Why the Contest Inverted-L Stayed Up After the Vertical Came Down
Why the Contest Inverted-L Stayed Up After the Vertical Came Down
Three contest operators told me versions of the same story: they tried an EFHW inverted-L for a contest weekend, preferred the result, and did not reinstall the vertical. The story is useful—but the reason must be measured, not guessed.
Contest stations do not choose antennas in a vacuum. Deployment time, available supports, soil, radial space, feedline routing, matching loss, station interaction and the paths that are open all affect the result. An antenna that is easier to reproduce can be the better contest system even when another geometry could win under ideal conditions.
What the story proves: those operators preferred the complete inverted-L installations they tried. It does not prove that every EFHW beats every quarter-wave vertical, or that an end-fed antenna works without a return current.
The Vertical May Have Lost in Its Ground System
A ground-mounted quarter-wave monopole has high current at its feedpoint. That current must close through the radial and soil system. Loss resistance in that return path dissipates accepted transmitter power, and the effect depends on the complete current distribution—not simply on whether some wire lies on the ground.
Rudy Severns, N6LF, measured real HF vertical systems while changing radial number, length and elevation. His work shows why radial performance cannot be reduced to “more wire is always better” or one universal radial count. Sparse systems, conductor length, proximity to soil, symmetry and nearby objects can change impedance, current division and measured field.
A properly engineered vertical with an appropriate on-ground or elevated return system remains a serious antenna. The contest anecdote is most plausible when the earlier vertical had a lossy, asymmetric or inconvenient return system and the replacement inverted-L created a more repeatable complete current path.
No Radial Field Does Not Mean No Return Path
An end-fed half-wave is fed near a high-impedance region of its installed current distribution. The feedpoint current can be lower than at the base of a quarter-wave monopole, but it is not zero. The matching network still needs two terminals, and displacement and conductor current still close through the installed system.
The return may include an intentional counterpoise or local reference, transformer and enclosure capacitance, the feedline exterior, support hardware and nearby conductors. If those paths are not controlled, the antenna may still make contacts while changing every time the coax route, shack bonding or weather changes.
I therefore use “without a radial field,” not “without radials” or “without ground.” The distinction matters: the antenna can avoid a large monopole-style radial screen while still requiring an intentional and measurable RF return.
The Transformer and the Choke Solve Different Problems
The impedance transformer must suit the complex end impedance at its own reference plane over the intended bands and power. A familiar turns ratio does not guarantee 50 Ω, low loss or acceptable heating. Primary inductance, leakage, winding capacitance, ferrite properties, core volume, voltage stress, duty cycle and cooling all contribute.
The common-mode choke sets a boundary for current on the feedline exterior. Its placement follows the measured exterior-current distribution and the return structure you intend to keep. A copied rule such as a fixed fraction of a wavelength down the coax can accidentally create another resonant section or move the current maximum without controlling it.
Measure the transformer load and temperature separately from exterior-feedline current. A low SWR at the transmitter does not prove either low transformer loss or a quiet coax exterior.
A Ground Stake Is Not the RF Counterpoise
A metal stake can add capacitance and conduction to soil, but its RF impedance is frequency-, soil- and geometry-dependent. It does not replace a declared return conductor, and it must not be confused with the station's protective bonding or lightning system.
Do not create an isolated earth electrode as an antenna experiment. Any electrode, mast bond, coax entry or surge protection must follow the building's coordinated earthing and lightning design. Keep the RF comparison inside that safety boundary.
The L Shape Creates a Pattern, Not Two Guaranteed Services
The vertical and horizontal sections both carry current. Their relative lengths, heights, bends, ground, support conductors and return path set the azimuth and elevation pattern. The result can contain useful low- and higher-elevation radiation, but “vertical section for DX plus horizontal section for local work” is not a guaranteed split.
ITU-R BS.705-2 distinguishes calculated antenna patterns from the effects of ground, topography and surrounding structures. NEC can model the declared wire, return conductor and feedline segment, but the model must match the installed geometry and ground assumptions. The contest path then decides which parts of the pattern matter.
Why Contest Operators May Keep It
A contest antenna earns its place through more than peak field strength. An inverted-L can be attractive when it:
- uses supports already available at the site;
- avoids deploying a large ground-level radial field;
- creates a repeatable transformer, return and choke arrangement;
- covers the required bands without repeated mechanical changes;
- survives weather and operator changes; and
- reduces setup time without compromising station safety.
Those are operational advantages. They do not assign an efficiency, gain or take-off angle. In a contest, the lower-effort system may also stay on the air longer and be easier to repair, which can matter more than a small modelled difference.
How to Find Out Why One System Won
| Question | Measurement | What it separates |
|---|---|---|
| Did the vertical lose power in its return system? | Document radial geometry, individual currents, feedpoint impedance and accepted power | Radiator behaviour from radial/soil loss and asymmetry |
| Did the EFHW use the coax as an uncontrolled return? | Map exterior-shield current at repeatable positions before and after the intended choke | Radiator current from feedline participation |
| Was the transformer responsible? | Measure complex load, insertion loss or calorimetric rise, temperature and duty-cycle margin | Matching convenience from magnetic and winding loss |
| Did the patterns suit different paths? | Model the installed geometries and compare calibrated field or simultaneous remote reports by bearing | Pattern difference from total efficiency |
| Did propagation drift during the test? | Use rapid A/B/B/A switching or simultaneous receivers and restore the baseline | Antenna change from time-varying ionospheric conditions |
Keep transmitter power referenced at the same point, account for feedline loss and verify switch isolation. A cluster of contacts or one weekend score is valuable operating evidence, but it does not isolate the cause.
High-voltage boundary: an EFHW has high RF voltage near the end-feed hardware and wire end. Keep it inaccessible to people and animals, provide clearances, strain relief and weather sealing, and verify transformer and choke temperature at the intended power and duty cycle.
Bottom line: I believe the operators who said the inverted-L stayed up. I do not turn their choice into a universal antenna law. The engineering explanation is the complete system: radiator current, return loss, transformer loss, coax-exterior current, installed pattern and contest practicality.
Measurement foundations
- Rudy Severns, N6LF — Experimental Determination of Ground System Performance for HF Verticals, Part 1
- Rudy Severns, N6LF — Ground Surface and Elevated Radial Comparisons
- ITU-R BS.705-2 — HF Transmitting and Receiving Antenna Characteristics and Diagrams
- Numerical Electromagnetics Code (NEC-2) User's Guide
Mini-FAQ
- Is the EFHW inverted-L really a no-radials antenna? It can work without a large monopole-style radial field, but it still needs a return current through an intentional conductor, local reference, controlled feedline section or a measured combination.
- Where should the common-mode choke go? Place it from an exterior-current map and the return boundary you intend to keep. A fixed wavelength fraction is not a universal answer.
- Why can it beat a quarter-wave vertical? It can beat a particular vertical when the vertical's radial/soil return is lossier or less repeatable, or when the inverted-L pattern and operating convenience better suit the paths. That is not universal.
- Does the horizontal leg point the antenna? It can influence azimuth and elevation pattern, depending on current, height, ground and surroundings. Model and measure the installed geometry.
- Does a low SWR prove the transformer is efficient? No. SWR describes the impedance presented at a reference plane; transformer loss, heating, voltage stress and common-mode current require separate tests.
- What is the fairest comparison? Compare complete installed systems at the same accepted-power reference using rapid A/B/B/A or simultaneous field measurements, with feedline loss and propagation drift controlled.