Hi all Topbanders,
I would like to do a feed back on my Half sloper for 160 with original design of Don, WD8DSB that I ve change coil dimensions. Since February 2013 i use an Half sloper for 160m to have some tests before replacing my Inverted-L. Result was that I had both ants during few days ( I m barefoot 100w) and also during TX5K expedition and result was that once my qso on 160m done, I ve remove quickly the Inverted-L . 1st prototype was Done with 64 Turns on a 40mm pvc pipe with some 1.5mm2 rigid copper-wire used for electricity and slop wire is 19.5m long and until 1.5m gnd. Feed point at 14.5m ground on the tower with a trolley system to lift around 110kgs mast with a 3elts steppir + 2 elts 40m beam (7.3m boom) + my 3wl 12eltsVHF at 19.5m gnd (and also a wire dipole for 80m at 14.5m gnd). Some pics of tower and situation are on my website. I use around 24 radials to the tower, mix between 10-20m longs. (When I m using 1 of each ants on the LDG switch in the box on the top tower, all other ants are grounded.) Results are : 63 turns (around 17cms long coil) of 1.5mm2 on a 40mm PVC pipe (Around 9.5m of wire to form the coil) + 19.50m slop wire ; Fo 1834Khz SWR 1.5 Z34 R33 X9 . 120Khz SWR under 2. Now using some 2.5mm2 copper-wire (Around 10.5m of wire to form the coil) + 19.50m slop wire Results are : 65 turns (around 22cms long coil) ( I ve add some to have better Matching); Fo 1840Khz SWR 1.22 Z43.5 R43 X6 . 110Khz SWR under 2. So I think to add 5 more turns on the loading coil to have a matching near 50Ohms. I ll give result later. I m very surprised by results, there is not a real directivity in the sloping direction , I think that radials correct this. I have read that many people don't have good matching results or not a real resonate Frequency with this kind of antenna. I think here with the big beams, it act as a good Cap Hat and permit me some nice results. Now how can we qualified this antenna system ???!!! It Seems to work as a good vertical with Cap hat . If somebody also using this antenna . or have modeling it ! Best 73's de Damien F4AZF _________________ Topband Reflector