A new ceramic-to-metal RF feedthrough reduces power loss from electromagnetic coupling. The single- and dual-conductor RF feedthroughs have a frequency range of 100 kHz to 13.56 MHz and a temperature range of -55°C to 400°C. They handle currents up to 800A and voltages up to 14 kV. Standard feedthroughs are available as weldable and vacuum flange-mounted units. Also available are feedthroughs with custom coolant flow paths and with solid conductors on the vacuum side.