Design Of Dual-band Left-handed Materials With Double-left-handed Characteristics

Compared with common materials in nature,the left-handed material(LHM)has a series of unusual properties,such as double negative properties(both permittivity and permeability are less than zero),negative refraction characteristic(the refraction index is negative,i.e.the incident wave and refracted wave are located in the same side of normal line),backward wave characteristic(group velocity and phase velocity have adverse direction)and left-handed characteristic(the vectors E,H,and K would form a left-handed triplet instead of a right-handed triplet).It is beneficial to employ LHM structure in the circuit for the reduction of device size,the broadening of frequency band and the improvement of device performance.The application of LHM can have positive effect on the future of science and technology,economic and social development because of its great potential and value.Therefore,the LHM has become the world's attention from the beginning and has been developed rapidly in the past ten years.More recently,in order to enhance information capacity and accommodate the rapid development of modern science and technology,more and more broadband and multiband work equipment have been used.Therefore,the design of LHM with the broadband and multiple frequency resonant characteristics has become the trend of the times.Therefore,the research on the LHM trends to the structure with broadband and multi-band characteristics.The traditional design about multi-band only includes one left-handed band,while the LHM structure with double left-handed characteristics can satisfy the increasing requirement of broadband and multiband.In this paper,a novel LHM structure with dual left-handed characteristics is realized through the combination of split-ring resonator(SRR)and defected ground structure(DGS)in order to satisfy the demands of the growing multiband for 2.4GHz and 5.8GHz.The proposed LHM structure exhibits negative permittivity,and permeability in the targeted frequency ranges.The effective permittivity and permeability curves are obtained using NRW method.Both the effective permittivity and permeability of the structure is negative.The advantages of small size,easy processing for the dual LHM provides a certain reference value for the application of new material device.