Wow, I'm amazed you put Teflon and nylon in the same category! There
are many types of nylon, and AFAIK, none is particularly low loss.

One reference I have suggests a dissipation factor for polymethyl
methacrylate (unadulterated "Perspex") of about .008 at 3GHz. Nylon 66
(a common formulation) seems to be about three or four times that much.
But beware that you commonly don't get "pure" plastics.

For comparison, Teflon runs more like .00015 dissipation factor at
3GHz. Pure forms of polyethylene and polystyrene are similarly low.
Polypropylene tends to be good, below .001. Polycarbonate is decent at
around .002.

Cheers,
Tom


Risto Tiilikainen wrote:
Martyn Preston kirjoitti:
Does anyone know how lossy perspex is at 2.3GHz? Want to use it to support a
helical antenna.

TIA - G0THY


Hi

I wouldn't try perspex nowadays
Perspex itself is very lossy when compared to modern compounds
I think perspex absorbs easily humidity and then you may have problems.
Specially in voltage maximum points of helical.
For the same reason I don't recommend fiberglass for outdoor use.

I recommend Teflon or nylon for insulators and supports.

73, Risto OH2BT