Novel planar microstrip low pass filters using electromagnetic band gap (EBG) structures

This paper investigates and proposes novel planar microstrip low pass filters (LPF) employing EBG structures in the form of slots etched in the ground plane. The main feature of EBG structures is the existence of a band gap in the frequency spectrum of a propagating electromagnetic wave. In the present design, a band stop with a deep rejection ratio is obtained at the higher end of the pass band of the filters. The present LPF are designed with EBG lattice shapes include rectangular holes, split ring holes, triangular holes, complementary split ring resonator holes, circular holes, and 2-shape holes. The frequency responses of the filter include the scattering parameters, the input impedance, and the loss factors are obtained. The effect of the structure parameters such as the number of lattices, lattice shapes, lattice spacing, and the dielectric substrate thickness are studied. The numerical results obtained using an analytical technique with the aid of a numerical package based on the method of moment (MOM).