POTA Field Antenna Reference // EN11xe

Central Nebraska · QRP CW 5W · Bands: 40 / 30 / 20 / 17 / 15 / 12 / 10m
Takeoff angle key: <20° = DX/skip · 20–45° = regional · >45° = NVIS/close
Rating: ●●●● Best · ●●●○ Good · ●●○○ Fair · ●○○○ Marginal
All data based on NEC2 consensus models, real-ground (EN11 silty loam ε≈13, σ≈0.005)
← wk0e.net
Band color key
40m 7 MHz 30m 10 MHz 20m 14 MHz 17m 18 MHz 15m 21 MHz 12m 24 MHz 10m 28 MHz
Antenna quick reference — all types
EFHW 66' (20.1m) Most versatile
BandWorks?Takeoff (inv-V)Takeoff (sloper)Notes
40m ●●●● 45–55°30–40° Primary NVIS/regional on inv-V; sloper adds DX
30m ●●●● 35–45°25–35° Resonant 3/2λ; excellent all configs
20m ●●●● 25–35°15–25° 2λ config; sloper really shines for DX
17m ●●●○ 20–30°15–20° Non-resonant; tuner needed; still effective
15m ●●●● 18–28°12–18° Resonant 5/2λ; low angle, great for runs
12m ●●●○ 15–22°10–15° Non-resonant; some tuners finicky
10m ●●●● 12–18°8–14° Resonant 4λ; multiple low-angle lobes
Key constraint: Transformer quality dominates performance. 0.5–1 dB loss baked in.
KXAT2 note: Will tune all bands with good transformer. Verify match each band change.
Random Wire (various lengths) Tuner required
Length40m30m20m15m10mAvoid?
29' (8.8m) ●●●○ ●●●● ●●●● ●●●○ ●●●○
35' (10.7m) ●●●● ●●●○ ●●●● ●●●● ●●●○
33' (10m) ●●○○ ●●○○ ●●○○ ●●○○ ●●○○ Avoid — ½λ on 20m, high Z
66' (20m) ●●○○ ●●○○ ●○○○ ●●○○ ●●○○ Avoid — ½λ on 40m too
Best lengths: 29' and 35' avoid resonance on all POTA bands.
Counterpoise: 17–20' on ground works well. Elevated 8–12' is 2–4 dB better.
Takeoff: 40–60° typical (NVIS-ish) — regional contacts to ~1000 miles.
Off-Center Fed Dipole Multi-band workhorse
BandRatingTakeoff (flat)Takeoff (inv-V)Notes
40m ●●●● 30–45°45–55° Near full-size dipole pattern
30m ●●○○ Not resonant; tuner required, variable
20m ●●●● 20–30°25–35° 2x half-wave; good DX angle
17m ●●○○ Non-harmonic; needs tuner
15m ●●●● 15–22°18–28° Harmonic of 40; strong performance
10m ●●●● 10–18°12–20° Harmonic of 40; excellent when open
Feed ratio: Classic is 1/3 · 2/3 split (133' total on 80m base; 66' total for 40m base).
Balun: 4:1 current balun at feedpoint — critical, don't skip it.
EN11 sweet spot: Flat at 30–40' with E–W orientation for N–S regional coverage on 40m.
17' Vertical Whip + Ground Screen Ground-dependent
BandRatingTakeoffDoor screenCHA FSR
40m ●●○○ 20–30° +2–3 dB vs bare gnd +2–3 dB vs bare gnd
30m ●●●○ 18–25° +2–3 dB +2–3 dB
20m ●●●● 15–22° +2–4 dB +2–4 dB
17m ●●●● 12–20° Best band Best band
15m ●●●● 10–18° +2–3 dB +2–3 dB
12m ●●●● 8–15° +2–3 dB +2–3 dB
10m ●●●● 7–12° +2–3 dB +2–3 dB
Door screen: Solid aluminum mesh, ~6×2.8 ft ≈ 17 sq ft — large continuous ground plane. Excellent performance, especially on higher bands where Fresnel zone is smaller.
CHA FSR: Two 20' conductive strips in X-pattern. <0.05Ω surface resistance. Comparable RF performance to door screen; see ground system comparison section below.
17' = ~¼λ on 20m: Natural resonance. On other bands, tuner handles it well.
EN11 note: Flat prairie ground is actually quite good for verticals — silty loam better than sand.
