NESTED CIRCULAR ELLIPTICAL SHAPED MIXED LOOP RESONATOR BASED BANDPASS FILTER FOR MICROWAVE APPLICATIONS

An elliptical thumb printed nested circular mixed loop resonator (MLR) is introduced in this article to design a multiple bandpass filter for microwave applications. The proposed structure is composed of a series of loop resonators on a Rogers RT-5880 dielectric substrate, where the overall system is developed into a 377 Omega framework. Similar structure is designed on both sides of the substrate and an investigation is made on scattering parameters, relative permittivity, permeability, refractive index and current distributions. The 12 x 14 mm(2) structure is designed and evaluated by a simulation software CST microwave studio and the metamaterial characteristics have been classified by Nicolson-Ross-Weir method at the filtering frequencies. The proposed filter shows resonances at 2.65 GHz, 5.85 GHz, 7.12 GHz, and 8.59 GHz, and the measured results are compared with the simulated ones. With a favorable design and double-negative characteristics, this design is suitable for multiple bandpass filter particularly for S, C, and X-band applications.