ZS6BKW: A simple wire antenna that surprised me big time

My permanent antenna lineup includes a DX Commander, a MyAntenna 75–10-meter wire installed in a near-vertical configuration, and a Palomar off-center-fed antenna. A Buddihex also makes an occasional guest appearance for contests, but it is not a permanent installation.

For the most part, the ZS6BKW has outperformed my other permanently installed antennas in everyday operation. I would leave the Buddihex out of that comparison: it comes out for different occasions, and I have not made a consistent comparison with it.

What has surprised me most is the ZS6BKW’s long-distance performance, along with reports of clear, strong audio from stations thousands of miles away. For a simple wire antenna, it has certainly earned its keep.

My installation is hardly a textbook drawing. The feed point sits approximately fifteen feet above the ground, and the wire rises along a gentle slope to forty-some-odd feet at the T. Its ends extend toward the northwest and southwest. The ground slopes beneath it, so the clearance varies along the span. Think of it as a T with a little personality.

The ZS6BKW is essentially a multiband doublet with a transmission-line matching section designed to feed a run of 50-ohm coax. The balanced window-line section transforms the antenna impedance toward a useful coax match on several bands; a separate one-to-one current choke provides the balanced-to-unbalanced interface. For this installation, we compare 100- and 150-foot coax runs. Those lengths suit the route to the shack rather than being a universal tuning requirement.

A doublet fed entirely with low-loss balanced line to a suitable tuner can avoid the extra coax loss encountered under high mismatch. The ZS6BKW offers a convenient compromise: useful matching on several bands and a coax connection to the station. The build and purchase options below explain that tradeoff rather than promising the same performance on every band.

Based on my experience, I would recommend the ZS6BKW as a strong candidate for a first antenna build—or a first wire-antenna purchase if you would rather get straight to hanging it. This post covers both routes: a homebuilt version first, Palomar’s prebuilt version second, and a comparison with NI4L’s version last. Each has labeled drawings and linked parts, with approximate costs dated October 18, 2026.

If space is limited, a compact Junior alternative is also noted. Its supplier dimensions and the construction details still needing confirmation are identified separately.

These are my results at my location, rather than a controlled comparison, but they have certainly earned this antenna a place in my yard.

ZS6BKW antenna build and purchase guide

Homebuilt first · Palomar second · NI4L comparison last
Revised October 18, 2026 · Prices in US dollars

1 Homebuilt full size antenna

Build a center-fed wire radiator with a balanced matching section and a 1:1 current choke. These dimensions are provisional starting targets for adjustment in the final installation, not an exact reproduction of either commercial antenna. [1–4]

Cut and adjust

Start with two equal radiator legs slightly longer than 13.95 m. An extra foot per end is a working tuning allowance, separate from the final conductor length. Fold back temporarily, sweep with an analyzer at low power, and adjust both sides equally. The line target is 13.6 m electrical length x 0.91 VF = 12.376 m physical length; keep connection leads short.

Power assumption: 600 W for SSB, CW and digital; Palomar capability at high mismatch is accepted for planning, not independently verified. In the US, 30 metres is limited to 200 W PEP; 600 W loss examples on that band are calculations only. [12]

Homebuilt installation and parts

Buy these homebuilt components

Primary antenna parts budget: about $280, excluding coax, mounting extras, tuner, tax and shipping. Choose either radiator wire, not both. Palomar lists its wire as stranded PVC insulated; the reviewed listing does not identify the conductor alloy. Retune after a wire substitution. RF Connection line is a separate alternative on the NI4L page.

2 Palomar prebuilt five kilowatt version

Choose PAL-ZS68006-5000, the 5 kW PEP version, for an assembly with its 1:1 CUBE interface balun already included. Its power label differs from a continuous high-SWR rating; the agreed planning assumption remains in effect. [5, 6]

Why both 92 feet and 88 feet appear

The manual ships each leg at 46 ft and illustrates a sample using 44 ft per leg. Fold back the outer wire ends to tune before trimming. It uses a 40 ft matching section; its sample SWR curve was obtained through 20 ft of RG-213 at about 30 ft average height. That curve is not a test of our 100 or 150 ft coax run. [5]

Parts and purchase

No second interface balun is needed merely to duplicate the supplied CUBE. Add the shared coax and mounting materials in the shopping list.

3 NI4L prebuilt comparison

NI4L follows the same full-size ZS6BKW principle. Its radiator material and fully specified FLEXI line distinguish it from our build. The current listing does not explicitly establish an included choke, so the diagram shows the external choke in our plan. [7]

What changes from our build

NI4L lists POLYS-13 copper-clad steel with polyethylene insulation, rather than the homebuilt DXE 14 AWG stranded copper PVC wire. Its 40 ft matching section is nominally 420 ohms with VF 0.917; ours uses approximately 400 ohms and VF 0.91. Line impedance and electrical length both matter, so the lengths are not direct substitutions.