Rybakov 25' + 4:1 + CHA FSR Radials Best portable vertical for DX
BandRatingTakeoffNotes
40m ●●●○ 25–35° ~5/8λ at 40m; strong performer
30m ●●●● 18–25° Close to ideal electrical length
20m ●●●● 15–22° Excellent low-angle radiation
17m ●●●● 12–18° Strong — good DX potential
15m ●●●● 10–15° Best band on this antenna
10m ●●●○ 8–14° Very low angle; can be too sharp on closer contacts
25' ≈ 7.6m: Classic Rybakov length — intentionally non-resonant on all HF bands for broadband tuning.
CHA FSR radials: Surface resistance <0.05Ω copper-nickel fabric. Chameleon field tests show 23–28% field strength improvement over 4× 12.5' wire radials. Treat as equivalent to a solid 4-wire ground plane — not a compromise.
4:1 transformer: Must be a current balun (not voltage) for impedance transformation at the non-resonant feedpoint.
Bottom line: Best portable vertical option for 20–15m DX. 40m is strong. Deploy this when you want distance.
Inverted-L 40m specialist
BandRatingTakeoffNotes
40m ●●●● 20–35° Best portable 40m antenna you can build
30m ●●●○ 25–35° Works well with tuner
20m ●●●○ 20–30° Non-resonant; mixed pattern, still useful
15m+ ●●○○ variable Pattern gets complex; use with tuner, YMMV
Classic config: 33' vertical + 33' horizontal, fed at base. Single radial or ground stake enough for POTA.
Why it works: Vertical section provides low-angle radiation; horizontal section adds top-loading effect, slightly NVIS-ish.
EN11 sweet spot: This is your go-to if you have one tree and want 40m reach into the upper Midwest, Great Lakes, and East Coast pile-up callers.
Ground: Even a single 16' wire radial on ground is sufficient for 5W POTA work.
CHA Tactical Delta Loop No-tree option · 30m+ specialist
BandConfigRatingTakeoffNotes
40m Inv. delta ●●○○ 50–70° SWR 3.1–3.5:1 — tuner required; NVIS only
30m Inv. delta ●●●○ 25–40° SWR 2.4:1; tuner handles it; improving
20m Inv. delta ●●●● 18–30° SWR 2.1:1; full λ loop; best config for 20m
17m Inv. delta ●●●● 15–22° SWR 1.3:1; excellent — no tuner needed
15m Inv. delta ●●●● 12–20° SWR 1.8:1; strong low-angle performance
12m Inv. delta ●●●● 10–18° SWR 2.1:1; good DX angles
10m Inv. delta ●●●● 8–15° SWR 1.8:1; excellent when open
40m Vertical ●●●○ 20–30° Single whip + loop wire CP; SWR 3.0:1; tuner req.
20m Vertical ●●●● 15–22° SWR 1.4:1; omni, low angle — solid performer
What it is: Two 17' telescoping whips spread in a V, loop wire (25'4") clipped tip-to-tip forming a ground-level delta triangle. Hybrid Micro/Mini transformer at feedpoint.
Loop advantage: Full-wavelength loop on resonant bands gives ~2 dB over a dipole in theory, lower noise pickup than a vertical, bidirectional broadside pattern above 10 MHz.
Key limitation: Base sits at ground level — apex of the triangle is only ~8–10' up (where wire clips to whip tips). Chameleon notes elevation dramatically improves performance; requires their optional fiberglass mast.
40m reality: At this height the 40m loop is essentially NVIS only. Useful for short-skip contacts, not DX. The vertical config with loop-wire counterpoise is better for 40m low-angle.
No-tree park winner: Self-supporting, ~26' footprint, 5 min setup. When you have no trees and no mast this is your best option for 20–17m.
SWR data: From Chameleon's own measured table. KXAT2 handles 40/30m fine; 20m and up needs little or no tuning.
Vertical config: One whip + 25' loop wire as counterpoise — becomes your 17' vertical with a dedicated counterpoise. Good 20m+ performer, better 40m angle than the delta loop config.
