Radial loaded transformed radial stub for LPF stopband extension
Yeo, Kiat Seng
Date of Issue2012
School of Electrical and Electronic Engineering
A low pass filter with ultra-wide band rejection and compact size using a proposed radial loaded transformed radial stubs is introduced and investigated. The implemented unite cell low pass filter with 1-dB cutoff frequency fc of 3.2 GHz demonstrates stopband rejection up to 11.8 fc i.e. 38 GHz. The design is further extended to the high-order LPF through cell cascading. The implemented four-cell LPF with fc of 3.6 GHz demonstrated 35dB rejection from 4.8GHz to 39GHz, 50 dB rejection from 5.4 GHz to 26 GHz (7.2 fc) and 20dB rejection from 4.4 GHz to 50 GHz (13.8 fc). The measured passband insertion loss is less than 1.7 dB, and group delay is from 0.45~0.8 nS. The size of the four-cell low pass filter is only 0.33λg × 0.135λg, (λg is the guide wavelength at center cutoff frequency) without using any lumped elements.
DRNTU::Engineering::Electrical and electronic engineering
Progress in electromagnetics research letters
© 2012 EMW Publishing. This paper was published in Progress In Electromagnetics Research Letters and is made available as an electronic reprint (preprint) with permission of EMW Publishing. The paper can be found at the following official DOI: [http://dx.doi.org/10.2528/PIERL12012009]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.