So since Jully 2013 now "version 4" , definitiv antenna design : with some 2.5mm² wire, coil 71 turns on 40mm PVC pipe + 19.3m slop wire until 1.5m ground on a insulate support.
Nice SWR curve , 45Khz SWR under 1.5, 110Khz SWR under 2, 180Khz under 3 SWR.
28 Feb : 65turns + 19.2m sloper untill 1.5m gnd 1.16swr 1840Khz , ... So job is done with 1st version of antenna !!!
Coil should be 40-44uH and arround 500Ohms react. So theorical value est near pratical value.
I have put some 16 radials 10-20m to the tower ... seems a bit less noise on band and swr curve a bit modified.
27 Feb : so after few adjust 1.2swr 1820Khz , 68turns + 19.2m sloper untill 1.5m gnd... seems on good ways , i ll remove 2 more coils i think...
24 Feb, Sloper is QRV... on band but 1.9 swr 1850... Z:27Ohms
1795Khz 1.1 swr Z: 41 but snow is falling , hard job to climb on tower remove 2 coils... you can see on Right picture the "blue coil" ...
20 Feb 16h 00 : So antenna is on tower , I ve begin with 80 turns on the coil @14.5m gnd and sloper until 1.5m gnd :
80 turns with 1.5mm2 on coil : 1620Khz / 1.2SWR + 20m slop
75 turns on coil : 1700Khz / 1.3 SWR + 20m slop
So now need to found the good compromise with numbers of turn in the coil and lenght of the sloper wire to change Z and X.
I will try 72 turns and cut 50 cms of the sloper ...
RX/TX gain is there, i ve done a french QSO on 1843Khz with ATU of the 756P3 cause Z is 13 Ohms ... so 3.2 SWR with 1st mounting.
I ve found the original design of wd8dsb in a Mars 1998 QST(ARRL) and the idea was great ; have an antenna to be qrv on Top Band when you have not a lof of place but a 12-15m tower with beams to put a 20m long sloper... So i've redesign the coil on bigger diameter , it my my "1st Prototyp" ... CAT IS NOT INCLUED !!!
Updated 28th Sept 2013 11h01z - @ f4azf.com