JPC-12 Loaded Vertical (~13.5') Packability trade · 20m+ sweet spot
BandRatingTakeoffEfficiency notevs 17' whip
40m ●●○○ 20–30° Significant coil loss — ~3–6 dB penalty vs full ¼λ Worse — 17' is closer to full size
30m ●●●○ 18–25° Moderate coil loss — ~1–3 dB penalty Comparable to 17' whip
20m ●●●● 15–22° Near-resonant length — small coil penalty Roughly equal to 17' whip
17m ●●●● 12–20° Electrically long — good efficiency Similar or slightly better
15m ●●●● 10–18° Electrically long — minimal loss Similar or slightly better
12m ●●●● 8–15° Good efficiency at this length Comparable
10m ●●●● 7–12° Electrically long — use rod antenna only per manual Comparable
What it is: Loaded vertical — 4× black aluminum tubes (~51") + 2.5m stainless whip + sliding-contact induction coil. Total ~13.5' deployed. 1.4 kg, packs to 34.5 cm (~13.5"). Ground system: 10-strand wire mesh, use 3–4 strands.
Coil loading trade-off: Low SWR ≠ high efficiency on 40m. A well-matched short loaded antenna still has real coil ohmic loss. On 40m expect 3–6 dB below a full ¼λ vertical with good radials. On 20m and up the penalty is small and largely irrelevant at QRP levels.
Radial system matters: The included 10-strand mesh is the ground plane. 3–4 strands used per manual. Quality is unknown — treat as roughly equivalent to 3–4 short wire radials. Supplement with door screen or FSR if available.
Band change procedure: Adjust sliding shrapnel contact position on coil + retract/extend whip per reference table. Marked positions for 20m and 40m. SWR meter or KX2 built-in bridge needed to fine-tune. More fiddly than the 17' whip + KXAT2.
vs 17' whip: On 20m and up, performance is comparable. On 40m the 17' whip wins — it's ~½λ at 40m vs the JPC-12's heavily loaded ~⅛λ. The JPC-12's real advantage is pack size: 13.5" vs the 17' whip's 24" collapsed, and lighter overall.
EN11 POTA niche: Best justified as a weight/size-critical hike-in antenna when 20–17m are your target bands. For drive-up or weight-tolerant activations, the 17' whip + ground screen outperforms it on 40m and equals it everywhere else.
Ground system comparison — door screen vs CHA FSR vs wire radials
Context: For your 17' vertical and Rybakov, the ground system is at least as important as the antenna itself. These three options represent what you actually carry. The right choice depends on the park, not just RF performance.
🪟 Aluminum door screen (hardware store)
Size~17 sq ft (80"×36") — large ground plane
ConductivityAluminum mesh — excellent, very low loss
RF performanceBest of the three options
40m benefitStrong — large area helps at lower freq
20m+ benefitExcellent — Fresnel zone well covered
Packed sizeBulky — rolls up but awkward, ~36" tube
Weight~1–1.5 lbs — light but cumbersome
Setup timeFast — unroll, stake center, done
Tripping hazardModerate — low-profile but hard edge
DurabilityKinks and creases with repeated rolling
Cost~$15–20
Best for: Drive-up parks, car camping style activations, anywhere you're not hiking in. The RF performance is hard to beat for the price. The limitation is purely physical — it's awkward to pack and eventually the mesh fatigues and tears at the folds. For your 17' vertical specifically, the large continuous surface area is ideal.
⚡ CHA FSR (Chameleon Faraday Strip Radial)
SizeTwo 20' strips in X = ~40 linear ft, ~6 sq ft effective area
ConductivityCu-Ni fabric, <0.05Ω — very low loss
RF performance23–28% better than 4×12.5' wire radials (Chameleon field data)
vs door screenSlightly less total area — comparable in practice
40m benefitStrong — strip length extends electrical reach
20m+ benefitExcellent — strip width adds area near feedpoint
Packed sizeTwo 6×4" bundles — genuinely packable
Weight5 lbs total with hardware
Setup timeUnder 2 min — X pattern, stake ends
Tripping hazardLow — visible TAN color, soft edges
DurabilityCan be stepped on without damage
MPAS compatibleYes — 3/8-24 adapter included
Cost~$80–100
Best for: Hiking/backpacking activations, public parks where safety and visibility matter, and any deployment with the Rybakov/MPAS system where you want the integrated 3/8-24 mounting. The packability advantage over the door screen is real and significant.
