves significant harmonic suppression with 30 dB attenuation in the stopband. Overall, this design offers a promising solution for applications requiring extremely wideband filtering with superior out-of-band rejection.

Keywords

• Bandpass filter
• extremely-wideband
• planar circuit
• wide stopband