Designed for mounting on the underside of an aircraft, providing excellent air-to-ground coverage. Bent configuration makes this antenna suitable for helicopters and low-wing aircraft."
They may be excellent for ground clearance but this aerial is a poor substitute for a proper vertical aerial. Amongst other things it will be strangely polarised, and the further you fold the aerial back on itself the more the terminating impedance will rise. Furthermore the adjacent steel tube of the airframe will become a part of the aerial system , strengthening the signal in one direction, reducing it in another, distorting the normal doughnut radiation pattern.
As for ground loops its not something you normally encounter in terminating aerial feeders. They are grounded at both ends, if not the impedance of the cable will alter and the outer screen will become part of the aerial itself. This fact is used sometimes to cheaply construct other types of aerials where precise lengths of inners and outers of co-ax cable are connected alternately together to make "co-linear" and other types of aerial.
A simple home aerial for VHF may be made by simply stripping back a piece of co-ax and folding back the braid back over the outside of the cable leaving the inner core as one half of a dipole and the braid as the other half with the whole thing effectivly being centre fed. The length of the braid and inner form the total lenght of the aerial and hence its frequency of operation. Often the whole thing may be put in a piece of plastic tube , filled with builders expanding foam and hey presto an outside aerial !
The comment earlier about top hat washers for headset sockets, normally applies just to the mic socket where you want isolation from airframe ground at the socket. The headset received audio socket is normally grounded at both ends. It is the mic input that has a high gain amplifier in the radio circuitry and the signals are in the millivolt range whereas the receive audio signals are 1000 times bigger and are less susceptible to interfering signals.
But as said before, good practice is the order of the day for all your radio and intercom wiring and is best left to someone experienced in this field as use of inapropriate cables or poor routing or grounding will give rise to problems.
Enjoy everything - Life is Short.