Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx> Hi Antonio, At 01:21 PM 11/26/2005, you wrote:
....The 30 kV/cm figure for initial breakdown is valid for at least 300 MHz. (At least, this is what my "Reference Data for Radio Engineers" says.) Antonio Carlos M. de Queiroz
Interesting!! We always worry so much about high voltage RF breakdown distances. RF tends to arc rather easily compared to DC.
However, "capacitive" leakage current is probably the real problem. If we have say 100kV at 100MHz and there is just 0.1pF of capacitance to ground, the current is:
100000 x 2 x pi x 1e8 x 1e-13 = 6.2 amps!!!! That will easily burn though any insulation!!
Good insulators at say 1e10 ohms will leak only 10uA at DC, but if you start oscillating the voltage, the leakage currents can get bad very quickly.
So I guess we should not worry so much about RF breakdown voltages, but should rather be concerned with high voltage RF capacitive leakage currents....
Cheers,
Terry