By adjusting the value of the BST tuning capacitor
in relation to the monoblock's intrinsic capacitance, the optimum trade-off between frequency tuning range and insertion loss can be chosen.
Assuming the loop-tuning mechanism balances the inductive reactance of the loop itself with the capacitive reactance of the tuning capacitor, then the feedpoint impedance of the loop is the radiation resistance plus the loss resistance.
If the connections are kept to a minimum and well-made the main loss is in the tuning capacitor and in the skin-effect resistance of the loop material itself.
The team also issued a RFP for prototype high-current and high-voltage tuning capacitors
Automatic and manual modes with local and remote manual control of tuning capacitors