Topband: Monopole Elev Pattern w.r.t. Earth Conductivity

[Herb Schoenbohm]

I used or tried to use a 308 foot self supporting base insulated 
Blau-Knox in the late 70's and early 80's (Picture on QRZ.com) and 
although I could not do A-B tests I found it horrible and that was over 
a 2 degree  buried 260 foot radial ground system for 970Khz right next 
to the ocean.  I found better use for it by using it to run a rope up to 
the top and hung 1/2 wave slopers down to the sea, and that was much 
better for RX reports on 160 from Europe.  I really expected better 
results but was amazed at the difference over many years of testing.  I 
would drop the sloper(s) to the ground when trying to use the 308 foot 
free standing tower...which the books said would be an optimal low angle 
radiator.  The slopers and even a full sized corner fed delta loop were 
always much better.


Herb, KV4FZ




On 10/24/2012 5:44 PM, Tom W8JI wrote:
>> Did you --or anyone else you are aware of-- ever A-B test a ~120' tower
>> against a ~300' tower on 160?
>
> I A-B or A-B-C tested several antennas, including a low dipole, the 
> high dipole, an element from my four square, a ~318 foot insulated 
> tower vertical, and I think my tall omni vertical was about 190 feet 
> at that time.
>
> The tall vertical tower was definitely worse compared to shorter 
> verticals, and had almost no short skip signal around Georgia. I had 
> isolation chokes for lights and a base insulator, but that 300+ foot 
> tower was so poor I never used it as a vertical.
>
> By the way, to show how bad interaction is, I had to detune unused 
> towers even when they were 300 feet or so apart.
>
> If you recall W8LT and the balloon verticals, they didn't do so well 
> with that antenna at 5/8th wave. I used WSPD, WOHO, and WXEZ (King 
> Road 350 ft) towers also, but had no A-B tests.
>
> Anything tall or new received good reports, if I told the other person 
> it was tall or new. This is a common result, similar to the well-known 
> G5RV effects. Pick an unpopular antenna like a G5RV and say you are 
> using it in a test, and even if you do not actually switch antennas 
> the G5RV will get a weaker report over long averages of tests. You can 
> see a similar effect with guest operators and a no-change switch 
> position. They always like the better antenna, even when it is the 
> same antenna.  :-)
>
> To avoid the G5RV effect when making A-B tests, I never said which 
> antenna was actually A or B. I also would randomly change A or B 
> around in different tests. Just watching reports without changing 
> antennas at all is interesting.
>
> 73 Tom
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