Sunday, September 13, 2015

Suburb Antenna

The "New Carolina Windom" in North Carolina

My location is in a typical new-construction, American suburb and doesn't allow for ideal antenna solutions.  My subdivision was built on a field previously growing tobacco, beans and cotton, depending on the crop rotation.  So when the house was built (2002) the tallest point on the property was the peak of the roof.
Arial view of QTH as built
There were a couple of sticks in the front yard about 8ft tall that the builder called trees.  I wasn't licensed as a Ham yet so I wasn't in the mindset where I'd hang an antenna. 

By the time I was licensed as a Ham some things had grown up around us but they were mostly other houses.  The trees just hadn't grown much in 5 years.
QTH at the time I was licensed
I started off with a couple of attic antennas.  I first had a 20m Carolina Windom and a Tarheel Screwdriver in the attic.  The Little Tarheel would tune 40 but my counterpoise system was poor so it didn't perform well.  The Little Tarheel screwdriver antenna actually performed better on my vehicle working European stations on phone band while mobile than in the attic.  The 20m Carolina Windom in the attic made contacts but electrical noise from the proximity of wiring was pretty bad.  I tried a number of other antennas in the attic and in general none worked very well.  I needed to get an antenna outside. 

I don't have strict covenants but towers and push up poles are prohibited so I need to attach a wire to the house in some way. The tallest point on my house that was semi-accessible was the peak of the roof on the Southern facing side.  I had a window in the third story attic just under that peak.  At the time I didn't have an antenna tuner so I read about multi-band wire antennas that supposedly didn't require tuning for multiple bands.  A fan dipole could have been a good choice but I had to have the antenna in an inverted V and there was nothing of height in the rear to keep the lower elements of the fan far enough above ground.

I settled on the "New Carolina Windom" 
Schematic for New Carolina Windom
This antenna had a number of advantages for me.  It is multi-band and theoretically doesn't require tuning for 40m, 30m, 20m and 15m.  I ordered a 4:1 balun and a line isolator, wire, rope and coax and got to work.  Since I my antenna had to be inverted originally it turned out to not tune as well as I'd like.  The antenna tuned under 3:1 on all the bands and under 2:1 on 40m in the phone segment.  I used the antenna for a couple of years back when I was doing QRO phone and digital modes until a mishap brought it down and it laid under the bushes up next to the house for 6 years.

Now where did I leave that antenna?

When I became interested in QRP and CW again a few weeks ago I had a portable end-fed long wire but nothing for the home QTH.  I remembered the Windom buried under the bushes.  In the six intervening years my trees had gained a bit more height so it was not quite as inverted as it used to be.  Strangely now that the long segment (41ft) is more or less flat-top and the short segment is inverted it tunes 20m under 2:1 and 40m is now 3:1.  30m SWR is now about 6:1 but I have a tuner to handle that and it's been quite effective on 30m QRP.  Actually there is one more change. The original vertical coax segment of 10ft was unusable after all those years under the bushes and I used the only other ready made, short coax segment that I still had amongst my cache of antenna supplies. That vertical radiator segment is now 12ft rather than 10ft so that may be the reason for the tuning difference.  This is certainly not a well designed experiment.  

I'm confident that if I took the time to trim the wires to proper length and get the vertical radiator segment the correct length it would tune under 2:1 in all the bands it's designed to operate on but for now I prefer spending my time making contacts.  When it cools down here in NC I'll do some more antenna work.

My point is that this antenna (even with the misconfiguration) seems to work fairly well on 40m, 30m and 20m  I've never made any contacts on 15m with it but I don't hear much on that band.  

It outperforms my 40m doublet at the same height (~25ft) by 2S-Points from some limited tests and is definitely quieter on receive.  I've worked Chile, Spain and Eastern Europe with QRP CW.  The wires are not in-line as there is about a 15deg angle toward the South.  I have worked Utah in the US from NC but that's as far West as I've gotten on CW.  I tend to not stay up late enough to work the gray line propagation heading in that direction.  The ends of the antenna head West and East so that null to the West may be an issue.
I understand that anecdotal reports aren't terribly useful as some may be able to report that they've worked Madagascar using a spoon with one watt but this antenna works for me. 
Here is a view of the antenna as it lives today.  The 4:1 balun hangs from a dacron rope attached to the peak of my roof far enough down so that I can retrieve it back in the 3rd story window for maintenance and detach it (that is the extra rope you see heading to the window).  From there the vertical radiator goes to a choke.  I didn't want there to be stress on the coax of that vertical radiator due to the weight of the choke so I have another dacron rope running down that coax and attaching the choke to the upper balun as stress relief for the coax.  The long segment of the New Carolina Windom heads off to the now 25 ft tall tree in the from yard and the rear element slopes down to a bean pole in the garden behind the house.  From the front of the house the antenna is not visible and my next door neighbor who can see it doesn't seem to mind.

View of the balun and choke at the end of the vertical segment

So if you're looking for a reasonable performing multi band antenna and you need one segment shorter than the other based on your QTH restrictions I can recommend the New Carolina Windom.

--- UPDATE Nov 1, 2015 ---

Since this review I replaced the 40m New Carolina Windom with a standard 80m Windom (OCF Dipole) at the same position.  It is resonant (requires no tuning) on 80m, 40m, 20m and 10m.

80m Windom 4:1 Current Balun
Long side of Windom (89') attached to fiberglass pole @12' agl
So the 40m Windom is no-more.

That's all for now

So lower your power and raise your expectations



  1. Are the fiberglass poles the army surplus types?

    1. Yes. I got a bunch of these for free. They deteriorate if left in the sun so they can't be used as a permanent solution without painting them to make them UV resistant.