Synthesis Design of Unequal Filtering Power Divider With Ultra-Wide Matching Bandwidth and Large Isolation Bandwidth

Abstract

In this study, two novel topologies are proposed to synthesize a class of unequal power dividers with ultra-wide matching bandwidth, good filtering performance, and large isolation bandwidth. The filtering branches of the proposed power divider consist of a network and two impedance transformers. On the one hand, the network combines the impedance network jointly realize the Chebyshev transformer function. Therefore, the designed power divider terminated with three standard 50-Ω ports can be synthesized by the prescribed return loss (RL) bandwidth and power dividing ratio. On the other hand, the λ/4 lines in the network are inherently proportional property so that one/two isolation resistors can be introduced and calculated by equations to realize the wideband filtering power dividers with unequal power division and without loss. For demonstration, examples of 4:1 and 2:1 wideband filtering power dividers with RL bandwidth of 100% and 120% based on the two topologies are synthesized and simulated. Subsequently, the 2:1 wideband filtering power divider is fabricated and measured. The measured results exhibit the RL bandwidth is 121% (|S₁₁|<−14 dB), and large isolation bandwidth is 200% (|S₁₁|<−13.5 dB). Satisfactory agreement between the measured results and theoretical expectations is observed, verifying the validity of the proposed design concepts.