Remotely Tuned 135' Attic Doublet

After owning three homes, raising two daughters, and finishing up our careers, the XYL and I decided to downsize into a townhouse.   That was many years ago.  Neither of us would consider trading our free and easy lifestyle for the drudgery of home ownership at our ages.  Takes too much time and too much money.  That's for the younger folks.  The downside of townhouse living is the presence of CC&Rs that frown on outside antennas. Surrender was not an option!  Adaptability and flexibility and maintaining a positive attitude were options.  
 
Antenna theory books are full of conventional wisdom.  They are so full of wisdom, in fact, that sometimes they can be counter-motivating.  If someone tells you, "it probably won't work" you may be inclined to simply accept it. Similarly, the Internet, while a potentially fruitful source of great information can also be a source of much opinion and misguided advice.  
 
I look at it this way: a) electrons can't read and b) they travel at 300,000,000 meters per second per second so at least a few are going to escape!  I choose to read for understanding and then make my own practical decisions about how to best corral that tumbling electrical and magnetic field. 
 
I've tried many stealth antennas, both commercially made as well as home brewed. Some were verticals and some were horizontals. They all shared some common features: they were all outside, they were all "temporary" so they could be taken down, and they all worked "OK."

Now let's define "OK." To me, "OK" meant they loaded up and I made contacts including good DX. I could have stopped here. But there was a "Not OK" aspect to all this.

Now let me define "Not OK." What was "Not OK" was the pressure I felt having to hide my antenna as well as hide myself from my neighbors and the Homeowners' Association whenever I wanted to work on them. Hiding them meant using very thin wire and generally having to be satisfied with end loading. This presented RF ground challenges, especially since my shack is on the second floor. Yes, I was permitted to put anything I wanted on my rear deck as long as I took it down when I was finished operating. This is very inconvenient and leads to one inevitable conclusion: I'd be likely to do less operating and the spontaneity of just flipping a switch and getting on the air when the mood struck would be ruined. Living here in New York, we are subjected to some pretty harsh winters. Who wants to go out in below zero conditions to re-rig an antenna? Finally, what better way to invite all the neighbors to complain about RFI than to advertise with a big chunk of aluminum on the deck?

This is when I turned to my attic. I owned the attic. I could do whatever I wanted there, in privacy too! And it never got wet in the attic, never snowed up there, and never dropped below freezing. And it was 32 feet above the ground at the roof peak. Hmmmm.......

When experimenting with attic antennas, it really does help to have an antenna analyzer.   I'd be lost without mine.  Any attic installation means dealing with the specific environment up there (capacitance, etc.), so all bets are pretty much off when evaluating all those design parameters generated by extensive testing in free air and a 1/2 wavelength or more above the ground.
 
A good first step is to just go up into the attic with enough light to see what you are doing, sit down on a floor joist, and think it through.  Look at your surroundings with a critical eye.  Bring a tape measure and something to take notes on with you.  Don't just focus on the "negative" aspects of your attic but see how many "positive" things you have going for you also.  In my case, I was very pleased to discover that my attic had no aluminum foil insulation anywhere, there was no AC up there, and the plumbing vents were all PVC.  We just had a new roof installed and there is nothing metallic to worry about in that regard.  Because of the architectural features of our townhouse my horizontal gutter runs are extremely short so no apparent coupling problem there.  There was electrical wiring up there, of course, but again the runs seemed to be short and it was all below the attic floor.  I used a GPS unit to establish my townhome's "heading" and was super-pleased to see that the "long" part of the attic (where most of a standard dipole's radiation pattern should head out for far away places) was northeast/southwest.  Looking at my azimuthal equidistant projection World Map, I should favor Europe on one side; New Zealand and Australia on the other side.  Finally, I measured the distance from the ground outside to my roof peak and came up just short of 33 feet.  Also, I'm on elevated terrain and the electric service is underground.  All things considered, not a bad deal!  I brought an AM/FM portable radio up there and tuned around, looking for indications of RFI and evaluating AM broadcast signal strengths.  Seemed like a surprisingly clean environment!

I initially decided on 44 foot doublet, then 66 feet, then 88 feet, then 102 feet and finally graduated to a full 135 foot doublet managed by an SGC-231 auto-coupler.   RF ground would not be a problem then and I could have multi-band capability.  One antenna for all seasons!  The "perfect" solution for an "imperfect" environment.  I mounted it very near the roof peak as a flat-top.  The first 24 total feet go straight to the ends of the attic, then I turn ninety degrees and drop straight down for 10' on each side giving me a vertical component to my signal.  Then, through a series of 45, 60 and 90 degrees turns I stuffed the whole darn thing in my 24' wide attic.   I'm very, very pleased with my antenna!  The auto-coupler needs a minimum of three watts to kick into automatic tuning and my model, the SGC-231, can come up with over four million solutions.  I can work all bands from 80 through 10 meters, including WARC, with SWRs that range from 1:1 to 1.4:1.  For operations with the KX1 or at QRPp levels with the KX2, I just use higher power to get the autocoupler to make a match, then reduce power or switch to the KX1. 

The main point I want to establish here is that less than optimal antenna installations do indeed work.  If you are a CW op you will soon realize that you are NOT at a great disadvantage with respect to normal everyday operating.
 
Next point:  Less than optimum antennas and QRP are not mutually exclusive.  With QRP every contact is an adventure and my adventures with my attic antenna installation include QRP WAC, WAS, DXCC, contests, sprints and lots of good old ragchewing.  I've had more fun than I have time or space to tell you about!
 
Take a look at our retirement townhouse.  Most people would probably think "you can't get a decent signal out of there, especially QRP!  Oh yes I can!!  I've learned to listen carefully, zero beat accurately and  I took the time to learn something about radio propagation.   I've broken many a pileup because my timing was good and I was precisely where I needed to be, while the other guy was perhaps 100 Hz off.  It doesn't take much to lose out but neither does it take that much to win if you are the master of your rig and somewhat competent in QRP DXing.  Forget about S units and all that stuff.  You'll be down a couple of them from a 100 watt rig and if the 100 watter is only working Europe at S2 you haven't got a chance anyway.  Either turn on the amplifier or go watch television, start a new project or find a better band.



Yup, that's our little retirement townhouse with the American Flag flying.  The attic is only 24 feet across.   Instead of accepting the cynics' viewpoints, all of  whom claim to have professional insight, why not just try it and see.  You may be pleasantly surprised!