Hi Mike,

It has been years and years since I had to deal with "loss of a typical BNC connection" but these URL's may help answer your questions.

http://www.amphenolrf.com/products/slimlinebnc.asp

Electrical
Impedance	75 Ω with acceptable return loss up through 1 GHz
VSWR	1.10 max up to 750 MHz (Return Loss -26.44 dB ) 1.16 max up to 1 GHz (Return Loss -22.61 dB) MIL-STD-1344, method 3005
Working Voltage	400 VAC, peak
Dielectric Withstanding Voltage	1000 VAC at 5 seconds minimum per MIL-STD-1344, method 3001, test condition I
Contact Resistance	Center contact: 12 m Ω initial, 12 m Ω after environmental, per MIL-STD-202, method 307
Insulation Resistance	› 1,000 MΩ @ 500 volts per MIL-STD-1344, method 3003
Insertion Loss	0.1 dB maximum up to 1 GHz per MIL-C-39012

Go to here for some technical info.
http://www.astronwireless.com/rf_coax.html

Here is another called "rf Made Simple":
http://www.amphenolrf.com/rf_made_simple/techquestions.asp

Warm regards,

Gary

FXE (Fort Lauderdale Executive)
http://www.uslan.com/hinge-kit.html