The Toroid Equivalent Circuit

The circuit used for the toroid itself is included below. R1, Rpre, & Rsh are all essentially zero, and are only there to make spice behave properly (they are decoupling resistors). RT is a 50 Ohm terminator, & ctloop is the measured capacitance between the test loop and ground ( 18pF -- the toroid response really isn't affected by this, but it was put in anyway). VL1 is a voltage source that is set to zero, making it possible to monitor the current in the "beam" loop. The values of ltor and ctor were determined by fitting a response function to the measured frequency response of each toroid. Lbeam and the coupling constant were scaled to make the amplitude in spice match the measured amplitude from each toroid.

In the real spice circuit, the toroid circuit was attached to the integrator by removing RT2 and VL2, and attaching node #8 to node #61 of the integrator.