Ure is a gen-u-ine QRQ Extra Class Ham Radio geek. QRQ means high speed Morse Code and some of us believe it enables a “direct digital” part of the brain. Extra Class because there’s no higher certification offered. And geek? You don’t need help on that part…
What is a Super-Antenna
A Super-Antenna is something anyone can make and easily deploy, costs less than $200-bucks, and has amazing performance.
Super-Antenna I, which I put up several years back with the help of my buddy “the Major” was a massively over-scaled OCF – off-center-fed – dipole. One side was 183 feet long, while the other was 746-feet in length. Huge sucker.
The best signal report I got out of it was a 20-db over S9 reading from Hawaii on the 75-meter phone band several winters ago.
While it worked great, it was something of a PITA to maintain. For one, it was 40-feet up and not in a tower. We’d rented a Genie 36-foot platform height 4-wheel drive monster vehicle to get up into the required 9-trees on the long side of the antenna path.
When the wind came up, 900 lineal feet of tree path breaking off branches transitions from rare to dead certain.
The other problem with the antenna was that during the day and evening hours, it was a dog. Not much better than a resonant dipole (that is, equal lengths of wire fed either side of a center insulator. Super low take-off angle – useless in the day when vertical take-off angles – work best on low bands.
Super-Antenna 1 also didn’t play well on High Bands. On 3.6 MHz it was a monster at night when the F2 was open. Dog during daylight hours – yuck.
Into the engineering books. Daytime, when NVIS *(near-vertical incident skywave) is in play, the goodness is touched by shooting energy up and then allowing what amounts to F2 back-scatter to cover the region of interest.
Feedlines and SWR
To summarize several months of enjoyment: 929 feet of wire up 40-feet will work great only some of the time. I screwed up by using a single coaxial feedline (LMR-400 and a 5 kW commercial balun).
The feedline length became problematic on some bands. Sure, you can “flatten” a meter reading, but in reality, there’s only ONE low-loss way to feed a wide-range antenna: With Open Wire feedline. (OK, a SmarTuner [-SGC] or AH-4 [- Icom] antenna coupler AT the antenna will work. But unless you roll with Big Money, they’re maxed about 200-watts, or so. )
Tuners are at the radio, couplers at the antenna if you want to get picky about it. Remember Ure wrote one interation of the SG-230 SmarTuner manual when he was at SGC?
The other Big Problem with Super Antenna 1 was it was mostly broadside on the low bands.
Since my wire runs southwest to northeast, I wasn’t getting into Europe worth a damn. Result? A second “dream antenna” began to take shape to address these shortcomings. Just a concept at this point. Wire is in hand, though.
OM-2’s son – ace of trees – is enroute today.
Broken Beam – Nailing Down the Specs
Meanwhile, something had gone wrong with the Cushcraft AS-4 WB 60-feet up the tower. The SWR was high and its efficiency has gone to pot.
Maybe it could be chalked up to “rain in a trap” but more likely effects of near or a small side-strike off lightning.
Spec. #1: Whatever else, Super-Antenna II would HAVE to work great on 20-meters into Europe.
Spec. #2: I was going with high-end (#14) wire for the antenna and #14 Open Wire (ladder) line from The Wireman. Product 554.
WHY? First, because Deborah ay WireMan is great to work with and their quality has never failed me. And this is over something like 30-years going back to when Press Jones wrote The Wireman book which is still one of the finest references on ham radio and commercial radio wire ever.
But the main thing is, I like nice, strong, easy-to-copy CW (Morse) from far away places. Beams break because they are complex. They have mechanical issues, statics issues, they have antenna rotator and control box issues, and they’re a 24-karat bitch to feed with Open Wire because the line needs to be kept away from the tower…
Also takes 2-3 people and power equipment to bring the tower down and put it back up.
Since I an the owner of two Johnson KW Matchboxes, getting the antenna tuned to ladder line is no sweat. High impedance feedlines have almost zero loss. Ladder line is only slightly particular (doesn’t like being near metal, for example) but usually outperforms coax. 94 times out of a hundred.
Spec #3: I didn’t want anything higher than 60-feet, the present top of the tower. We get enough lightning to scare Wardenclyffe fans.
Ideally, lower. At 50-feet, I’d effectively have 10-feet of tower-grounded lightning arrestor of sorts above the antenna if I just unplugged the radio shack via a huge double knife-switch.
Of course, there are dreams about a 43-foot insulated stick up there, fed by a coupler, too. But, again, why tempt lightning?
88 Feet of Magic
Months rolled by. Doodles. Hours of antenna modeling. Worse time sink than trying to time financial markets.
But in the end, simplicity itself is what turned out to be magic.
Yeah…not even particularly high (42-feet in the middle and 30-feet on each end) but I’ve come to have great faith in antenna modeling software to get me in the ball park.
20 Meter Performance
Want some major “radio geekness?”
