A Planar RF-LO Coupler Design for Heterodyne Receiver at 220 GHz

We present a design of a planar directional coupler comprising two different layers’ microstrip lines (MLs) at frequency of 220 GHz. The overlapping section allows the adjustment of the coupling efficiency between two MLs. This planar directional coupler for coupling the radio frequency (RF) and local oscillator signals can be integrated with mixer, which is highly desired for a compact receiver, especially constructing a large format multi-pixel array receiver at mm&sub-mm wave length. In this paper, its design and the plan for proof-of-concept will be discussed detailed.