🔌 Wire radials (reference baseline)
Typical config4× 12.5' or 2–4× 17–33' on ground
ConductivityWire — excellent conductor
RF performanceGood with 4+ radials; degrades fast with fewer
vs FSR4× 12.5' wires = 23–28% worse than FSR (field data)
vs door screenUsually worse unless many long radials
Packed sizeVery small — wind on a card or spool
WeightLightest option
Setup timeLonger — untangle, stake, repeat per radial
Tripping hazardHigh — nearly invisible, breakable
CostNear zero
Best for: Weight-critical deployments where every gram counts, or as a supplement to the FSR when you want to add radial count. On their own, four short wire radials are the weakest of the three options — the FSR and door screen both beat them on RF performance.
Head-to-head: door screen vs CHA FSR — which to grab?
Situation Best choice Reason
Drive-up park, operating from tailgate/table Door screen No pack size penalty, maximum RF area, ~$15
Hike-in activation, pack on back CHA FSR Two 6×4" bundles vs awkward 36" tube — no contest
Public park with pedestrian traffic CHA FSR Visible TAN strips, soft edges, survives being stepped on
Using Rybakov/MPAS system CHA FSR Integrated 3/8-24 adapter — direct mount, no adapter needed
Using 17' whip with separate base Either RF performance roughly equal; door screen wins slightly on area
Wet grass / muddy ground CHA FSR Oxford outer layer resists moisture absorption; screen corrodes over time
Long-term durability CHA FSR Door screen fatigues and tears at fold lines after repeated use
Budget-constrained Door screen ~$15 vs ~$90 — hard to argue with for occasional use
Bottom line for EN11xe POTA use: Your door screen is a legitimately good ground plane and the RF performance difference vs the CHA FSR is small — probably indistinguishable at QRP levels on any given contact. The real question is deployment context. If you're carrying everything on your back into a state park, the FSR wins decisively on packability. If you're pulling up to a picnic table at a roadside park, the door screen is perfectly fine and costs nothing extra. Carrying both for different activation types is a reasonable strategy.
EFHW deployment deep-dive — central US coverage strategy
Central Nebraska coverage context: For POTA, your typical hunter is 500–1500 miles away. On 40m that means you want moderate takeoff angles (30–50°) for regional contacts and some low-angle lobe for skip. On 20m and up, lower angles (15–25°) reach hunters across the continent. The deployment you choose shifts which of these you favor.
🔺 Inverted-V (apex up)
Best for40m regional, 30m
40m takeoff45–55° (NVIS-ish)
20m takeoff25–35°
15m takeoff18–25°
PatternFigure-8, broadside to wire
EN11 coverage on 40m~500–1200 mi all directions
Setup difficultyNeed 30'+ apex support
VerdictBest all-rounder
Apex at 30–35' gives excellent regional 40m coverage. Orient the wire N–S and you cover E and W hunters with the broadside lobes. On 20m the apex height provides low enough angle for good DX. Recommended default deployment from EN11.
Sloper (high end ~30', low end ~6')
Best for20m DX, 15m, 10m
40m takeoff30–40°
20m takeoff15–25°
15m takeoff12–18°
PatternDirectional toward low end
EN11 coverage on 40m700–1800 mi, directional
Direction gain2–4 dB toward low end vs inv-V
VerdictBest for DX hunters
Point the low end toward your target (NE for Europe from EN11, SE for Caribbean). On 20/15/10m the low-angle radiation is noticeably better than inv-V. Use this when a pile-up is forming on a DX band.
Near-Flat (both ends ~20–25')
Best for20m, 15m, 10m skip
40m takeoff30–45°
20m takeoff18–28°
15m takeoff12–20°
PatternFigure-8, broadside
Height requirementTwo supports at 20–25'
DeploymentTwo trees needed
VerdictGood when two trees available
Flattest radiation on 20–10m. Requires two good supports — less common in central NE parks. When you have them, it's the cleanest pattern for consistent performance across bands.
📍 Low Sloper (high end ~15', low end on ground)
Best for30m, 40m NVIS only
40m takeoff50–70° (NVIS)
20m takeoff40–55°
40m EN11 range~300–700 mi close-in
DeploymentVery easy — 1 support
Ground interactionHigh — lossy in wet grass
VerdictEmergency/no-tree fallback
Ground proximity hurts efficiency. Use only when you have nothing better. In EN11 with 5W, you will make contacts but the window is narrow.
