Stub Resonator Tunable Bandpass and Lowpass Filters Using Shunt Stub Resonators

In microwave applications, filters are used to pass frequencies within a certain range(s), and rejects the other. The microwave bandpass filter at high frequencies above 0.3 GHz will be constructed using transmission lines instead of lumped elements due to the shorter wavelength. This project is intending to design a tunable microwave bandpass filter to be used in WIFI, Bluetooth and GSM applications, within the range of 1.85 GHz to 3.27 GHz with a maximum insertion loss of 1.14 dB, and a low pass filter with cutoff frequency varies from 0.61 GHz to 0.93 GHz. So, this filter is designed to work for these applications by changing the resonant frequency, using a varactor diode. The proposed filter is a maximally flat third order filter implemented using stubs.