EA1HET

POTA antenna setups

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My POTA activities predominantly makes use of Chamelon Antenna equipment for quick deployment and operation.

While planing to go POTA, or even SOTA, several antenna related details should be clarified in advance, like the type of antenna to deploy based upon the bands to work on and/or the type of wiring to be carried.

I tried to make a quick resume of my research, that follows now. Please, be indulgent if you already tried this with better success than me, and share your knowledge if you want to. Thank you.

Wiring sizes (awg to mm2)

  • 26 awg = 0.14 mm2
  • 24 awg = 0.20 mm2
  • 22 awg = 0.32 mm2
  • 20 awg = 0.51 mm2
  • 18 awg = 0.80 mm2
  • 16 awg = 1.30 mm2
  • 14 awg = 2.00 mm2
  • 12 awg = 3.31 mm2

CHA SS25 (25ft) whip rod setups:

  • For 80m: TBD – Needs more field testing.
  • For 60m: Rybakov, WRSB.
  • For 40m: λ/4 Vertical, WRSB, Rybakov.
  • For 30m: TBD – Needs more field testing.
  • For 20m: λ/4 Vertical, WRSB, Rybakov, POTA Dominator.
  • For 17m: TBD – Needs more field testing.
  • For 15m: TBD – Needs more field testing.
  • For 12m: TBD – Needs more field testing.
  • For 10m: TBD – Needs more field testing.

λ/4 Vertical radiator:

  • Note(s): None
  • Per band tuning:
    • For 40m: fully extended with 40M-Coil.
    • For 30m: TBD – Needs more field testing.
    • For 20m: 8 1/2 sections + radials.
    • For 17m: TBD – Needs more field testing.
    • For 15m: TBD – Needs more field testing.
    • For 12m: TBD – Needs more field testing.
    • For 10m: TBD – Needs more field testing.
  • SWR Readings on GPS coordinate:
    • TBD
  • Bands:
    • 10m to 20m:
      • Chameleon SS25 whip is 1/4 wave resonant vertical
      • 4x 16ft (5m) radials of 20 awg (0.51mm2) wire or large EMF blanket
      • Coax choke
      • Chameleon spike
    • 30m and 40m:
      • Same that “10m to 20m” plus coil (40M-Coil, Medium Coil)

Wolf River Silver Bullet (WRSB) 1000:

  • Note(s): this setup requires minor tuning. It’s often needed an ATU for 80m.
  • Bands:
    • 10m to 20m without coil:
      • Chameleon SS25 whip is 1/4 wave resonant vertical
      • 4x 16ft (5m) radials or large EMF blanket
      • Coax choke
    • 30m to 80m with coil:
      • Chameleon SS25 whip used with the adjustable WRSB coil
      • 4 x 16ft (5m) radials of 20 awg (0.51mm2) wire or large EMF blanket
      • Coax choke

Rigid Rybakov:

  • Bands:
    • 10m to 20m without additional components:
      • Resonant with whip partially/fully extended
      • LDG 4:1 UnUn (voltage balun) at the base of the antenna
      • Coax choke
      • 4x 16ft (5m) radials of 20 awg (0.51mm2) wire or large EMF blanket
    • 30m to 80m:
      • Same that “10m to 20m” plus:
        • 40M-Coil
        • Requires ATU

Rybakov Inverted “L” or “Lazy”:

  • Bands:
    • All bands:
      • SS25 whip fully extended (25ft, 7.6m)
      • LDG 4:1 UnUn at the base of the antenna
      • 4x 16ft (5m) radials of 20 awg (0.51mm2) wire or large EMF blanket
      • 28ft (8,53m) to 33ft (10.06m) of 22 awg (0.32mm2) wire wire from the tip of the whip to a tree or to ground
      • Requires ATU
      • Coax choke

POTA Dominator:

  • Bands:
    • 10m to 20m:
      • Tripod + Jaw clamp
      • Chameleon SS Insulator
      • Chameleon SS Puck Hub
      • Chameleon SS Blank Adapter
      • Chameleon SS25 whip rod tuned for 1/2 wave per band
      • Pigtail to match antenna length on 20m
      • 49:1 EFHW balun/transformer to match impedances at the base of the antenna
      • Coax choke
      • PVC pipe acting as support for a counterpoise
      • 1x/2x counterpoise tuned to frequency in use (see below)

Counterpoise(s)

Normal cables:   
    - 1x/2x of 34ft 20 awg tinned copper PTFE
    - 10,36 meters of 0,5 mm² wire

Stealth/HOA-friendly counterpoise option:
    - 1x 21ft (6,4m) counterpoise laying on the ground

Radial(s)

Band (Meters)   Frequency (MHz) Length (Feet)   Length (Meters)
10m             28.5            8.2 ft          2.50 m
12m             24.9            9.4 ft          2.86 m
15m             21.3            11 ft           3.35 m
17m             18.1            12.9 ft         3.93 m
20m             14.2            16.5 ft         5.03 m
30m             10.1            23.2 ft         7.07 m
40m             7.2             32.5 ft         10.0 m

For the radials, think of an implementation mode that could be modular and avoid having multiple unused cables in the backpack. A good implementation could be using Powerpoles to extend cables that match each band at a time while in use:

  • Base radial (2.5m / 8.2ft) → Covers 10m well.
  • Extension 1 (add 1m / 3.3ft) → Brings total to 3.5m / 11.5ft for 15m.
  • Extension 2 (add 1.5m / 4.9ft) → Brings total to 5m / 16.4ft for 20m.
  • Extension 3 (add 2.5m / 8.2ft) → Brings total to 7.5m / 24.6ft for 30m.
  • Extension 4 (add 2.5m / 8.2ft more) → Brings total to 10m / 32.8ft for 40m.

Why there aren’t cables for 12m and 17m?

Simply, because not worth it. Not worth adding intermediate cables for 12m & 17m as proposed cuts are already optimized for easy matching:

  • For 17m (18.1 MHz), the best λ/4 counterpoise would be 3.93m (12.9ft). The 3.5m (11.5ft) counterpoise (for 15m) is close enough to work, plus the 5m (16.4ft) counterpoise (for 20m) also works with an ATU adjustment.
  • For 12m (24.9 MHz), the best λ/4 counterpoise would be 2.86m (9.4ft). The 2.5m (8.2ft) base counterpoise (for 10m) is already very close and the 3.5m (11.5ft) counterpoise (for 15m) is slightly long but still usable.

So my decision is to let the ATU handle minor mismatches; these bands are forgiving. And, if packing wires is not a constraint (like it’s in SOTA), radial field already might have multiple cables deployed with different lengths each, so, they will interact and provide coverage for intermediate bands like 12m & 17m.