Fractal-shaped microstrip coupled-line bandpass filters for suppression of second harmonic

Author

Kim, IlKwon ; Kingsley, Nickolas ; Morton, Matt ; Bairavasubramanian, Ramanan ; Papapolymerou, John ; Tentzeris, Manos M. ; Yook, Jong-Gwan

Author_Institution

Dept. of Electr. & Electron. Eng., Yonsei Univ., Seoul, South Korea

Volume

53

Issue

9

fYear

2005

Firstpage

2943

Lastpage

2948

Abstract

In this paper, microstrip coupled-line bandpass filters using a Koch fractal shape are proposed for the first time. These filters are fabricated on a liquid crystal polymer (LCP) substrate for Ku-band. Conventional microstrip coupled-line filters are very popular for RF front ends because they can be fabricated easily. However, their large second harmonic causes the shape of the passband to be asymmetric in the upper band and it worsens the skirt properties. By proper design, the second harmonic of fractal filters can be significantly suppressed through the use of fractal shapes. In this paper, using LCP, the maximum harmonic suppression was almost 42 dB. This type of filter can be used to suppress the second harmonic without any additional devices and regardless of the substrate.

Keywords

band-pass filters; fractals; harmonics suppression; microstrip filters; Koch fractal shape; LCP substrate; fractal filters; liquid crystal polymer; microstrip coupled-line bandpass filter; second harmonic suppression; skirt property; Band pass filters; Fractals; Geometry; Harmonics suppression; Liquid crystal polymers; Microstrip filters; Microwave antennas; Passband; Power harmonic filters; Shape; Fractal-shaped bandpass microstrip coupled line filter; Koch fractal geometry; liquid crystal polymer (LCP); second harmonic suppression;

fLanguage

English

Journal_Title

Microwave Theory and Techniques, IEEE Transactions on

Publisher

ieee

ISSN

0018-9480

Type

jour

DOI

10.1109/TMTT.2005.854263

Filename

1505019