I love wire antennas . I live on a big enough place to experiment and believe me, I do. I am not nor do I profess to be gifted in antenna theory or electrical engineering. I am a lawyer but to me, "fun " is discovering and passing on those discoveries even though they are not new.
This "SLOPER" antenna has enormous utility for small lot homes and even HOAs if you have a single 30 foot mast or a tall tree, It has a big advantage over the real estate used ,for example , by an inverted VEE. It uses only 1/2 of that space. It sounds too simple to believe. It is the inverted VEE with one side vertical. , so here we go.
It is a one quarter wave wire sloping wire at about 45 degrees and fed at elevation. Mine is on a 35 foot mast. It slopes down to a tie off post about 9 feet off the ground in the primary desired direction of the lobe you want . On the ground side of the feed line is a "counter poise" It drops down almost vertically from the feed point. The counter poise is approximately 1/4 wave but it can vary a lot according to my experiment. The antenna is tuned on the sloper side for resonance. It can be fed with 50 ohm coax . 1:1 balun is nice.
But what I did was some what innovative. Mine was cut for 30 meters . So the radiator had about 25 feet and the counter poise was 25 feet. But what I did was to go for multiband using 6 feet of 450 ohm ladder line at feed point, then a 1:1 balun and then to 72 ohm RG6 ( great stuff) to the rig.
Now the RBN on this antenna was astounding ,once I got it tuned which depends ,as you know, on soil and height and velocity factor of the wire used. Mine was size 14 insulated multi-strand copper clad aluminum. So my length for 30 meters on the quarter wave was closer to 26 feet. If you can't trim or add for resonance to a wire antenna , then you shouldn't be doing this.
I was able to compare it to my 40 foot vertical which is a great antenna on 30. It showed a forward gain to the north east of 3 to 7 db s/n over the big vertical. The sloper definitely had some nulling on the back of 5 to 10db S/N compared to the vertical and then ran pretty even with the big vertical in all other directions. The reason I think it proved stronger in the direction of the slope is that the counterpoise acts as a reflector. In fact, I went 5% longer on it on that hunch.
But, DAD GUM That is simple and that sloper works,
Remember , I went multi band with the ladderline , Let's see how that worked. 160 and 80 failed ,of course . 40 - great!! In fact it is more resonant at 6.8m MHz ( flat) than 10.1 MHz 1:9. WOW!! See that 6.8mhz?) I compared to my big vertical and the sloper was better between 1 and 8 db s/n on 40. that was late afternoon and I need to check again but wow. 20 not good. 17 !! worked fine with auto tuner!! . 15 meters -- great. 12 meters -- with auto tuner !!, 10 meters-- with auto tuner! and 6 meters resonated at 50.450 auto tuned ok near by. NOT BAD. I think there is a radiation factor on the ladder line I did not anticipate . If you add the ladder line, 6 feet per side , as radiator added to the 26 feet sloping you get 62 feet , very close to 1/half wave on 40 . I now believe it is better on 40 than 30!! Let me tell you ,my 40 foot vertical rocks on 40. My phased verticals rock also. This thing is beating them in the direction of the slope significantly. In RBN tests I see as much as 8 db s/n difference. Conversely the vertical out performs by about 3 db S/N in the opposite direction of the lobe on 40 meters . Again the 10 MHz test show the same thing with higher SWR than expected. As you can tell this is an ever changing blog but this thing may have gain. I think the vertical counter poise IS a reflector!! If so, we could be seeing 2 element type forward gain of 4.5 to 5 db. Now that I understand the rf is using the ladderline above the coax I have visions of sugar plum pie.
Final tip. Keep the counterpoise away from the coax. If it is too close it will not work. I pulled mine down and away about 10 degrees from vertical.
I have since built 3 other 40 meter slopers all without the ladder line . They are great. Do inverted VEE and go vertical wth one side. So simple. You wont believe the rbn response verses your dipole at 35feet. If you have a tower above 60 feet, you are nuts if you don't do this for 80 meters.
I really have to laugh at these commercial multiband antennas for hundreds of dollars when you can slap this up for next to nothing. I have beams and other wire stuff up but this thing has real potential in tight spaces. You can design it for any primary band and with the ladder line in there, you will get multi band resonance and close enough on some bands to Auto Tune. Good luck and let me know how it goes. 73, W5ZO, Mike
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