期刊名称:International Journal on Electrical Engineering and Informatics
印刷版ISSN:2085-6830
出版年度:2011
卷号:3
期号:1
出版社:School of Electrical Engineering and Informatics
摘要:The modern microwave and millimeter wave communication system demands good filtering characteristics with compact sizes. In this paper the attention has been given towards the design of a good elliptical lowpass filter with sharp transition between passband and stopband, negligible passband insertion loss and wide stop band. A new defected ground structure (DGS) consisting of two square slots connects with a rectangular slot by two thin transverse slots underneath a microstrip line is proposed. In the frequency characteristics of proposed unit pattern provides an attenuation zero close to an attenuation pole. As a result, better transition sharpness, lower passband insertion loss and broader stopband are observed compares to dumbbell DGS. An equivalent lumped L-C network is proposed to model the introduced DGS unit and corresponding L-C parameters are extracted. A 3rd order quasi-elliptic lowpass filter with 1.4 GHz cut- off frequency, 1.7 GHz attenuation pole frequency, negligible passband insertion loss, almost 100 dB/GHz sharpness factor and 1.56GHz passband bandwidth (at -15 dB) is designed by cascading three investigated DGS units of different dimensions under capacitively loaded microstrip line.