Are there parabolic antennas that have reflectors made solely from copper tubing /
copper mesh? If not, why?

Copper and copper alloys are more costly, but not stronger than
aluminum and several other metals by weight or cost. Most people do
not find the blue-green corrosion attractive, but it probably degrades
performance no more than the corrosion on most other choices. Likely
someone makes copper parabolic antennas.   Neil

?neilzero? says it all. But why the interest -- perhaps you are
considering fabbing one yourself and you have lots of copper. If so
fine. Easy to bend, though much easier if annealed first but gets a
bit claggy to cut.

Or perhaps you suppose the high electrical conductivity should make a
better reflector? Doesn?t actually make much difference. In fact at
ultra high frequencies some non-conductors should work reasonably
well.

Best

Thanks Neilzero and Guzzi!  Guzzi, you hit the nail on the head, as I
am looking at making my own parabolic dish.  The choice of copper was
twofold- I assumed it would be the best reflector given its
conductivity properties, and I have worked with copper tubing on other
projects.  The parabolic antenna would be used at a range of
frequencies, from 900mhz upwards of 5.8 ghz (by creating multiple
interchangeable feeds).

However, if aluminum work work just as well, I might go that route. 
Any thoughts on this or using galvanized steel?  Mesh vs. solid
reflector?  I am also happy to pay for these answers :-)

JR

Mmmm, build your own. Good on you. Some interesting links below, some
with links to design stuff. Lots of other fine stuff too, but I think
that?s enough to digest in the meantime :-)

http://www.seattlewireless.net/pipermail/talk/2004-August/005854.html

http://www.mlesat.com/Article1.html

http://www.freeantennas.com/

http://www.newwaveinstruments.com/resources/rf_microwave_resources/sections/antenna_tutorial_theory_design_software.htm

http://www.msdist.co.uk/th/en/products/mesh.phtml

http://www.afrts.osd.mil/tech_info/handbook/pdf/section05.pdf

I was going to suggest mesh size of maximum of 1/8 wavelength but the
last link says 1/10, so 900 megs would be 3.3 cm max, and 5.8 gigs
would be 0.5cm -- obviously you?d have to go for a max of 0.5 cm.
Reason for using mesh rather than solid is for weight and wind
resistance. For rigidity, the mesh can be mounted on a solid framework
of wood, metal, concrete, etc. For absolute precision, solid is better
because it blocks *all* interference and reflects more precisely but
you?re not building a radio telescope are you?

Factors of efficiency, diffraction, and gain seem to be covered well.
Not so much on mesh materials but anything (metallic) which you can
form accurately will be fine. Ally foil on a fibre glass base is good,
or even nickel coating spray. Some people have used zinc mesh, the
stuff used as a base for fillers in car repair. It works dead easy and
solders well -- not to be confused with zinc castings which usually
contain aluminium and don?t solder easily. Aluminium would be fine but
difficult to bond to. Nothing wrong with galvanised steel if it?s
reasonably smooth. There?s stuff on surface accuracy in the links. Bit
difficult to hammer into shape though and welding is not recommended
without an air supply mask. And of course for 900 megs it?ll have to
be pretty big and heavy to be useful. I suppose too that carbon fibre
could be used -- and found this site !!!!

http://www.broom.engineering.btinternet.co.uk/heathcliff1.htm

But more seriously, this search :-

://www.google.com/search?hl=en&lr=&q=%22carbon+fiber+parabolic%22&btnG=Search

As you will see from the other links, there are simple quasi parabolic
designs which are only parabolic in one plane, a design beloved of
school projects using chicken mesh. Or even corner reflectors. But
your frequencies are a bit higher and those ones can only feed a
dipole, or dipoles if longer and spaced well apart. Can?t remember the
impedance effect off-hand. But you?re wanting to use interchangeable
feeds so that?s out anyway. Feeds are tricky of course but that?s your
problem :-) You may be aware of arrays as an alternative to a
parabolic dish. Easy(ish) to build but a bit cumbersome and quite
narrow band.

Is this enough to be going on with? More if you want it.

Don?t worry about paying -- I?m not a ?researcher? so no way anyway.
My pleasure -- but an impecunious authoritative researcher may pick up
on this.

Best