Millimeter-Wave Power Combining Techniques

Millimetre-wave power combining is essential for applications ranging from high-data-rate wireless communications to radar and sensing. At these frequencies (30–300 GHz), individual amplifier or oscillator devices deliver limited output power, necessitating techniques for coherent combination. Corporate networks employ hierarchies of splitters and combiners in planar or waveguide form, offering precise amplitude and phase control but increasing insertion loss as stages multiply. Spatial combining merges separate radiated beams within quasi-optical or waveguide cavities, enabling high power density with reduced thermal stress but demanding exact beam alignment and mode purity. Hybrid approaches integrate planar circuits with waveguide magic-T or T-junction structures, balancing size and loss. Critical performance metrics include insertion loss, isolation between input ports, amplitude balance and phase balance. Recent advances focus on novel waveguide transitions, mode converters and additive-manufactured components to extend bandwidth, improve efficiency and simplify fabrication.

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Millimeter-Wave Power Combining Techniques publication trend

The graph below shows the total number of articles in millimeter-wave power combining techniques across all publications each year (not limited to Nature Index journals).

Technical terms

Spatial power combining: Technique that merges multiple radiated or guided waves directly within a waveguide or free-space cavity to increase output power density.

Corporate combining network: Hierarchical array of power dividers and combiners implemented in planar or waveguide form, offering precise amplitude and phase control at the expense of cumulative loss.

Insertion loss: The loss of signal power resulting from the insertion of a device in a transmission line, expressed in decibels.

Isolation: The measure of how well input ports are decoupled, indicating minimal mutual coupling or signal leakage between them.

Amplitude/Phase balance: The uniformity of output power levels (amplitude balance) and phase relationships (phase balance) across combined channels, critical for efficient coherent combining.

References

1. Ka-Band Tray-Type Spatial Power Combiner Using H-Plane Expanded Waveguide With Side-Ridges. IEEE Access (2023).
2. H-Plane Waveguide In-Phase Power Divider/Combiner With High Isolation Over the WR-3 Band. IEEE Access (2021).
3. Design of a 94 GHz Millimeter-Wave Four-Way Power Combiner Based on Circular Waveguide Structure. Electronics (2021).