On Mon, Aug 17, 2020 at 09:29 AM, David Eckhardt wrote:
The intention of the following:
1) ALL TRANSMISSION LINE(s): Fields close onto themselves. The system is
self contained as far as the fields are concerned.
This is only true if the current on the transmission line has the same magnitude (but opposite directions) on the two conductors. If not the transmission line will radiate.
Take the case of a dipole (or doublet) , connected to ladder-line transmission line, where the two elements do not have the same impedance due to being different lengths or affected by nearby objects. The current imbalance will cause the feed-line to radiate. The same thing happens with coax where radiation will take place from the outer surface of the shield.
Roger
Roger Need