Bandpass filters based on coupled split ring resonators for surface waves on planar Goubau lines

This paper demonstrates a method for enhancing the performance of recently introduced compact bandpass filters for terahertz surface waves on single wire waveguides, the socalled planar Goubau lines (PGLs). It is firstly shown numerically and validated experimentally that a gapped PGL loaded with a pair of split ring resonators (SRRs) acts as a bandpass filter. The concept and simulation result are validated through experiment. Furthermore, in order to achieve an improved frequency response, a third-order filter based on coupled SRRs is proposed. It is shown that while the size of the proposed filter is further reduced, it additionally benefits from a higher inband transmission, improved selectivity, and a controllable wide bandwidthAli K. Horestani, Withawat Withayachumnankul, Abdallah Chahadih, Abbas Ghaddar, Mokhtar Zehar, Derek Abbott, Tahsin Akalin, and Christophe Fumeau