[Lowfer] Embattled E-Probe

[Ed Phillips]

I've been following the effect of trees on VLF reception.  My own
experience is about as follows:

	My antenna is a 50 foot Hygain "Hightower", tapering from the ground to
the top in such a way as to minimize the radiation resistance.  (Not as
much current toward the top as in a uniform wire or mast.)  It
originally was installed between two large old oak trees, whose trunks
were less than 20 feet from the tower and whose tops went way above it. 
The capacitance of this antenna is about 450 uufd, and the effective
series resistance of the ground plus the antenna was of the order of 40
ohms, a lousy combination but all I can manage with the base between the
house and nearby driveway and our dry soil.  Every year we'd have the
trees pruned and the resistance would go down a bit until the foliage
grew back as it will with California live oaks.  About four years ago
both trees died of "California oak root disease) and were removed.  The
resistance went down from about 40 ohms to less than 30, indicating a
significant loss due to the trees.  So , they were indeed "sucking up"
energy, although only by a dB or so.  I can certainly tell the
difference in antenna current for a given final power input.

	I don't use the antenna in resonance for receive so don't know what
effect the tree was having on reception.

Ed