My bad. I missed Ham Radio Field Day.
It was last weekend. As happens the last weekend in June each year, amateur radio operators (include from our club in town) and my buddy The Major‘s club is up in the Seattle area; he and some buds headed for the hills and remotest of places. From which the contest called Field Day revolved around how many contacts, in how many states and countries, a small team (3 operators) could rack up.
The Major’s crew was ensconced on a trail-head road and parking area, a quarter mile, or so, off to the side of US-97 that goes over Blewitt Pass in Washington State. From there, an electrical engineer, a retired three-letter agency fellow, and the Major made more than 400-contacts, talking to almost three-quarters of all U.S. States and oodles of foreign countries.
Me? Ranch work.
But, with luck, things will improve as this morning (or as time permits) I plan to hoist – and test – my latest hare-brained idea. I call it “Super-Antenna III.”
Most of my enjoyment of ham radio comes from Morse code. The collection of confirmed exchanges and chit-chatting at 15-35 words per minute, “copied in your head” is a marvelous way of communicating. When the shop is cool enough, I can listen to a Morse net and hear people’s comments from all over the country and beyond, while remembering not to saw off my fingers.
On the whole, Super Antenna-II has been doing great. I wrote up the basic antenna back in May (here). But, it wasn’t a week later that I decided to model (and install) an additional wire on the long side of the antenna. Wrote that up here.
Life marches on, but the other morning under the “Mad Scientist’s light-feeding of brain” a question began to pull at me. “Why did you ONLY ADD ONE wire, George? Didn’t it occur to you that another wire – or more – could only add to performance?”
I’m hard on myself that way. When the “little voice” begins denigrating me for failure to pursue the obvious, I strike a deal until time permits. The voice shut up…until Wednesday.
Peoplenomics was done, we had moved to cash with our play money, and with Peoplenomics being only charts this weekend, lots of work called in the shop…
“Hey, Fatso! What about that additional wire modeling, you jerk?”
Reluctantly, I gave in.
Updating the Model
This was crazy. How could I possibly improve (e.g. “get gain”) on the simple (what turned out) to be an 88′-by-84′ antenna, fed with open wire feedline by adding one additional wire (another 88 feet, spaced 6″ from the other 88-footer”? Yet, antenna modeling software says here’s the basic 88-84 (*two wire) performance on 20-meter:
By the 6.55 db is over a dipole which has 2.15 db of gain isotropic.
But look what happened with the ONE additional wire:
So we added almost one db – which (wild estimate here) would be like increasing transmitter output by 25%. But, since the antenna is also used for receiving, the gains are apparent there, as well.
My “antenna numbering system” is [number of wires on one side] – [length of one side] – [length of opposite side]. So an antenna with 6 wires, each 88-feet on one side and a single 84-footer on the other would be a 6-88-84.
Is There a LIMIT?
Honestly, I quit before getting to that answer. The reason? 88-feet of wire – times 6 runs of wire – will become a non-trival weight.
As soon as another roll of 500-feet of #14 THHN shows up, and weather permits antenna work, I’ll be building up the 6-88-84. Because? Almost 2-more db.
These six wires on one side against a slightly shorter wire opposite in a Barely-Off-Center Fed Dipole (BOCFD) configuration should return amazing long-distrance coverage, especially into Europe. This is because while the “take-off angle” is low (down just over the horizon) the antenna (azimuth) pattern is almost a cloverleaf:
To reiterate, these projections are over and above a dipole.
Are You Sitting Down?
For the next two to five years (depending on Solar Cycle Progression and how all that works out) the peak of the sunspot cycle when higher bands, like 15 and 10-meters open up, is where this “all band” antenna really swings into its own.
Look at the gain and pattern on 21.1 Mhz, for example:
Now, pencil out the power, assuming you like Morse code and have 1,000 watts of output going into a dipole.
Each 3-db of antenna gain, effectively doubles field strength at a distance. On 15-meters then, 3-db over a dipole turns 1,000 watts into 2,000 watts. And when you double again (6-db) now you’re up to a 4,000 watt ERP. And again to 9-db? Now we have an 8,000 watt ERP. And once more? 16- kilowatts of ERP.
Then Reality Intrudes
All sounds phenomenal – and even the simple 2-88-84 I’m running now is neck-and-neck with where my 3-element beam was performing prior to the antenna trap static/lightning(?) event. (On certain antenna headings.) Could I just keep adding the wires? Maybe.
A fellow on Youtube (“The DX Commander” over here) has a good overview on this antenna stuff for newbies.
But here’s where the limits of antenna gain become apparent.
Say you walk into a room with a “candle light” – you can see all over room, right?
Now, you put the same number of lumens into a flashlight and while you won’t be able to take in the totality of the room, there will be dandy vision where you want to look (and aim).
The LIMIT is when you further reduce beam width to something like a laser pointer. Light coming out the ying-yang, but unless you happen to one to look at one tiny spot then best over-all results will come from a flashlight. Following along, here?
Antenna that work well for DX (long distance) operate at (or below) a 20-degree take-off angle. But the trade-off is that state-side, your signal may not be particularly impressive. When bands are closed, higher take-off angles closer to (near vertical incident sky waves) [NVIS] work best. Which is why the take-off angle of the 2-88-84 on the 40 meter band (about 60-degrees) and virtually straight up (90-degrees) on 80-meters, make it a fine antenna for real all-band operation.
And when the 10-meter band “wakes up?”
As you can see, the gain is capped, but the take-off angle has come down and this thing should be a smoker. Provided, of course, we don’t see the Sun “go Maunder” on us.
The Super-Antenna-III has a drawback in that it REQUIRES a super high-quality antenna turner with a balanced line output. The open wire (window line) I use is #14 and is available from The Wireman. I keep a couple of vintage Johnson Kilowatt Matchboxes around.
There are a lot of compromises in wire antennas. Here’s a dandy video if you’re not into antenna modeling:
One note here: The gain figures cited in this above video are dbi. Which I discount in my analysis. So where he quotes 9.(whatever) db of gain for a certain dipole, that’s really 6-or 7 something when using “dbd” (db compared to dipole) notation.
If you’re like to experiment with my model, here are the parameters:
Have fun with it!
One of our readers (William at the Radio Ranch) suggested we try to meet up. So I will be hanging out from 14.030 to 14.040 on Morse (CW) at 2 PM Central today – callsign AC7X – and yes, I slow down to whatever your sending speed is…
Have a great 4th!
Write when you get rich,