EFHW counterpoise & coax shield — what actually matters
The fundamental issue: An EFHW transformer needs something to push against — RF current must go somewhere from the shield side. A counterpoise (or coax braid) provides this return path. Without it, RF flows back down your coax and into the KX2. This causes RFI, key clicks, hot chassis, and erratic SWR. The question isn't just efficiency — it's also station cleanliness.
Counterpoise length comparison — 40m / 20m primary analysis
Configuration 40m effect 20m effect RFI risk Practical verdict
17' wire, on ground Good (~½λ on 40m) Fair (resonant length issue) Low Solid general choice
17' wire, elevated 3–4' +1–2 dB vs on-ground +1–2 dB vs on-ground Very low Best wire option
33' wire, on ground Very good (full ½λ) Good (full λ) Low Best wire length overall
33' wire, elevated 3–4' +1–3 dB vs on-ground +1–3 dB vs on-ground Very low Optimal — use this if possible
No wire — 25' coax only Fair — coax braid acts as CP Fair — length-dependent Moderate–High Workable, not ideal
No wire — 15' coax only Fair on 20m (≈¼λ) Good (≈¼λ at 20m) Moderate Better on 20m than 40m
No wire — 10' coax only Poor on 40m Marginal on 20m High Avoid if possible
No wire, no coax (direct) Poor Poor Very High Don't do this
📐 Why coax length matters without a wire CP

When you have no dedicated counterpoise wire, the coax braid becomes your counterpoise. Its electrical length (not physical — velocity factor ~0.66 for RG-174/RG-58) determines how well it works on each band.

10' coax physical → ~6.6' electricalPoor CP on any POTA band
15' coax physical → ~9.9' electrical≈¼λ at 28 MHz only (10m)
25' coax physical → ~16.5' electrical≈¼λ at 17–18 MHz (17m)
33' coax physical → ~21.8' electrical≈¼λ at 14 MHz (20m)
66' coax physical → ~43.6' electrical≈¼λ at 7 MHz (40m)
Practical takeaway: With 25' of coax and no wire, you'll get decent performance on 17m but marginal on 40m. Add even a short wire (17') to fix this. With a wire CP in place, coax length matters much less.
⬆️ On-ground vs. elevated counterpoise

The gain from elevating a counterpoise is real but not dramatic for POTA work. At QRP levels the question is: does it make the difference between getting through or not?

On ground (dry grass/dirt)Baseline — some ground loss
On ground (wet grass)Worse — higher loss, variable SWR
Elevated 1–2' (on a pack)+0.5–1 dB — easy, do this
Elevated 3–4' (on a branch)+1–2 dB — noticeably better
Elevated 8–12' (on a pole)+2–3 dB — best practical option
Easiest field trick: Drape the counterpoise wire over your pack or a low branch. Even 18" off the ground measurably reduces ground loss. Takes 10 seconds.
🎯 EN11 field recommendation — EFHW setup priority
1st choice33' wire CP, elevated 3'+, inv-V
2nd choice17' wire CP, on pack, inv-V
3rd choice25' coax + 17' wire on ground
DX pushSloper + 33' wire elevated
Minimum viable25' coax, no wire (17m/20m only)
Avoid10' coax, no wire, wet ground
QRP reality check: At 5W CW, a 1–2 dB improvement from a better counterpoise is the difference between a weak signal and a comfortable copy. Don't skimp on the CP setup.
Quick deployment decision guide — EN11xe central US POTA
40m — regional pile-up
Best antennaInv-L or EFHW inv-V
Target range500–1500 mi
Takeoff needed35–55°
Time of dayAll day + evening
30m — steady contacts
Best antennaEFHW, Rybakov, Inv-L
Target range600–2000 mi
Takeoff needed25–40°
Time of dayAfternoon–evening best
20m — maximum contacts
Best antennaEFHW sloper, Rybakov
Target range800–3000 mi
Takeoff needed15–25°
Time of dayMid-morning–afternoon
17/15m — high-band run
Best antenna17' vert, Rybakov, EFHW
Target range1000–4000 mi
Takeoff needed10–20°
Time of dayMidday when SFI >120
10m — cycle 25 bonus
Best antennaAny — propagation wins
Target range1500–7000 mi
Takeoff needed7–15°
Time of dayMidday; watch for openings
Limited space / no trees
Best antenna17' vert on screen
Next choiceRybakov on fabric radials
Loop optionCHA TDL (20m+ only)
AvoidLow sloper, no CP
NotesPrairie parks: verticals win