Design of a Novel Ultrawide Stopband Lowpass Filter Using a DMS-DGS Technique for Radar Applications

Abstract

A novel wide stopband (WSB) low pass filter based on combination of defected ground structure (DGS), defected microstrip structure (DMS), and compensated microstrip capacitors is proposed. Their excellent defected characteristics are verified through simulation and measurements. Additionally to a sharp cutoff, the structure exhibits simple design and fabrication, very low insertion loss in the pass band of 0.3 dB and it achieves a wide rejection bandwidth with overall 20 dB attenuation from 1.5 GHz up to 8.3 GHz. The compact low pass structure occupies an area of (0.40λg × 0.24λg) where λg = 148 mm is the waveguide length at the cut-off frequency 1.1 GHz. Comparison between measured and simulated results confirms the validity of the proposed method. Such filter topologies are utilized in many areas of communications systems and microwave technology because of their several benefits such as small losses, wide reject band, and high compactness.

Design of Compact Reconfigurable Broadband Band-Stop Filter Based on a Low-Pass Filter Using Half Circle DGS Resonator and Multi-Layer Technique

“…Further, various methods of wide banding have been devised for various functions. For this aim, different techniques have been proposed, such as cascaded resonators [4][5][6], step impedance resonators (SIRs) [7], microstrip ground structure (DMS) [8,9] and defected ground structures (DGS) [10][11][12][13][14][15][16]. All of these techniques have some boundaries on the minimization of structure sizes, because they are based on half-wave resonators.…”

“…On the other hand, reducing the size of the slot would improve the return loss while degrading the stopband characteristics. In order to simultaneously improve the passband and stopband performance of the DGS microstrip structures, some efforts have been reported in [10][11][12]22]. However, the problem of DGS microstrip structure with good performance in both the passband and stopband was not fully solved.…”

Design of Low-Pass Filter Using Meander Inductor and U-Form Hi-Lo Topology With High Compactness Factor for L-Band Applications

“…The designs of low-pass filter topologies [1][2][3] with suppression of unwanted harmonics, sharp roll-off, ultrawide passband, low insertion loss, large rejection band, low fabrication tolerance and small occupied area are highly recommended for microwave circuits and modern telecommunication systems. Over these years, microstrip planar low-pass filters have been widely proposed as an approach solution to solve the most difficult technical challenges in microwave and wireless communication areas.…”

“…Over these years, microstrip planar low-pass filters have been widely proposed as an approach solution to solve the most difficult technical challenges in microwave and wireless communication areas. One of the techniques that can be applied to planar LPF is employing a cascaded method in which the resonators are placed vertically or horizontally side by side [4][5][6][7][8][9][10]. The disadvantages of using this procedure appear in filter size and insertion loss, which not completely achieve the requirements of communication systems.…”

“…However, in both proposed topologies, the disadvantages of large circuit size and presence of inaccurate results remain real challenge. In [8,19], the candidated LPF employs defected microstrip structure (DMS) technique. DMS is achieved by etching uniform or nonuniform slit on the signal strip, and it exhibits the same frequency behavior as DGS.…”