Compact microstrip low‐pass filtering power divider with wide harmonic suppression

Abstract

A compact, low-cost Wilkinson power divider (WPD) of 1.3 GHz (f 0 ) operating frequency, with a low-pass filtering response, is presented in this study. Power division and low-pass filtering responses are both achieved by using two symmetrical units of interdigital line resonators (ILRs). Each square unit of ILR exhibits a low-pass filtering response, with a minimum insertion loss of 0.3 dB. The dumbbell-shaped, defected ground structures are introduced for widening the attenuation band by suppressing the harmonics up to 14 GHz (up to 10.76 f 0 ) and also for miniaturising the circuit. An isolation resistor of 100 Ω is placed between two output ports of the WPD for obtaining good isolation. The operating frequency of the low-pass filter is 2 GHz with an attenuation of -17 dB up to 20 GHz. The proposed structure is fabricated using low-cost substrate material FR4. Both the low-pass filter and the power divider are fabricated and measured. The electromagnetic-simulated and measurement results are experimentally verified.