A Low-Cost Compact Low-Pass Filtering Power Divider Based on Elliptic Function with Wide Attenuation Band

Abstract

A filtering power divider (FPD) with low-pass property and wideband harmonic suppression is presented in this paper. The microstrip structure of the FPD is designed based on elliptic function. The open stubs are embedded in the transmission line to obtain low-pass effect. An isolation resistor of 100Ω is connected between the two output ports to achieve good isolation. The operating frequency of the power divider is 2.9 GHz and the low-pass filter (LPF) has the cut-off frequency of 3 GHz with a sharpness factor of 55 dB/GHz. The attenuation band is extended up to 20 GHz (simulated) with a suppression of −19 dB. The maximum insertion loss in the passband for the FPD is −3.6 dB and the structure occupy an area of 0.7 × 0.21 . A lumped equivalent circuit of the LPF structure is also proposed. The LPF and the FPD both are fabricated using low-cost substrate FR4 of height (h) of 0.8 mm, a dielectric constant (εr ) of 4.4, conductor thickness (t) of 0.04 mm and loss tangent (δ) of 0.02. For experimental verification, the measured data are compared with the simulated ones.