Georgia Journal of Science

Article Title

Microstrip Based Butterworth Low Pass Filter


In RF/microwave and wireless communications, compact size of passive circuits such filters is essential. We have designed a microstrip structure based low pass butterworth filter suitable for RF/microwave applications using a free Electro-Magnetic (EM) simulator, Sonnet Lite. Filter design and EM simulation both were performed using Sonnet Lite, which employs the Method of Moments (MOM) to solve Maxwell’s equations and generates scattering matrix elements such as S11 and S21. The filter design was implemented on a microstrip patch with an area of 32x 16 mm2. Our constructed low pass filter design yielded an attenuation of -18dB at 5GHz by using FR4 substrate material available in Printed Circuit Boards (PCB) as dielectric layer with a dielectric constant of 4.4. The low pass filter response was measured using a Vector Network Analyzer (VNA), the filter response shows the cut-off frequency around -3dB occurs at 3.26 GHz in S21. Our measured values of S21 closely matches to the simulated values of S21 over a wide range of frequency. Such compact and low-cost design is ideal for use in the field of wireless communication or microwave band of frequencies.

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