I used the search function and read many interesting articles for an hour or so. I didn't find the right thread to "my question".... maybe it is there, but I didn't find it, sorry.
One of the important questions when building a vertical is: ground or elevated radials...... this is discussed in many forums, I don't want to start this here again......but:
Q: In a 4 square with elevated radials - how many radials of what lenght and in which shape should one install to have the best performance?
some of us building a 4 square do not have the chance using ground radials. So we MUST use elevated radials.
I am one of those who "believes" that "4 elevated radials can come VERY close to a 60-120 ground radial system" or at least I must hope because I have no other chance.
If I could lay down 30 to 60 ground radials per vertical I would do it......
Because I can't I have to find out, which is the "best way to go" to install elevated radial(s) in a 4 square (phased array).
ON4UN is using 1 elevated radial per vertical but he also has the 160m radials under his 80m 4 square which definately helps.
Using only one radial results in "some" high angle radiation and he like's to have this. I think it is for better F/B ratio of high angle signals and so for attenuating unwanted European signals. But maybe it is also because with one radial per vertical, there is no problem with interaction between the radials.
So if using two radials in line, the radiation from it would be cancelled and there is less high angle radiation. As far as the radials from one of the three other verticals are not interacting and messing up the system. I would prefer avoiding the high angle radiation. I think without the gorundscreen of that 160m vertical I am loosing enough efficiency, don't want to loose even more.....
Is it better to use non-resonant radials ? I know it is better to use common coils for each feedpoint ( not a single coil per each radial)(so you need 4 coils for the 4 square)
I have seen a system where the radials ( 2 per vertical ) where folded inside the four square ( like Moxon-Style).
If you have the following possibilities to set up your ELEVATED radials, which would you choose? (remember: Groundradials are NOT possible) Any URL to a homepage of someone using it or a call sign I can google for ?
a.) One quarterwave radial per Vertical (aka ON4UN) (but without any 160m ground radials.....)
b.) two 14m long radials per vertical with a high-Q coil ( 1 coil per feed point) (radials going from the feedpoint 14meter inwards to the center of the 4 square and 14m outwards)
c.) four 1/8 wavelenght radials per vertical with a high-Q-coil ( 1 coil per feedpoint) ( which shape ? x+ or ++ or XX
+X ++ XX
d.) two quarterwave radials per vertical aka Moxon ( folded to fit INSIDE the 20m x 20m square)
e.) one quarterwave radial per vertical - folded back to cancel the radiation from it, so NO horizontal(high angle) radiation - ( think also the fewest interaction between radials of other verticals ?)
like this: O= feedpoint O-----------------|
not to scale ( see page 57 at http://www.oevsv.at/export/oevsv/download/QSPArchiv/2009/QSP200910.pdf )
I have 4 fullsize verticals, the feedpoint are at about 9ft above the ground. The radials will be 9ft or I can even rise them to 12ft. I think to remember that the higher the elevated radials, the better.
I think 15ft is a good height for 80m elevated radials
I will set the resonance frequency of each vertical to 3520khz minus 5% = 3344khz. When all 4 verticals are set up, the resonance will shift up to 3520.
When using the DX-window 3790-3800 I want to use a relay at each each feedpoint to insert a capacitor to shorten the vertical radiators.
Or when using coils for the nonresonant radials changing the tab point of the coil.
I had a lot of RG59 coax which is 75 Ohm and 0,66 velocity factor, so I used 3*quarterwave lenght of it (measured not calculated!) for each of the 4 feedlines. The advantage is, I have the DF6QV-Hybrid (like Comtek-Hybrid)http://www.ov-n15.de/joomla/images/zoom/VFHZZJ/df6qv_final_eng.pdf
and the Dummy load with the Dump-Power-Meter in the shack, not outside in the 4 square center, where it is raining :-) )
It is not the question if elevated radials will work or not or how much better groundradials could be.
Also with elevated radials it is better to have more than just one (I think)
So the question is: In a 4 square with elevated radials - how many radials of what lenght and in which shape should one install to have the best performance?
please have a look at www.dl2obo.com
and click on ANTENNA and/or MY 4 SQUARE INFO
Thanks for reading this, thanks for any help in advance.
please send me / post here some links to homepages/forums where this is published or post some calls I can google for.
I havn't found too many dispcriptions on 4 squares with ELEVATED radial(s).
73 Tom DL2OBO / T88DL www.dl2obo.com
Hotel Hellers Krug***
Altendorfer Str. 19