Hi All,
By looking closely at the electrical configuration of an aerial system with
a tuned counterpoise the effects can be explained by reasoning as well as
calculations/simulations. I have posted a schemetic diagram on my homepaged
to avoid problems when sending it with the mail via the reflector. It can be
found at http://www.xs4all.nl/~misan/aecp.jpg (abt. 40kB filesize). Or
requested by email :mailto:[email protected].
The scematic shows an increase in antenna current (i) will be caused by the
added capacitance (Cxtra) between earial wire and counterpoise wire. The
second benifit is the apparent reduction of earth losses (Re) when the tuned
counterpoise impedance (Rres2) is put in parallel.
I think on LF the added capacitance to the earial system is the main factor
for an improved antenna current. By improving the Q (decreasing the
impedance Rres2) of the counterpoise circuit (increasing insulation/height
and/or high Q tuning coils) the effect of the counterpoise impedance will
increase. The proof of the pudding is in the eating. On HF reception
strength increases when adding a tuned counterpoise. Does the same thing
apply on LF???? If this is the case it is safe to assume there is an
increase in transmitted power as well.
Measuring the current to the ground system is a useful tuning aid for the
counterpoise. When the current to the earth system (Re) reaches a 'null' the
system is in tune (Kirchhoff's law).
Greetings and best 73's
Michael Sanders, PA3BSH
[part of original message]
One other thing discovered in all this....... at first I had the ANT and
Counterpoise coming in throught the wooden >window frame but only about 7
inches apart. I had terrible problems with arcing over to the window frame.
Tried >everything, double insulation etc etc , but no good. However once I
seperated them by about 20 inches , it all stopped >and no further problems
with arcing over to the window frame.
WELL , what do you think.
Best regards
Finbar EI0CF Malin Head
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