Just a minor comment on this much discussed topic.
A few years ago, when experimenting with toroidal antennas on top band, I
ran into the same problem. The local field from a toroid is entirely
electric and so the effect of the lossy earth was very severe especially in
the immediate vicinity of the antenna. After a bit of head scratching I
isolated the output circuit from all local earths and used a counterpoise
consisting of a single wire about 50cm above the ground terminating in a
metal plate about 1 metre square, insulated at the same height. I am still
using it.
Some of you may have heard my toroid on top band and will know how
well it works but if I connect the metal plate to ground the signal drops
by at least three or four S points. The major losses usually occur in the
immediate vicinity of the antenna, the propagation loss further away is
still a problem but is less severe than that in the primary launching
system.
Now I must sadly give notice that I will have to resign from this
net in the very near future. It was wonderful when the group was small but
the traffic has grown so much that I cannot keep pace with my normal email
and I regret that it must take priority.
73 to you all,
Roger, G2AJV.
|
