Microstrip Dual-Band Bandpass Filter Using Stepped Impedance Resonators and Radial Stub

In this paper, design, fabrication and experimental results of a dual-band bandpass filter for global system for mobile communications (GSM) in center frequency f_1=1. 84GHz and worldwide interoperability for microwave access (WiMAX) in center frequency f_2=3. 5GHz are presented. The proposed dual-band filter for use in a simultaneous dual-band Power Amplifier is harmonically designed. Since, the second until fifth harmonics in the power amplifier output power and efficiency will play an important role size, good removal of these harmonics is important. Many multiband filters and circuits designed none have done to eliminate harmonic precision. The proposed dual-band bandpass filter configuration comprises of dual quad-section stepped impedance resonators with a J-inverter in between. With a combination of two bandpass and special Bandstop filters, accurately and completely remove all the harmonics. Ideal circuit components are provided with the relevant formula. After filter design, simulation and fabrication and the results of the internal characteristics both bands is measured.