Parts and purchase

RFC 552 matches NI4L’s published line specifications; this does not establish a shared manufacturer. Preserve the prebuilt matching section. Buy loose line only for a separate build or replacement. [8]

Compare the three options and coax lengths

Power at the choke and antenna system: 600 W

Assume 600 W NET entering the coax after tuner losses. These figures exclude choke, window-line and radiator losses; they are not radiated power. A reading of 600 W forward on a directional meter is a different quantity.

Estimated with UltraFlex 10 Competition attenuation at 20 C near 3.5, 10 and 21 MHz: 0.9, 1.2 and 1.7 dB per 100 m. For L dB cable loss, let A = 10^(−L/10) and g = (SWR−1)/(SWR+1). Efficiency relative to net input is A(1−g²)/(1−g²A²). Rounded to 5 W; connectors omitted. Verify the purchased cable version. [9]

The additional 50 ft costs about 45 to 60 W at 9:1, roughly 0.5 to 0.7 dB. Use 150 ft if it enables a better installation; otherwise 100 ft reduces loss. A tuner can change the match at the transmitter but does not remove the mismatch beyond it.

30 m note: In the US, 30 metres is limited to 200 W PEP; the 600 W entries above are loss calculations only, not operating recommendations. [12]

Comparison: 1,000 W net entering the coax

Same cable lengths, attenuation and load SWR assumptions as the 600 W table. Values are calculated before choke, window-line and radiator losses; they do not establish the choke’s power capability. The 30 m row is a mathematical comparison only: US amateur operation on that band is limited to 200 W PEP.

At 1,000 W, the extra 50 ft loses approximately 75–100 W more at 9:1 SWR, depending on band. Cable efficiency is unchanged from the 600 W case; the watts lost increase in proportion to input power. Calculated independently from the attenuation model and rounded to 5 W. [9, 12]

30 m note: These values are hypothetical calculations for comparison only. The US 30-meter limit is 200 W PEP; do not read the table as an authorization or recommendation to transmit 600 or 1,000 W there. [12]

Shared shopping list and budget

Approximate prices reviewed October 18, 2026. Posted means visible in retrieved supplier material; allowance means a rounded planning estimate, not a current vendor quotation. Prices can change. Tax, shipping, tuner, amplifier, grounding system and site engineering are excluded.

Buy one coax length, not both. Listed coax assemblies already have end connectors; do not add a second connector charge. GigaParts also displays conditional VIP or rebate pricing; this budget uses regular prices. Rope and support quantities must be checked against the site.

Approximate package budgets

Totals use about $90 for rope, weatherproofing, terminals, coupler and mounting allowance. Not every prebuilt installation needs every item. NI4L total is provisional until the exact coax choke and price are selected. For a new balanced termination, the separately priced CUBE is an available alternative, but replacing the NI4L connector is additional work.

Technical references and compact Junior note

The full size design principle is supported by RSGB and Austin. The exact homebuilt dimensions here are a provisional commonly documented variant. Manufacturer specifications establish purchased materials, not independent validation of our entire installation.

1. RSGB Successful Wire Antennas, ZS6BKW discussion, printed page 103
2. Brian Austin, The ZS6BKW Antenna from the horses mouth
3. Practical Antennas, multiband dipoles, dimension cross check
4. DX Engineering DXE-LL450 specifications
5. Palomar ZS6BKW product manual, 2023
6. Palomar prebuilt model and 14 AWG retailer description
7. NI4L construction and matching line specifications
8. RF Connection RFC 552 balanced line catalog
9. Messi and Paoloni UltraFlex 10 data sheet
10. Palomar CUBE rating and hardware options
11. Palomar 14 AWG wire specification and price
12. ARRL Part 97 text, section 97.313(c)

Bibliographic reference: B. A. Austin, “An HF multiband wire antenna for single-hop point-to-point applications,” Journal of IERE 57(4), 167–173 (1987). Full text and its peer-review process were not verified. The source is not presented as a separately reviewed construction validation.

Compact Junior remains a separate alternative

The selected supplier Junior describes a 14.2 m horizontal span, 7.5 m drop and 11.91 m of 450 ohm matching line. Exact fold/return geometry, wire gauge and one-foot spacing are unresolved. Independent handbook or journal reference for this exact layout: not provided. Do not build it by halving the full size matching line.

Junior supplier specifications

A final word on chokes and responsibility

Other current chokes and baluns are available from a variety of manufacturers and suppliers. Review the specifications for the exact unit you are considering, including its frequency range, operating mode, duty cycle, and any limits under mismatch. A power rating by itself does not establish that a choke will handle your installation.

When in doubt, I prefer substantial power-handling headroom and the highest suitable rating I can reasonably obtain. Even that is not a guarantee: extreme mismatch and common-mode current can overheat or damage a choke, including one rated well above your transmitter power. If the mismatch cannot be properly characterized, do not assume that a larger wattage label makes it safe. Use caution, begin at low power, and follow the manufacturer’s operating limits.

This article describes my own work and experience. If you choose to copy or adapt my installation, you do so at your own risk and accept responsibility for your equipment, installation, operation, and resulting consequences. I make no guarantee of performance or suitability for your station and accept no responsibility for damage, injury, or other consequences arising from your use of this information.