Free standing portable HF vertical

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Build an HF vertical that doesn't require trees based on a large telescoping whip, loading coil, tripod, ground plane. This should be a super-portable, multiband antenna with elevated radials. The whip alone will be capable of 20M-6M, and the coil will add 40M and 30M.

Project lead: Ryan (NY2O)

Bill of Materials[edit]

Materials (WIP)
Item Qty Needed Price/unit Link Notes
Metal Whip 1 $5.60* Aliexpress Available for individual purchase and faster shipping here
Screw-Mount Nut (M10) 2 $0.62 Amazon Min. purchase 12
M10-1.5mm Hex Nuts 2 $0.25 [https://a.co/d/baQ9Sog Amazon Min. purchase 40
Threaded Rod 1 $1.07 Amazon Min. purchase 8
SO-239 Panel Mount 1 $1.98 Amazon Min. purchase 4

*Prices marked with an asterisk may be lower if items are purchased in bulk. All prices are for individual items.

Additional Parts[edit]

  • 3d printed stuff?
  • radials

Coil Specifications[edit]

Based on some calculations from this calculator by K7MEM, here are some preliminary design specs for our coil. This calculator deliberately returns values that are slightly overlength to allow for easy tuning.

Assumptions[edit]

  • Wire: 18AWG Enameled
  • Form: 1" PVC (OD 1-5/16")
  • Target Frequency: 7.2MHz
  • Radiator Length: ~220" (5.6M)
  • Radiator Diameter: 0.125" (est. average)

Output Values[edit]

  • Target Inductance: 9.258 µH
  • Coil Length: 0-3/4"
  • Coil Turns: 16.5
  • Turns Spacing: 0-3/64"
  • L/D Ratio: ~0.57:1

Design Ideas[edit]

Section Breakdown[edit]

  • Radiator
    • Telescoping whip. 5.6M at full extension, connects with M10 thread.
  • Coil
    • Loading coil that screws in between the radiator and feedpoint.
    • Built around a 1" PVC pipe with flat caps. M10 male on one side, female on other side, connected to the ends of the coil.
    • Will use 3D-printed comb spacers to align coils.
    • Will load the antenna to 40M at full extension, and 30M if shortened.
    • Approximate inductance: 9.3µH (based on estimated values)
  • Feedpoint
    • 2" PVC pipe with flat caps. SO-239 connection on the side.
    • Two banana jacks on underside to connect radials.
    • M10 female thread at top to accept coil or radiator.
    • Main attachment point to tripod. Attached with U-clamp. (permanent or removable for storage?)
  • Radials
    • Segmented radials that connect together to reach the length for the desired band
    • Each segment adds the length needed for the desired band when combined with all previous ones
      • e.g. for 15M, connect segments for 6M + 10M + 12M + 15M
    • Connect with powerpole? Banana?
    • Two radials for main bands, can combine into one radial for 40M (or we could add long extra segments to allow 40M with dual radials)
    • Radials can be arranged 90deg apart and aimed for a bit of directionality (POTA PERformer guide claims ~4-8dB front-to-back ratio)
    • Each radial also has one non-conductive connector so the length is always the same and the radial ends don't need to be re-staked or moved when changing bands
      • e.g. for the 15M example: 6M + 10M + 12M + 15M + (dummy segment) + 20M
    • See the POTA PERformer build guide for more info
  • Tripod
    • Basic off-the-shelf photography tripod
    • Weights for support
      • rice socks?

Other Ideas[edit]

  • ground plane
    • banana plugs or power poles to connect ground plane?
    • segmented ground plane (with rope physical linkage) or fan dipole style ground plane
  • tripod?
  • balun/unun?
  • feed point insulator and mechanical support

External links[edit]

Retrieved from "http://newton.i2lab.ucf.edu/w/index.php?title=Free_standing_portable_HF_vertical&oldid=19082"