Build an Antenna for the Ground Station

I know nothink! I have no prior radio knowledge, but I’ve already taken care of the easy stuff - the rtl-sdr and the raspberry pi - so, it’s time to hunker down and learn some things.

Notes

Which Antenna?

  • Most SatNOGS make use of these types of antenna: yagi and helical
    • Helical polarization is circular
    • Yagi polarization is horizontal or vertical
    • Crossed-Yagi polarization is circular (and horizontal/vertical)
  • Satellite transmissions can be any of these polarities; hence the different antenna types
  • Signal loss when antenna/satellite polarities do not match:
    • Yagis lose about 20dB of signal
    • Helicals lose 3dB
    • Cross-Yagi loss is 3dB too
  • Helicals for 435MHz are a more reasonable size than a comprable Cross-Yagi
  • [References = SatNOGS members: planetsofa, g7kse, monroe, blackbird (see community)]

.:. I will build a Helical 435

The plan

  1. Find and Review Assembly instructions The SatNOGS Assembly page provides really nice step-by-step instructions with pictures.
  2. Print design files for the Helical Antenna v5
  3. Source the parts …Metal Supermarkets Phoenix
    • 1 Pcs Aluminium (Square tubes profile 20x20mm) = 1600mm
      • [20mm = 0.787in… 6 ft of 6063 Aluminum 3/4” square tubing]
    • 2 Pcs Aluminium (Symmetrical L profiles 15x15mm or 20x20mm) = 680mm
    • 2 Pcs Aluminium (Symmetrical L profiles 15x15mm or 20x20mm) = 420mm
      • [15mm = 0.59 in… 4 ft of 6063 Aluminum 1/2” square tubing or 4 more feet of the 3/4” tube]
    • 1 pc at least of 70Χ70cm good quality grid mesh of 2mm with at 1in (25,4 mm) spaces.
      • [at least 28”x28” of 1” x 1/8” Steel C1018 Mesh]
    • 11 pcs Acetal rods 8mm wide and 140mm long
      • [8mm = 0.31”, 140mm = 5.5”… 6’ of 3/8” plastic rod]
    • 22 Nylon nuts Μ8
      • [if we use 3/8” plastic rods, we need 3/8 nylon nuts instead of M8]
    • 1 N-Type connector
    • Brass wire 3mm approx. 6 m
    • Brass sheet 0.3 mm thick approx 20Χ10cm
  4. Take instructions, plans and parts into HeatSync Labs (local maker space) and see if they can help me. …I want to do it all myself, but I don’t have the tools.
  5. Test it.

Status

Step 3.

The build

References

Books