Integrated Micro-Coaxial Passive Components for Millimeter-Wave Antenna Front Ends

K. Vanhille, M. Lukic, S. Rondineau, D. Filipovic, and Z. Popovic (USA)


Coaxial cables, millimetre-waves, directional coupler, low loss, microfabrication, wafer-scale integration.


Miniature 250 to 700-μm tall copper air-filled rectangular coaxial line with inner conductor supported by periodic dielectric straps is demonstrated. The measured loss is as low as 0.08dB/cm at 37GHz, while the isolation between two parallel lines with center-to-center separation of 350μm is better than 60dB. A number of quasi-planar components are designed to be fabricated on the same 6 inch wafer using a sequential micro-fabrication process with 5 to 10 layers of copper. This paper presents an overview of several components that have been demonstrated in the air-micro-coax technology: low-loss densely-packed lines with a range of characteristic impedances; patch-type antenna elements; branch-line hybrids; cavity resonators; a Buttler matrix beamforming network. In addition to these components, the paper also discusses dividers/combiners and broadband hybrids, with an overview of the limitations and advantages of the technology.

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