I am working with some coaxial connectors. I would like to get a better handle on maximum voltage. I have consulted 3 sources from Microwaves101 to Pozar but cannot recreate or support lab results with theory. To start, we know the voltage is limited by the coax section where the inner and outer conductor come into closest contact. This is the rear of the connector, outer conductor at dia. .048" (0.0012192m) and inner at .0210" (0.0005334m) with an air dielectric for the section. It's also known the electrostatic field in a coax is Epeak(r)=Vpeak/(r*ln(b/a)) where a is inner and b is outer radius, respectively. The maximum voltage for this coax is the voltage just before dielectric breakdown, in this case air, which we will take at 3MV/m, which happens at radius a. Therefore solve for Vpeak:
3000000 = V/( (0.0005334/2) * ln (0.0012192/0.0005334))
Vpeak= 661 V = 467Vrms.
The problem is the connector is rated for 670 Vrms. How could this be? I would say it is an error, but we had four devices tested by an outside lab and indeed they achieved 670 Vrms at 5MHz according to MIL-PRF-39012. Basic calculations do not support this.
3000000 = V/( (0.0005334/2) * ln (0.0012192/0.0005334))
Vpeak= 661 V = 467Vrms.
The problem is the connector is rated for 670 Vrms. How could this be? I would say it is an error, but we had four devices tested by an outside lab and indeed they achieved 670 Vrms at 5MHz according to MIL-PRF-39012. Basic calculations do not support this.