[TowerTalk] abreviated radial systems

[jimlux]

Rudy Severns wrote:
> I have recently completed a series of tests comparing the signal strength 
> between a 40m vertical with 32, 1/4-wave, radials in a complete circle to 
> the same vertical with a sector missing from the radial system.  This 
> represents the case of placing a vertical near an obstruction such as a 
> building.  Even over my rather good soil the results are discouraging. 
> There is signal reduction in all directions but the greatest reduction is 
> towards the missing sector.  I observed from 0.5 to over 3 dB of signal loss 
> in various directions.  Over poor soils these numbers would be even worse. 
> This does not take into account the loss due to a building in immediate 
> proximity to the vertical which is not likely to have a positive impact. 
> NEC modeling gives similar results to my experiments, overall signal 
> strength is down and the pattern is distorted.
> 
> These results will be published in the Nov/Dec 2009 issue of QEX magazine. 
> In the meantime I suggest that placing a vertical against a building is 
> probably a bad idea.  If you have any other option, take it.
> 
>

Interesting.. of course, you're talking about a compromise installation 
of sorts, so perhaps the 3dB less signal is more than compensated by 
more than 3dB less hassle from the HOA/spouse/etc.


  It's good to have actual test data.  ANother thing I've always 
wondered about, but hadn't come up with a good way of testing, is the 
added loss from the house next to the antenna. There's going to be some 
absorption, but just how much?  I guess you could set up a probe some 
distance away, and then move the antenna around.


3dB isn't great, but OTOH, it's a reasonable bump for an amplifier (e.g. 
if you ran 100W before, a fairly small amplifier would more than 
compensate.. at the risk of EMI/RFI or RF exposure limits)..

Of course, if you're "I hate to be weak Mike W4EF" and already running 
the limit....