160 meter "Half Sloper." with radials

I live in the country with 2 acres at my disposal . But I didn't want some big monster antenna on 160. In the 1990s I bought a W9INN Half Sloper with a 160 meter coil. It was a very simple concept. You take it to the top of the tower but under your 3 element beam ( which creates capacitance on the grounded side). Then obviously you load the center of the 50 ohm coax to the wire and slope it back down . Mine is about 66 feet to the coil ( it also works on 80 meters) and then at the W9INN coil you have about a 15 foot tag end for a nice 75 footer coming off the 50 foot tower. Much better than  a 133 foot wire but if you have room that would work.(with trimming) 
Every beam and tower (guy wires are ok) create great variable to make it fun but there is resonance at the end of your effort.Just cut and trim.
I'm certainly not the first on this antenna but I do add a rather stunning modification. The antenna can be loaded at the bottom end. in that case radials are added and it really becomes a slanted 1/4 wave vertical , W9INN made that suggestion in his instructions. The instructions  are no longer shown on line. He is an SK.
My thought was-- what if I put radials at the base of the tower to cut ground loss. It was amazing. My 160 meter signal was much better. I worked 7 new countries in Europe in one night with 350 watts on cw (that is my maximum output with my little AL 84 Ameritron linear because my big SB220 doesn't go there) .
I only have 12 100 foot radials out now and I bend them around the house and every which way. But get this!! My signal was better off my tribander!! ( Hygain explorer 14) . Have studies been done on this?. Look I have been a ham 53 year. I have 342 countries confirmed and 1750 Challenge band countries. I'm not making this up. When I radialized the tower with ground radials, I definitely enhanced my signal on 20,15 and 10. There is no doubt about it. Yes, it is not demonstrable, it is anecdotal. . I have a friend ,NM5Y, who has noticed improvement when he radialized his 160 meterL offset from his 90 foot tower with his Steppir beam up there.  . This needs field testing which I will not do but I pass it on for further testing. and thinking. Something is happening which I speculate is LESS GROUND LOSS of the radiated signal.But the half sloper vastly improved!!

Any way , back to the half sloper. Here is a quote from   from a reflector with his Hams  experience with the 160 meter half sloper.

"I run a 68 foot half sloper (1/8 wave length on 160 meters) mounted on my 40 
foot tower, and really have a blast on 160 with it.  You can see my antenna 
in the March 1998 issue of QST.

Here are a few different lengths for your sloper, and a few different coil 
locations.  Efficiency is not as good with the coil at the feedpoint, but I 
found it very convenient to place it there for my situation.

I calculated the values below using 14 gauge wire as your sloping wire.  The 
formula I use is right out of the ARRL antenna handbook (Limited Space 
Section).  The handbook also has a chart that yields similar values.  I 
calculated the antenna for 1.8MHZ.  You can just shorten the end of the 
sloper to make it resonate up higher in the band.

For coil at feed point :
                                    Coil                    Coil
Half sloper length        XL (ohms)             L (uH)
80 feet                          376                       33.25
70 feet                          484                    42.80

For coil at mid point : 
                                   Coil                     Coil
Half sloper length        XL (ohms)             L (uH)
80 feet                          731                    64.6                    
    
70 feet                          927                    82.0

Let me know what kind of coil form you want to use (diameter, gauge wire, 
etc.), and I can give you some different winding combinations for the coil.

I had no problems getting my 160 meter half sloper to resonate, but the half 
sloper is dependent on many factors such as ground, top loading on the tower, 
etc, so be patient.

I am sure Tom (W8JI) and many of the other big guns on 160 meters laugh when 
they see such designs for antennas.  Nevertheless 160 meters sure is a fun 
band and I recommend putting up anything that will get you on the Top Band.

73's
Don Kirk (WD8DSB) 




Don,s opinions and experience are very close to my own. 
You can build your own loading coil,
There are numerous articles and internet articles on the subject. 
This is not rocket science. Good Luck!!