One square-flange BNC female chassis jack, for connecting the coupling.

Single-strand installation wire, or thin copper or brass tubing.

coupling loop, made of 60 cm (≈2 ft) heavy.toroidal ferrite core (inner diameter large enough.I used a box measuring 11圆x3 cm (≈4¼x2¼x1¼ A small ABS-plastic project box (not metal!), for housing the capacitor and the SO-29 jacks.Johnson capacitor type 167-12-1 isĮqually suitable: 12-202 pF (I measured 10-200 pF). Rotation of this capacitor's shaft is not limited, so it is easy to The minimumĬapacitance should be as small as possible, as it limits the highest achievable Two SO-239 chassis jacks if using coax, you can short-circuit the braid and the center conductor.Quality connectors, with teflon centers - not cheap plastic that completely meltĪway when a soldering iron is in the same room. To keep loss-resistance low over time, use decent.The plugsĪre installed on the ends of the copper tubing (or coax). Two PL-259 plugs for 10 mm coax ( note: do not use PL-259 that is meant for another coax diameter - one size does not fit all!).It is less expensive than copper tubing, but also less rigid, and not available at my local Do It Yourself store or any other store near my QTH! Good coax such as LRM-400 could also be used.Such tubing is sold in rolls, and used in refrigeration The loop: soft copper tubing with an outsideĭiameter of 10 mm (3/8 inch).2F for caveats about calculators! 10 mm (3/8') copper tubing, 5 milliohm loss included) 1: Calculator results for a loop with a diameter of 1 m (3.2 ft) (calculator: ref 2B note: read ref. Loop antenna calculators suggest that a loop of that size can be tune from 40 to 10 mtrs with a variable capacitor of 10-180 pF. This STL antenna must be be easily (trans)portable. No part of this publication may be used without permission from the author. coupling methods, please see my 80-20 STL page. You can make one yourself for a fraction of that price.įor a general introduction to Small Transmitting Loop antennas ( STL, a.k.a. Such loops are available commercially for several hundred euros/dollars.

So I needed a portable loop (40-20 or 40-10). Mid-2012 I acquired a portable QRP rig: a Yeasu FT-817ND (HF + 2m + 70cm,ĥ watt). It is currently disabled in your browser! Please (re-)enable it for full functionality. My website uses JavaScript for menus etc.

Loop antenna calculator download