Low-Loss Millimeter-Wave Surface-Mounted Wideband Filtering Power Divider Based on MEFAB Process

This article presents the design of rectangular microcoaxial line (RμCL) wideband filtering Wilkinson power divider (WPD) using Micro-structure Electrochemical Fabrication (MEFAB) process. Firstly, a two-stage RμCL Wilkinson power divider is introduced as a foundation, operating from 11.95 to 43.6 GHz with a fractional bandwidth (FBW) of 113.9%, a minimum insertion loss (IL) of 0.8 dB, isolation better than 15 dB, amplitude and phase imbalances below ±0.38 dB and ±3°, respectively, and a circuit size of 0.69λ₀ × 0.34λ₀, where λ₀ is the free-space wavelength at 29 GHz. On this basis, an 18-40 GHz RμCL wideband filtering WPD is further designed by using stepped-impedance stub loaded coupled-line resonator (SIS-L-CLR) replacing the first stage of the above designed WPD. Design equations for the filtering configuration are systematically derived through even-odd mode analysis, with theoretical predictions verified by electromagnetic simulations. The fabricated RμCL filtering power divider achieves an operating band of 17.95–41.05 GHz, a FBW of 78.3%, a minimum IL of 0.9 dB, isolation better than 15 dB, amplitude imbalance under 0.19 dB, phase imbalance below 3.4°, and a compact circuit size of 1.18λ₀ × 0.4λ₀.