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.


#3

Hi Paul,

Thanks for the reply, sorry this is a late response. The link for the v5: https://ohai.satnogs.org/project/helical-antenna-v5/hardware/

We are currently building the v3.0 rotator first. Our goal is to download hi-res images from a CubeSat that we are developing alongside this. As you recommended, we modified our order to accommodate 3/4 boxes along with a much more readily available mesh. I did some research on my own and found that the brass wire shouldn’t impact the performance that much, and it is a safer choice for being out in the weather. Generally asking though, will this be able to do the job of downloading images (we will be using the 435Mhz freq)? We are a group of students, very new to this and RF in general, so we’re learning as we go.

Thank you,

Steve