Wideband 18–40 GHz Surface Micromachined Branchline Quadrature Hybrid

This letter demonstrates two 18-40 GHz rectangular coaxial branchline quadrature hybrids designed using circuit and full-wave simulations. The chosen topologies are fabricated in a surface micromachining technology PolyStrata. Measured in-band performance of baseline wideband branchline hybrid shows |S₁₁|<;-10dB, |S₂₁| = -4.1 ± 1dB, and |S₃₁| = -4.3 ± 0.7 dB. This hybrid is miniaturized by meandering the rectangular coaxial lines to obtain 57% reduction in surface area and in-band performance with |S₁₁| <; -10dB, |S₂₁|= -4.2±1.2dB, and |S₃₁| = -4.1 ± 0.7 dB.