Design of Microstrip Low-Pass Filter Based on Six-Slit-Ring DGS
A novel six-slit-ring defected ground structure (DGS) is presented in this paper. The location of the slit can shift the resonant frequency without changing the overall size of the DGS and its adjustment range can reach 8.81 GHz. By cascading three identical six-slit-ring DGS unit cells, a microstrip low-pass filter (LPF) can be realized. Its 3dB cutoff frequency is 7.27 GHz. The in-band insertion loss is below 0.35 dB and the stop-band width with 20 dB attenuation is over 8.12 GHz. To improve the out-of-band rejection of the filter, shunt branches were added on both sides of the microstrip line. Its 3 dB cutoff frequency is 8.285 GHz. The insertion loss is less than 0.81dB in the pass-band. The stop-band rejection is better than -40 dB at 11.36-20 GHz and the size of the filter is only 28 mm by 11 mm. The simulation results show that the proposed novel six-slit-ring DGS microstrip LPF has the characteristics of compact size, flexible adjustment, flat pass-band, wide stop-band and high selectivity.
Design of Compact Ultra Broad-Stopband Lowpass Filter
For miniaturization and harmonic suppression,a novel planar compact lowpass filter is presented in this paper.A conventional stepped-impedance lowpass filter is modified by some microstrip steps connected in 90° and some T-shaped transmission lines integrated into the lowpass filter.The proposed lowpass filter has the advantage of low insertion loss(below 0.5 dB at 0～4 GHz),ultra broad stopband(over 40 dB at 5～30 GHz) and compact size(50% reduction).Experiment validates the design concept.
Investigations of dielectric gratings using electrodynamic models based on volume integral equations
Eigenmodes of planar and cylindrical dielectric gratings (DGs) and electromagnetic wave scattering from multiplayer DGs are investigated. The DG characteristics are calculated using numerical-analytical solution of integral equations (IEs).