On 25 Mar, 06:44, wrote:
On Mar 25, 4:19 am, ml wrote:

hi

I've seen recently that some companies such as andrews etc are now
offering different coax and hardline with al outer shielding

they advertise lower cost, and lighter weight then copper , ok i get
that

but then they say the rf spec's are 'the same' so i ponder how do they
do that i would think copper would have better spec's ? obviously i
am missing something obvious

Skin effect means that the RF current is only being carried in a very,
very thin layer, so one can silver plate the inside of the aluminum
shield and the outside of the center conductor. At 100 MHz skin depth
for copper or silver is a bit more than 6 microns (0.25 mil), so it
doesn't take a very thick layer.

I had some 1/2" diameter stuff once that laid on the ground prior to
entering the house. A year or so later and the sheathing turned to
dust.
You may see some used for cable t.v. about 1 " diameter, these use air
as a dialectric and moisture can get in. All aluminum forms dislike
bending and easily kinks and do not straighten out easily. Personaly I
would avoid
aluminum for transmission lines.
Art