20 meter 100 watt RML-20 (Resonant Magnetic Loop) antenna

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Alpha Antenna makes the most efficient Magnetic Loop Antennas available from any manufacturer. The 20 meter 100 watt PEP SSB (CW is 50 watts) Resonant Magnetic Loop (RML) is tunable for a SWR of 1.21:1 anywhere from 14.000 MHz through 14.350 MHz using the connectionless Variable Inline Capacitor (VIC). This Resonant Magnetic Loop (RML) maximizes ERP, and is not compromised with:

a) connections on the outer loop that would otherwise introduce losses,
b) miniaturizing its' naturally magnetic resonant size that would otherwise decrease efficiency,
c) forced resonance using a lossy capacitor that could otherwise cause severe negative efficiency ratings.

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Example of customer mount made from PVC

Manual: User Guides

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This is a 5 1/2 foot wide antenna that is a 100 watt 20 meter Resonant Magnetic Loop (RML20), which offers full coverage of the SSB or CW portion of the 20 meter band and is 95% to 83% efficient as a resonant dipole that is mounted at resonant height; according to the 66pacific and KI6GD calculators, which calculators which assume zero connection loss, zero ground loss and an infinitely high capacitor Q. RMLs for other bands will be released at undetermined dates.

Why buy a Resonant Loop?

What's so special about a Resonant Magnetic Loop anyway? EFFICIENCY+100W! The typical & common magnetic loop that is about 3 feet in diameter has an efficiency of around 27%. This RML has an efficiency of approximately 95% to 83% on both receive & transmit. Plus it handles 100 watts!


Recommended mounting height to maximize effective efficiency is one loop diameter or higher. Can be mounted lower, with variable impacts to efficiency.

You supply the support-mount and we supply the antenna. This antenna can be mounted in many different locations. The mounting of the RML is only limited by your creativity. Some of the mounting locations that are possible include;
a) Attic installations; where the antenna is located greater than 18 inches from electrical wiring and other metallic or flammable materials.
b) Vehicle installations; where the antenna is mounted inside a fiberglass camper shell or on a roof rack with user supplied standoff insulators,
c) Tripod installations; there are after-market and creative ways to build mounts using PVC and mounted on a tripod as the support.
d) Tower installations; we haven’t figured this one out yet, but we know the creative genius of amateur radio operators will.

Radiation Pattern

The loop may be mounted horizontally for an omni-directional radiation pattern. Alternatively, the loop can be mounted vertically, which will provide a null through the center of the loop and directivity off all sides.


Adjustable 125 KHz wide SWR null of 1.21:1 through 2.5:1 can be moved from 14.000 MHz through 14.350 MHz using the VIC.


-T-Connector for with SO-239 where you connect your coaxes PL-259
-Adjustable/tunable variable inline capacitor (VIC)
-LMR400 Outer Loop
-LMR400 Inner Loop

Technical Manual - 20 Meter Resonant Magnetic Loop

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