A Compact Diplexer with a Split-Ring Resonator Junction

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Diplexers are three-port filtering devices with a junction connecting two channel filters; the common port connects to an antenna which serves the two channel filters bearing the second and the third port. In the design of diplexers, the technique used in connecting the two channel filters is of great importance to the designers. This is because it determines the size, the effectiveness of signal splitting and combining as well as the ease in implementation. In this article, an asynchronously tuned double split-ring resonator (SRR) was used in joining the two channel filters. Without incurring any extra space for the junction, the SRR, being a dual-mode resonator, also functioned as a resonant pole for each channel filter. A diplexer operating at 2 GHz and 3 GHz with 4% fractional bandwidths and 20 dB return loss has been demonstrated. The interactions between the SRR and the channel filters were investigated. Good agreement between the simulated and the measured responses was achieved.


Original languageEnglish
Pages (from-to)2385–2390
JournalMicrowave and Optical Technology Letters
Issue number9
Early online date27 Jun 2017
Publication statusPublished - Sep 2017