SMALL-SIZED MICROS TRIP LOWPASS FILTER USING DEFECTED GROUND STRUCTURE

• Main Author: SHAHRIN, MOHD FIRDAUS
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi PETRONAS 2009
• Subjects: TK Electrical engineering. Electronics Nuclear engineering
• Online Access: http://utpedia.utp.edu.my/7999/1/2009%20-%20Small-sized%20microstrip%20lowpass%20filter%20using%20defected%20ground%20structure.pdf; http://utpedia.utp.edu.my/7999/

Microstrip lowpass filter plays important role in many RF or microwave applications. They are used to select the microwave signals within assigned spectral limits. 1n this project, a conventional stepped-impedance microstrip lowpass filter is designed to have an equal-ripple response with a cutoff frequency of 0. 8 GHz. The filter needs to satisfy more than 20 dB insertion loss at 1.2 GHz with the impedance of 50 Ohm. By using the insertion loss method, filter performance is expected to be improved at the expense of a higher order filter. Another filter with the defected ground structure (DGS), having the same physical length, is introduced to investigate the performance of the filter. The simulation is carried out using the Agilent Advanced Design System (ADS) and Sonnet Suite software and in the experimental measurements a vector network analyzer is used. The results taken from the measurement shows that the signal response from the filter with DGS exhibits a wider passband frequency, with sharp cut off frequency. Another filter with defected microstrip structure (DMS) also shows the same behavior. The discontinuities structure proves that it can be used to improve the performance and reduces the size of the filter.