Discussion in 'Amateur Radio News' started by KM9G, Oct 6, 2021.
NVIS, Sloper, Inverted Vee, Vertical... which one does better?
You cannot tell anything about the radiation pattern of the antenna without extant knowledge of the ionospheric propagation in the various layers. It changes with time, time of day, launch angle, and frequency.
For antenna comparisons -
I found that FT8, for some reason, had really inconsistent signal to noise ratios on the same signal, from the same antenna, fed to two identical SDRs, running on the same model computers. WSPR, under the same circumstances, was much better, with reported SNRs identical or within 1 dB. But to get rid of the ionospheric variables that change second to second, the comparisons need to be made simultaneously, whether for receiving or transmitting, between two antennas at least 1 wavelength apart.
WSPR was intended for this sort of thing.
I put a Patriot CB antenna 3 ft off the ground on ft8 on 12 meter and get a almost perfect match.(without tuning) Then started hitting stations over 8000 miles away with 50 watts. Then I swapped out for a Solorcon A99 on the same mount. moved the tuning rings to the bottom, and got a near perfect match on 17 meters and bottom of 10 meters, and once again, but on on 17 meters I was hitting stations over 8000 miles away on 17 meters. On 10 it was all US stations. And the band conditions were poor to none. And the antennas were up into tree branches. Put up a resonant vertical antenna and work the world from a ground mount. PS there were no ground radials just 50 ft of cheap coax, and antennas were checked at the base for swr. The mount post was a T post just far enough in the ground to be stable. My little rinkydink test showed amazing results with cheap CB antennas. Use you imagination for antennas, You would be amazed with what works. PS use a rf choke to help keep it clean.
The comparison is on HF really difficult. I tried this by myself with a homebrew 80M halfwave folded longwire and a QRP transceiver. And when I compared where I could reach out, it was always depending on the daytime. Mostly here to say that the Greyline with its multiskips were most powerful. But in cause of the halfwave design and the special angle of the radiation, it was under normal conditions only possibel to reach stations near to the borders of Germany. Equal which direction. The rest within the country wasnt reachable. So the daytime, the angle of the radiation and the frequency itself should have the most attention on it for a comparison. And at next there should be several days of a comparision to find the middle. Further when there a stations from far away, these are only contacts for the moment and not for to compare the antenna designs.
The answer to your question also depends on that absolutely critical variable that practically nobody mentions: the antenna's environment.
For example, for DX, and if you work at the seaside, a vertical antenna will dramatically outperform any horizontal/mixed polarisation antenna, even when that antenna is a 3-ele Yagi (or more). Yes, I've done the research, as have many others, and any informed DXpedition to an island/coastal location will use verticals.
For NVIS, well, yes, that may be of interest in the US and to older operators in Europe on the lower bands. Verticals are generally not ideal for that, of course.
Reading «FT8» in captions I quit.
My mistake if, by chance, you mentioned later on using http://shop.spacew.com/index.php/product/proplab-pro-hf-radio-propagation-laboratory/
Anything else keeps us into an under-amateurs category, so, absolutely no need of another YT movie, unless purpose were to keep the hobby vulgus.
Interesting test, It would have been much more accurate using a Flex receiver, where multiple slices could be opened using different antennas simultaneously.
Another thing that can affect would be the lay of the land in your area in relation to the elevation at your location, especially if your QTH is hilly and not flat.
Of course propagation follows the Sun and the concentration of radio operators to the West is much less. Just my thoughts.
Something I tried several years ago that was interesting, involved using Gridtracker, a tee connector to same antenna and different
receivers to see which receiver work the best out of the box on FT8 - I based it on the total number of decodes in a given time. Radios I used were
Kenwood TS-2000, TS-850S, K3, KX3 and IC-7300.
73 de Bill WW5M
A NVIS antenna will have a wide main lobe and coverage roughly 50 degrees all sides from zenith.
An inverted V has a flattened hemispherical pattern,
The lower angle coverage for the inverted V will be sensitive to ground.
The point is that with all the free versions of NEC available, you already know the antenna power patterns, and any alleged deviations in expected coverage will be the result of propagation in the ionosphere.
Most hams on HF use FT8 for DX, not 300-600 KM local. That means, in general, low angle coverage. NVIS is designed exactly the opposite of that.