Dual-Band Tunable Microwave Bandpass Filter Using Stepped Impedance Technique

This paper is focused on designing a bandpass filter at microwave bands that uses alternating very high and very low characteristic impedance microstrip transmission lines and can be electronically tuned by using a hyper-abrupt junction varactor to shift the center frequency. intending to present a Dual-Band Tunable microwave bandpass filter to be used in WIFI, Bluetooth, GSM, and other antennas applications. The filter is a maximally flat third order filter, implemented using a stepped impedance method. The first band is tuned between 1. 75-2.66 GHz with an average bandwidth of 160 MHz, and the second band covers the range between 3.85-4.54 GHz with an average bandwidth of 70 MHz.