Controlled capacitance and inductance behaviour of L-shaped defected ground structure for coplanar waveguide

The behaviour of the electromagnetic field in an L-shaped defected-ground structure (DGS) for a coplanar waveguide (CPW) has been investigated and the parameters affecting the inductance, the capacitance and the resistance are separately determined. Numerical experimentation of the effect of different design parameters has been carried out, which leads to a very wide variation of the band-stop frequency (2.8-10.5 GHz). Based on parameter sweeping, two wideband band-stop filters have been designed using four cascaded cells of double-sided, two-section, L-shaped DGS. The central frequencies achieved are 6.0 and 3.7 GHz and the band-stop widths are 2.8 and 2.0 GHz with rejection larger than 30 and 25 dB, respectively. All numerical investigations have been confirmed experimentally and excellent agreement has been achieved.