Design and analysis of novel DGS-loaded low-pass filter with wide stopband

Abstract

This article deals with design and development of a novel 7th order low-pass filter with defected ground structures for S-band applications. The proposed LPF structure was comprised of dumbbell shaped interdigital defected ground structures and open stubs as series inductor and shunt capacitor in the pass band. In addition, an equivalent circuit model was derived and optimized to achieve a 3-dB cut off frequency about 4 GHz with a reflection coefficient of better than −20 dB. Moreover, proposed low-pass filter was manufactured on a Rogers RO4003C substrate with a dielectric constant of 3.38, the dissipation factor of 0.0027. The developed LPF has a very flat pass-band with a transmission coefficient less than −0.5 dB and the measured transmission coefficient better than −18 dB in the passband (DC-3.6 GHz). Meanwhile, the prototype has a 20 dB harmonic suppression level in the frequency range from 5.54 GHz up to 43.5 GHz. Furthermore, the measured peak to peak group delay variation was less than 170 ps in the passband. The proposed filter has a very compact size of 195.3 mm2.

High isolation of SPDT PIN diode switch using switchable dumbbell-shaped DGS in millimeter wave 28 GHz band

“…The progression of research works on the DGSs in RF and microwave for the last 10 years have shown evidences of improvement towards design realizations and performances. DGS has several advantages on the circuit [12], unwanted frequency suppression [13]- [15], bandwidth enhancement of antennas [16], [17], size compactness [18], [19], high power handling capability [20], isolation in antenna designs [21]- [23], and compensating parasitic capacitance of switching element to improve isolation [24], [25].…”