A 215-GHz Radial Power Combination System With Multilayer and Contactless Structures

This paper presents a sub-millimeter wave radial power combination system with multilayer and contactless structures. The system is mainly composed of ${\text{T}}{{\text{E}}_{10}} - {\text{TE}}_{11}^{{\text{CP}}}$ (circular polarized TE11) mode converters, the radial power divider and combiner, waveguide-to-microstrip transitions, and eight power amplifier MMICs. The entire system is divided into multiple layers to facilitate passive and active power combination measurements. Furthermore, to simplify the assembly difficulty, and reduce unnecessary losses of waveguide splitting and interconnection, some contactless structures such as groove gap waveguides and waveguide chokes are designed and adopted. In the measurement, the passive radial power divider/combiner achieves a return loss of higher than 14 dB with an average insertion loss of 0.5 dB within 200-260 GHz, the eight-way combined active power amplification system delivers a maximum power of 23.3 dBm (212.4 mW) at 215 GHz. In the band of 207-223 GHz, the output power is higher than 100 mW.