[Lowfer] Alien e-probes

[WE0H]

So why does my Natural Radio receiver hear more pops and other signals when
I walk away from the trees and/or hold the receiver with antenna on its
enclosure up high over my head. I tried it on an 8' wood pole one night and
it was louder yet. The same goes for my LF-400 active vertical when I hold
it over my head or put it on a wood pole that I can hear my beacon's signal
louder when I am out several miles from the transmitter site.

Mike>WE0H


-----Original Message-----
From: lowfer-admin@mailman.qth.net [mailto:lowfer-admin@mailman.qth.net]
On Behalf Of Bill Ashlock
Sent: Tuesday, September 16, 2003 5:00 PM
To: lowfer@mailman.qth.net
Subject: Re: [Lowfer] Alien e-probes

Peter,

Let me ask this question: By adding a ground plane to the base of an E-probe
antenna mounted at, say, 55 ft,  you expect to increase the signal? You have
already increased the signal in proportional to the probe height divided
into 55 (=~ 18x) and you expect a bigger increase?

>what does one make of the AMRAD's LF probe using
>a smallish metal roof for GP and reported noise reduction and stated
>effective reception?

I believe the gain is not due to the improved ground plane but simply to the
metal roof providing a good ground to the return side of the probe - and of
course a higher signal measuring point which nets the expected signal
multiplier resulting from the increased height above ground. Suggest they
repeat this test with a good earth ground added to the coax shield under the
probe and with the probe height the same as the probe height on the roof.

Again the skinny hotel case:
>>I believe this effect is due to probing the changing E-field at two
>>locations 312
>>meters apart. The instantaneous voltage induced is proportional to this
>>distance as long as it is much less than a wavelength.

This is my explanation of why the antenna mounted on the top of the skinny
hotel would have a gain of 312X. I believe this hotel profile would actually
Decrease the signal somewhat because of its tendency to act as a secondary
ground plane.

When I began testing E-probes at increased elevation in the back yard (4
years ago) and saw impressive increases in signal strength. I posed the
question of "why" on this reflector. The universal answer was the shielding
effect of the trees. Next I raised the SVM along with the E-probe to the
same heights as before. I added a 3ft dangling ground plane to act as the
return for the probe and I was able to read the meter with binoculars. The
results indicated almost no increase in signal strength with height! Next, I
moved the equipment to a large open field and the results were the same.

Bill A

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