New Low-Pass Filter Design Using Compensated Microstrip Capacitor and Coupled Meander Defected Ground Structure (DGS)

In this paper, we propose a new compact DGS lowpass filter with broad stop-band and low insertion loss in the pass-band. The philosophy of the structure behind this new microstrip low-pass filter is simple as it is composed of a pair of meander DGS-slots and open-stubs. The direct electromagnetic coupling and slow-wave effect have been employed to design the proposed filter using DGS and multilayer method. The optimized low-pass filter has shown higher compactness, broad stop-band and sharp transition characteristics. The design equations are derived using a lumped-element equivalent circuit model of a parallel L-C resonator. In order to validate the feasibility of the proposed design, a low-pass filter with 0.1-dB ripple is designed, fabricated, and measured. The experimental results have shown a good agreement with the simulation and analytical results.