6 - 18 GHz Edge Mode Isolator

A stripline geometry with high permeability pole pieces in contact with the upper and lower ground planes minimized the magnetic internal field non-uniformity that can degrade performance at low frequencies. A commercially available ferrite with 4piM=3440 gauss gave optimum isolator performance. YIG sections at the input and output with 4piM=1780 gauss minimized low frequency loss due to excitation of magnetostatic waves. The calculated S₁₂ was ~ldB from 4GHz to 20GHz with S₂₁ exceeding -20dB from 6GHz to 17GHz. Measured S₂₁, was >-3dB from 7GHz to 19GHz. S₁₂, was <-10dB from 6GHz to 20GHz.