[Lowfer] Alien e-probes

[Bill Ashlock]

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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