In this research study, knitted fabrics were produced on an E=12 gauge electronic flat bed knitting machine for the High frequency attenuation characterization in the frequency range of 1 GHz - 1,5 GhZ. Conductive yarns with different linear resistances were knitted into non-conductive base fabrics made from double covered PA 6.6 core spun lycra yarns. Two different design approaches have been applied for manufacturing of samples. In the first approach, conductive yarn has been knitted in plain arrangement into elastomeric interlock base fabric. In latter case, the base fabric was produced with elastomeric yarns in an interlock arrangement and a conductive yarn was embedded in this substrate to create a series of single loop structures. Effect of design approaches and conductive yarn linear resistance on high frequency attenuation properties of conductive knitted samples was investigated. It was observed while design differences have more effect on attenuation characteristics of samples, linear resistance values of conductive yarns have also slightly affected the properties of samples.