GRD Journals- Global Research and Development Journal for Engineering | Volume 3 | Issue 6 | May 2018 ISSN: 2455-5703
Comparative Analysis of Stepped Impedance with Open and Short Circuited Stub Microstrip Low Pass Fractal Filter Ranjeet Kumar Department of Electronics & Communication Engineering Maharana Pratap College of Technology, Gwalior
Pankaj Singh Tomar Department of Electronics & Communication Engineering Maharana Pratap College of Technology, Gwalior
Abstract This paper proposed a comparison of stepped impedance fractal low pass filters at 1 GHz with open stub and short-circuited stub. Sierpinski carpet fractals used to reduce filter size and develop low profile filters. Fractal elements or arrays are designed with the concept of self-similarity to achieve sharper cut off point. 1 GHz low pass filter is used for long range communication and smart phone communication for IOT application. Keywords- Fractal, Chebyshev Response, Stepped Impedance Low Pass Filter, Open Circuited Stub, Short Circuited Stub
I. INTRODUCTION Filters play significant roles in many RF/microwave applications. Filters are used to select or detain the RF/microwave signals within assigned spectral limits. They are used to separate or combine different frequencies. In current scenario of wireless communication filter require higher performance, smaller size, lighter weight, and lower cost. To achieve these requirements, we design a Sierpinski carpet [1-2] fractal filter. The general form of low pass filter may consist of series inductors and capacitor which is frequently found in many applications for direct current or to block the dc. In design and realization of microstrip filters, short section of transmission line or stub, whose length is much smaller than a quarter of guided wavelength are the most common components [3]. A small open circuited loss less microstrip line stub is equivalent to shunt capacitor and similarly small shortcircuited line is equivalent to shunt inductor [4]-[7]. For a more selective low pass filter, more of such elements are required. The element values for the low pass prototype shown in figure 1 with Chebyshev response at pass band ripple factor LAR= 0.1 dB, characteristic impedance Zo = 50Ω, are taken from normalized values gi i.e. g1, g2, g3, g4…… gn. The components L & C are realized by high and low impedance microstrip stub respectively. The values of different inductance Li and capacitance Ci are obtained from the design equations, as Li = (Zo/go) (2c/2πfc) g1 (1) Ci = (go/Zo) (2c/2πfc) g2 (2)
Fig. 1: Prototype of low pass filter
Fig. 2: Microstrip stepped impedance low pass filter
For width calculation microstrip for inductance
All rights reserved by www.grdjournals.com
67