There are a couple of ways that antenna manufacturers take products to market and mislead folks along the way. One is by stating unrealistic antenna expectations.
Easy to do, too. Because many antenna designers don’t design to the benchmark of the “real world” which is comparing their efforts with a simple dipole antenna. Two quarter waves of wire, fed in the middle, in free space.
Instead, they skip mentioning a simple dipole works great and “magic happens” when they are resonant. (Or when you use ladder line a/k/a open wire feeders. Yes they are different, but let’s gloss over that part.)
This is why, when doodling antennas, we ALWAYS put in 2.15 db as the reference level. Because a simple wire dipole will get you that far. Or, a good quarter wave vertical over a good ground system.
When I tell you an antenna has 4.3 db side lobes that means over a dipole.
Antenna peddlers would advertising the same antenna as having 6.45 db of gain!!! Well, sort of…
Oh, also helps to know that when you double power of a transmitter, you’re adding 3-db (decibels) and double it twice gives you 6-db or one full S-unit (strength) stronger at the far receiving site.
100 watts with 6 db of antenna gain effectively transmits 100 X 2 X 2 = 400 watts.
It also amplifies the received signal as well. (Always invest in antennas first, not an amplifier!)
Here’s what SA2 models on 20-meters, elevation view first:
As you can see, this radiates about as well as doubling my power into a dipole and then increasing it half that again. Not bad for some “dumb wire.” But, here’s the best part:
It also End-fires the major lobes. Which means, when you rotate this countes clockwise 45-degrees in your head, it points at most of Europe and Africa from Ure’s place! Hot diggity dang. NZ and Chile the other way.
OK…Take-off angle is not as low as ideal (10-20-degrees) but close enough to run with. It will be a smoker state-side for Morse work.
40 Meter Performance?
Well, about close to perfect for me. For daytime use, it squirts most of its power more-or-less up for NVIS work, like so:
Remember, the 6.32 db is above the Reference – a 2.15 db gain from the dipole. So 8.47 db of gain is how a misleading antenna huckster’s ad would “sell” this.
The nice part about this antenna is that in the 3D view, you can see how it also retains some of the broadside characteristics of the Double Extended Zeppelin antenna which was one of the starting points:
That Y axis gain runs to the northwest from Texas. The son (KF7OCD) and “the Major” are up there.
While the smaller end-firing lobes (4.3-db max) will head for Europe. This will result in good 40-meter coverage into Washington, Japan, and down into the South Pacific. With a reasonable side of Europe.
Overall, its about $1,500 bucks cheaper than updating the rotator, updating the beam, and spending another small fortune of low-loss LMR-400 coax.
Open Wire and Ladder Lines
A lot of my friends from the early 1960’s were “brought up on coax” but the really great signals always came from just a few classes of ham stations.
- Waterfront Hams: If you want a humongous signal, live on a salt water beach and work hams on the far side of the water. One of my “life changers” was flying a kite-lifted antenna out over the reef back in my ZF2HD days in the Cayman Islands. OMG.
- Hams Who Own the Sky: I know people with 150-foot (and taller) radio towers. Believe me, you can fart that high up and get 10-over signals out of Europe. The saying at myt late friend Dale’s place near SeaTac airport (with a 182-foot tower) was “20-meters never closed at Dale’s house.” (Collins S-Line including a 30-S1 amplifier helped, I suppose.)
- Hams with Ladder Line or Open Wire Feedlines: Simple fact is a high impedance feedline doesn’t have nearly as much loss as coaxial cable. Sure it takes a good antenna tuner to “make the magic” happen. But, that reminds me of a great story.
Once upon a time there was a transmitter engineer down in San Francisco at (going from memory) KFRC. Phil L, I think. He got to looking at the KFRC antenna system one day and (correctly) figured it was a fairly complex network and had to be tuned “just so” to meet the FCC’s directional antenna requirements at night.
High Q networks are sharp and don’t pass signals on one or both sides.
Thing was, the station was losing talk-power (in the form of apparent loudness) because while one sideband of the AM signal (the upper sideband as I recall) was crisp and had good highs, the opposite sideband (the lower sideband) was “cut off” and muddy sounding to him. Result? Apparent loudness was lower.
The answer? A broader T-type matching network. Made all the difference in how great the station sounded on the air at night thereafter.
Yes, Phil L. – but first rate AM radio engineer. It’s all magic.
Ever since hearing that story, I’ve been afraid of going for very “high Q” (tightly tuned) antenna networks because using wide forms of modulation (AM at night on 3.825, 3.870 (West Coast), 3.880, 3.885 on the 75-meter ham band, for example) enough “little tricks” like this can make all the difference in the world.
Anyway…I’ll let you know when SA2 is up and flying and “how close to the model” it turns out.
We now return control of your weekend to your XYL.
Write when you know what vy 73 means…
de ac7x w/ kg4yhv