A while back, Ron AC7AC designed, built, and kindly sent me a simple yet
elegant
rf current sensor that operates along with my DMM to give an accurate
quantification of
how my rig is delivering power to the radiator. More current equals more
radiation. One thing it allows me to do is to calculate power out into a
known load, and particularly relative to this discussion, it facilitates the
ability to make comparisons between different antenna configurations,
including the relationship between radiator and counterpoise.
Instead of a 1/4 wl wire, I use an MFJ Artificial Ground to tune a wire for
maximum current per given band. While measuring, one thing that
surprised me was to discover that with my 86' EFW, the use of a properly
tuned counterpoise didn't always increase the current to the radiator.
For example, on 40 meters the use of a counterpoise helped
to realize a substantial increase of current into the radiator, while on 80
meters I actually saw more current into the radiator with the counterpoise
unhooked on that band. The effects on 30-10 were really fairly minimal or
neutral in this regard.
73,
Mychael AA3WF
K2#1025
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