16-Way Ka-Band Power Combiner Using Novel Waveguide Transitions

In this article, we present the design, manufacturing, and experimental validation of a Ka-band wide-bandwidth and low-loss 16-way combiner. We specifically focus on the analysis and demonstration of the combiner’s suitability for operation at millimeter-wave (mmW) frequencies. To that end, we extend the established radial-combiner design procedure. As part of this, we propose an oversized feeder design that allows for exceptional insertion and return loss. Furthermore, for the first time, we introduce a peripheral transition from the radial line to rectangular waveguide with integrated matching network and suitable schematic models. We also explore the design space of the radial line itself by analyzing the properties of various height tapers and, as a result, introduce an optimized radial-line profile that minimizes its reflections. The demonstrator measurements indicate an insertion loss (IL) of less than 0.24 dB, a return loss of better than 17 dB, and a phase imbalance of less than 3° in the entire Ka-band. To the best of the authors’ knowledge, this is the lowest IL for a wideband multiway combiner and at the same time one of the most broadband combiner solutions realized in the Ka-band.