Hopefully this will be a blog about practical experience with tuned loops, and in particular, the “Edginton” Quarter-Wave tuned Loop designed by Ben Edginton, G0CWT. To date, I have built Edginton loops for the 20 meter, 40 meter, 80 meter and 160 meter bands in various form factors from 4 ft sq for the 20m band through to a 16′ (vertical) x 40′ (horizontal) version for the 160m band. The 160m version used two sets of 6 ea. 4′ military tent poles and guy ropes and occupied a good portion of my small city-lot’s backyard.
In the genre of “tuned loops” the Edginton (G0CWT) Loop has the following positive attributes in contrast to smaller (<1/10 wavelength) tuned loops:
1) a reduced requirement for the tuning cap’s voltage rating (as contrasted with the smaller tuned loops). Also recall that even the basic half-wave dipole antenna exhibits high RF voltages off the ends!
2) a relaxed requirement for the size (and conductivity) of the conductor forming the loop (i.e. wire is suitable for use instead of heaver, costlier copper tubing or pipe.)
It should be noted that short lengths of coax line (and/or preferably low-loss Heliax cable) can be substituted for the ‘bulk’ (i.e. most of) of the tuned loop’s tuning-capacitor’s capacitance. For instance, on a 160 meter QW Edginton loop approximately 36″ of Heliax cable is needed for the ‘bulk’ of the capacitance (aside from the trimmer capacitance) and for forty meters only 10 inches of Heliax is needed.
An example of a 40 meter QW tuned (Edginton) loop formed on cane poles can be seen below at this link: