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Home A 160 Meter Vertical Buddipole Antenna Experiment

Moleculo

Ham Radio Nerd
Apr 14, 2002
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I live in the Los Angeles metro area on a small lot but have wanted to try out 160 meters for years. I have considered building or constructing various types of antennas that will fit on the property and even purchased a coil loaded sloper that I was going to suspend from a palm tree in my back yard. The palm tree was taken out because it became a hazard to the power lines that run along the property border in the back yard, so that plan was gone with it.

I've had a deluxe Buddipole kit for years, which I use mainly while RV'ing in places that won't let you put up wires. Last year I was looking for my Buddipole low band coil for 80 and 40 meters and when I couldn't find it, I assumed that I loaned it to someone and never got it back. I ordered another and of course, promptly found the one I already had. This led me down a path trying to figure out what to do with two 80 meter Buddipole load coils...and the 160 meter Buddipole vertical experiment was born.

My idea was to stack the two coils to create a pseudo 160m coil. I stacked two arms on the versa-tee and then the two coils. Then I used a 12' MFJ telescoping whip on top of the coils. I ran a single 160m 1/4 wave (roughly) ground wire out around the property for counterpoise and hooked up the Buddipole Triple Ratio Switch Balun at the feedpoint using the 1:1 setting. Using a Rigexpert AA-600 was absolutely critical for helping me understand the tuning of this arrangement. I figure that stacking the two inductors might cause them to interact in unexpected ways, but was hoping that the proximity of the two would make them act more like one big coil. I was wrong about the latter.

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Ultimately what I found is that I could adjust the lower coil tap to find the best SWR on the frequency I wanted, and then adjust the top coil to affect the SWR curve and bandwidth while making the SWR dip even more. I expected that the bandwidth for a low SWR on this band would be very narrow. Making small adjustments and then sweeping with the analyzer helped me quickly understand how to adjust and it wasn't long before I had something reasonable. Next I decided to replace the telescoping whip to get more metal in the air, so I took it off and put a Chameleon shock cord whip and extended base on top of the load coils to make the whip a total of 17' above the coil. I extended the Buddipole tripod up just a little bit to get the coils about roof eave height, but not so high that it would tip over. The antenna is sitting right outside my shack so the coax run is less than 20 feet.

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A quick retune of the coils, a bit of shortening on the ground radial, and I got an SWR of 1.8:1 at 1.915 Mhz. The antenna is under 3:1 SWR between 1.860-1.945 Mhz.

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The 160 meter band isn't that wide, so the tuner in the Elecraft K4D easily tunes up the antenna at any frequency I've attempted. With such a short coax run, the coax loss using the tuner in this manner is small. So the real question: Does it work? Yes! Obviously this not a very efficient antenna. The noise floor in the big city is HUGE. In the short time I've played with it at night, I haven't come across many strong SSB stations, but I've heard a few weak ones...I will continue to listen when I have time on the weekends to see if I can make some phone contacts. I decided to try some FT8 - there is quite a bit of activity there. Currently my 100 watt station is heard better by others than I can hear - likely due to the high noise and local interference. But I have made more contacts than I expected in North America.

Here's a screen shot of my transmit activity last night and the stations that heard me over the course of a couple of hours:

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I'm not done experimenting with this antenna - a local ham is gifting me a Chameleon cap hat that I am going to integrate to see if I can eliminate the top coil. I will also experiment with different RX antennas while using the Buddipole as the TX antenna. When I started this journey, I googled around to see if anyone had come up with a way to use the Buddipole system on 160 meters and came up empty. I'm pretty happy that I was able to accomplish even this much, so stay tuned while I see what else I can do with this setup on 160 meters on a postage-stamp sized lot in the L.A. metro area!

Edit: See Part 2 where I add a capacity hat.
 
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Good luck with the project M. Hopefully you will find some friendly regional locals who you can chat with. Here in Dixie, 160 is even "worse" than 80 where all the regulars have full legal limit and if you can't knock each other over the head with a 20db over 9 signal .... then you're written off as an unworthy-unwashed. I have a full sized antenna but only the 100 watts with the rig so unless I'm meeting some locals friends on those bands by pre-arrangement I mostly don't bother with it. And this make me sad - the Elitist attitudes on the part of so many hams. Same with a lot of DX on 20M.
 
Tim,
What configuration was this wire in and how high?

Thanks,
Jim

It's attached at the feedpoint - in one of the pics you can see the green wire attached to the Buddipole VersaTee. From them it just slopes down to the ground and is laying on the ground from there. An elevated radial would work better but there isn't a way for me to accomplish that at the moment.
 
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It's attached at the feedpoint - in one of the pics you can see the green wire attached to the Buddipole VersaTee. From them it just slopes down to the ground and is laying on the ground from there. An elevated radial would work better but there isn't a way for me to accomplish that at the moment.
I’m guessing it isn’t straight. How many bends/turns in it?
 
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Very interesting! I had recently posted about doing something similar, only with an Imax 2000 and using a coil. I didn't get much feedback.

73,
Brett
 
Very interesting! I had recently posted about doing something similar, only with an Imax 2000 and using a coil. I didn't get much feedback.

73,
Brett

Until I tried this, I wasn't able to offer much of an educated opinion. I'm familiar with the matching network in the Imax; I think you would have one heck of a time getting a setup like this to work with an Imax on top because I don't think it would have the range of adjustment needed. The coils I'm using are 80 meter coils...look where I had to tap them. There can't possibly be that much inductance in the Imax matching network.
 
Until I tried this, I wasn't able to offer much of an educated opinion. I'm familiar with the matching network in the Imax; I think you would have one heck of a time getting a setup like this to work with an Imax on top because I don't think it would have the range of adjustment needed. The coils I'm using are 80 meter coils...look where I had to tap them. There can't possibly be that much inductance in the Imax matching network.
Yeah, I hadn't thought about that matching network... I have plenty of end fed stuff, just thought the advantage of the antenna design itself lended itself to pretty easy assembly in the field. Not heavy, break it down and toss it in my truck bed. I guess it'll be relegated to 10-11-12 meter use.

Please keep us posted on your setup!

73,
Brett
 
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Very cool project - thank you for sharing your data.

At a recent field day, we set up a remote 160m inverted L (top-loaded Marconi) - 35' vert and 125' horizontal (strung up in the trees with insulators and paracord) and it performed surprisingly well. At 100W SSB at the transmitter (TRP was calculated at ~15W while EIRP was ~45W) we were able to make several QSOs throughout New England. The farthest was Sea Cliff on Long Island.

Against a 5' copper pipe driven into the ground near the transmitter - the inductance needed for a match was on the order of 25uH - so a conventional (beefy) tuner could just provide the match. It also tuned easily on 40 and 20m. Not bad for 160' of wire and a copper pipe !

160m is fun, but "Wire Weasel" has a valid point - it can be tough dealing with some folks in the "Gentleman's band". LOL !
 
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