Compact SRR based band stop filter for isolation in WLAN band in MIMO

Abstract

The advent of metamaterials has enabled the researchers to design materials which are non-existent in nature. This exclusive property has opened new horizons for the RF and microwave engineers to customize materials that possess the unique properties of negative permittivity and negative permeability which otherwise cannot be realized using natural materials. When carefully designed, SRR on a substrate exhibit band reject characteristics. These SRR based bandstop filters are extremely beneficial in applications such as multiple input multiple output (MIMO) systems. In this paper two different SRR band stop filters are presented. The designed filters produce isolation responses, satisfying IEEE 802.11a/b/g WLAN band requirements i-e., (2.41 to 2.49 GHz, 5.15 to 5.35 GHz and 5.725 to 5.825 GHz). The first design is a doubly SRR to produce a band reject response from 1.86 GHz -2.65 GHz. The second designed filter is a closed loop SRR with T-shaped strips. It has been designed to provide high reflectivity and wide bandwidth rejection at 5 GHz band i.e., from 5 GHz -5.75 GHz. The simulation of SRR band stop filters has been carried out in CST microwave studio.

A Novel Dual-Passband Net-Shaped FSS Structure Used for Mimo Antennas

“…The main parameters that will determine the overall frequency response of an FSS include dielectric substrate properties, element shape geometry, inter-element spacing (cell-size or periodicity) and incidence angle of spatial waves on the surface [4][5][6][7]. Different FSS structures have been investigated by microwave engineers in the development of high performance spatial filters, such as reconfigurable frequency selective surfaces [11][12][13][14], multilayered selective filters [8], periodic arrays on anisotropic substrates [9,10], and FSSs with geometric fractal elements [15][16][17][18][19].…”