Lowpass Filter with Hilbert Curve Ring and Sierpinski Carpet DGS

Good performance and compact size are the paramaters which are vital when desiging a filter. One of the creteria of good performance is selectivity. This research, conducted by Hilbert Curve Ring and Siepinski Carpet, is used as defected ground structure to overcome filter selectivity. By using three cascadeds Hilbert Curve Ring defected ground structure cells and three steps Sierpinski carpet, a lowpass filter is designed and fabricated. The measurement result for lowpass filterwith Hilbert Curve Ring defected ground structure has sharper selectivity with the cut off frequency at 2.173 GHz and the insertion loss value is 2.135 dB. While the measurement result for three steps Sierpinski carpet has the cut off frequency at 1.728 GHz and the insertion loss value is 0.682 dB

Modeling of Modified Split-Ring Type Defected Ground Structure and Its Application as Bandstop Filter

The shape of a popular split-ring defected ground structure (DGS) is modified by selecting different width of the sides with respect to microstrip line. The frequency characteristics of proposed DGS unit show an attenuation zero close to the attenuation pole frequency. The unit cell is modeled by 3rd order elliptical lowpass filter and an equivalent circuit is presented accordingly. For proposed DGS, both pole and zero frequencies are obtained at lower values compared to split-ring DGS unit with uniform width. The variation of the width of the sides, parallel to microstrip line influences pole frequency. Two DGS cells with different pole frequencies cascaded under High-Low microstrip line realize a sharp and deep bandstop filter. Three-cascaded cells underneath a highlow impedance microstrip line produce sharper and wider bandstop filter characteristics

Filter Designs Based on Defected Ground Structures

This chapter concentrates on the filter structures using Defected Ground Structures (DGS). Initially, this chapter discusses the limitations of Electromagnetic Band Gap (EBG) structures and the development of DGS structure from EBG structure. DGS is an area of increasing interest in EBG technology. Here the well-known dumbbell DGS structures’ features and physics are also discussed. New investigations are presented on the choice of geometrical shapes for the DGS structure as an element for the proposed filters. All the proposed DGS structures used to implement different types of filters (lowpass, bandpass, and bandstop) are validated

Design and optimization of a new compact 2.4 GHz-bandpass filter using DGS technique and U-shaped resonators for WLAN applications

The objective of this work is the study, the design and the optimization of an innovative structure of a network of coupled copper metal lines deposited on the upper surface of a R04003 type substrate of height 0.813 with a ground deformed by slots (DGS). This structure is designed in an optimal configuration for use in the design of narrowband bandpass filter for wireless communication systems (WLAN), the aim of use the defected ground structure is to remove the unwanted harmonics in the rejection band, the simulation results obtained from this structure using CST software show a very high selectivity of the designed filter, a very low level of losses (less than-0.45 dB) with a size overall size of 43.5x34.3 mm

Defected Ground Structure: Fundamentals, Analysis, and Applications in Modern Wireless Trends

Slots or defects integrated on the ground plane of microwave planar circuits are referred to as Defected Ground Structure. DGS is adopted as an emerging technique for improving the various parameters of microwave circuits, that is, narrow bandwidth, cross-polarization, low gain, and so forth. This paper presents an introduction and evolution of DGS and how DGS is different from former technologies: PBG and EBG. A basic concept behind the DGS technology and several theoretical techniques for analysing the Defected Ground Structure are discussed. Several applications of DGS in the field of filters, planar waveguides, amplifiers, and antennas are presented

Prototype of compact Microstrip lowpass filter for active phased antenna array with ultra-wide stopband using funnel shaped resonator

This paper deals with the design of a prototype microstrip filter, which would be suitable for integration into active phased array antennas. This novel compact microstrip lowpass filter is based on funnel shaped resonator and semi elliptical patches. The proposed filter is designed, modeled, and fabricated to achieve an ultra-wide stopband with a sharp transition band. Furthermore, the LC equivalent circuit and transfer function of funnel shaped resonator are extracted. The cut-off frequency of proposed filter at -3 dB is 1.4 GHz and this filter has an ultra-wide stopband begins from 1.66 GHz to 17 GHz with the suppression level of 20 dB. Moreover, this lowpass filter has a sharp transition band of 0.26 GHz and compact size of 0.138 λg ×0.05 λg. The proposed structure is printed on Rogers_Rt 5880 and the measured results are coincided with the simulation results

A New Lowpass Filter Unit Cell with Sharp Roll-off and Improved Stopband Performance in Coplanar Waveguide Technology

In this paper, a new compact unit cell for a coplanar waveguide (CPW) lowpass filter (LPF) is proposed. By combining a pair of coupled parallel stepped impedance resonators (SIRs) and high impedance short stubs in the CPW line, a fifth-order elliptic lowpass filter unit cell (LUC) is designed. The extra transmission zero introduced by parallel coupled SIRs is used to extend the stopband and increase the roll-off rate. The characteristics of the proposed LUC is investigated to achieve a sharp roll-off and a wide stopband. The measured results are in accordance with the simulated results. It has an insertion loss less than 0.9 dB from dc to 6 GHz, and a wide -15 dB stopband from 7.5 to 18 GHz. In addition, the filter dimensions are as small as 4.9 mm × 8.7 mm, that is, 0.046λg2, where λg is the guided wavelength at the cut-off frequency. The filter structure is simple and easy to fabricate as well

A Miniaturized wide Stopband Low-pass Filter using T and Modified L Shapes Resonators

A new structure of microstrip-based low-pass filter with wide stopband and sharp roll-off is introduced, in this paper. In the proposed topology, resonators with T and modified L Shapes have been used. To improve the suppression factor and relative stopband bandwidth, the second resonator has been added to the first resonator. The designed filter has been fabricated on a 20 mm thickness RO4003 substrate, which has a loss tangent of 0.0021 and a relative dielectric constant equal to 3.38. All parameters including roll of rate, stopband, bandwidth, return loss, insertion loss, and figure of merit have significant coefficients. Simulation has been ran using advanced design system software. The 3dB cutoff frequency is appropriate. The value of the insertion loss parameter is <0.1 dB and the S11 parameter is −22 dB at this point. The stopband is extended from 2.42 up to 24 GHz, which shows an ultra-stopband. The results of the simulation and experiment are almost similar, which indicates a proper performance of the designed structure