Calculates the attenuation, ’impedance’, reflection coefficient, VSWR and return loss of a circuit that incorporates a RF tank circuit into a Pi attenuator. Preferred resistor values are entered into the text boxes, similar to the way that values for a prototype may be selected. Values for the tank circuit may be selected with the Tank Circuit Resonant Frequency Calculator. A FLEXI-BOX is available with a dedicated PCB for this circuit and there is a selection of connectors. This is supplied as a kit, or as a ready built RF Trap With Attenuators.