Wideband bandpass filter with ultra-wide stopband based on cross-shaped parallel coupled lines

Abstract

A broadband out-of-band rejection capability and multiple transmission zeros of wideband bandpass filter are proposed and validated in this article, which employ quadruple anti-parallel coupled-line structures to form a novel cross-shaped resonator planar topology. The centered frequency of the single wideband bandpass filter designed for verification is located at 2.4 GHz (f₀) with a fractional bandwidth of 50%. The interaction of crossed multiple anti-coupled lines with a lowpass-loaded fan constitutes the wideband with nine transmission zeros in the 5 f₀ frequency range for improved suppression extending to 26.5 GHz (10.7 f₀) with a suppression level of 12.5 dB. Moreover, the designed prototype filter is implemented and tested with a measured minimum insertion loss of 0.9 dB. Good agreement between the measured and simulated results is attained to successfully validate the correctness of the proposed design approach.

KEYWORDS:

• Wideband bandpass filter
• cross-shaped
• anti-parallel coupled lines
• multiple transmission zeros
• out-of-band suppression

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is supported by the Guangzhou Key Research & Development Program, Major Science and Technology Projects [grant number 202206070001] the Research and Development Program in Significant Area of Guangdong Province [grant number 2020B0101040002]. The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.