Analysis and characterisation of coupled transmission lines loaded with complementary spiral resonators

In this study, the behaviour of coupled microstrip transmission lines loaded with complementary spiral resonators (CSRs) is analysed in depth. CSRs are constitutive elements for the synthesis of metamaterials with negative effective permittivity which allows the suppression of undesired signals at a given frequency band. Several test prototypes have been characterised and modelled for transmission, crosstalk interference, isolation and signal integrity (SI). Experimental results reveal that CSRs provide a good solution to reduce crosstalk between parallel transmission lines in the radio frequency band with a low impact in terms of the SI. A design methodology based on the equivalent circuit model for the description of the proposed structures, including transmission lines and coupling parameters, is provided.