Topband: Half sloper 160m wd8dsb studies and feed back

[Damien F4AZF]

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