Broadband characteristics investigation of waves in a left-handed miniaturized waveguide loaded with ISRRs

In this paper, broadband transmission characteristics of waves in a left-handed miniaturised rectangular waveguide (LHMRW) loaded with improved split ring resonators (ISRRs), which shows that the bandwidth of negative permeability is up to 5.6 GHz by an optimization design, are investigated. Some unexpected phenomena such as the discontinuous left-handed passband below the cutoff frequency of the dominant TE mode, which cannot be transformed into a continuous one by any impedance matching approach, are observed. The EM field distributions in the LHMRW are calculated so as to explain these phenomena. Results show that the LHMRW can be considered as an open ended resonant cavity instead of a normal transmission structure. In addition, the backward wave inside the time domain in the LHMRW is directly observed.