Helical Antenna v5 Questions


#1

Hi I’m looking for some guidance in finding some of these parts:

  • 1 Pcs Aluminium (Square tubes profile 20x20mm) = 1600mm
  • 2 Pcs Aluminium (Symmetrical L profiles 15x15mm or 20x20mm) = 680mm
  • 2 Pcs Aluminium (Symmetrical L profiles 15x15mm or 20x20mm) = 420mm
  • 1 pc at least of 70Χ70cm good quality grid mesh of 2mm with at 1in (25,4 mm) spaces.

I haven’t had much luck with google searching, and was wondering if any of you who have successfully made this version of the helical can recommend a source for ordering metric size parts in America. I have tried a site called metric metals but they do not stock the L profiles. If theres any successful imperial measured substitution I am also open to that.

I have no luck whatsoever finding the grid mesh, and additionally, what type of metal should be used for it?

Also why is the antenna using brass as opposed to copper/aluminum. Sorry if these questions seem redundant.


#2

Hi, do you have a link to the design of helix you are trying to build? I would imagine if its VUHF then none of the dimensions are critical for the supporting metalwork, for example the 20mm box section could be substituted with 3/4" box. and the mesh really can be anything, use a bit of chicken wire with a supporting frame etc. For the helical element, again depending on the frequency, you could use 1/4-3/8 for VUHF or 1/8 if its L-Band etc, just use what you can easily lay your hands on. Helicals for VUHF are not at all critical, the b/w is something like -20% + 10% of centre freq, so there are usable tolerances.

regards,

Paul.