A method for coupling high-frequency energy, in particular for microwave circuits, to a nanoscale junction involves placing a bias-T outside of the tip and sample circuits of a scanning probe microscope and connecting a portion of a sample of analyzed semi-conductor through an outer shielding layer of coaxial cable so as to complete a circuit with minimal involvement of the sample. The bias-T branches into high and low-frequency circuits, both of which are completed and, at least the high-frequency circuit, does not rely on grounding of implements or other structure to accomplish said completion.