Prepping: Winter Ham Radio Antenna Plans

In just a few short months, winter will be upon us.  With it, ham radio comes into its own.  Nightime propagation in winter can be spectacular on the lower ham bands; 40, 75/80, and 160-meters.  These correspond to the 7-7.3 Mhz, 3.5-4 MHz, and 1.8-2 MHz bands.

During summer months with longer hours of daylight in the Northern Hemisphere, even at the lows of Solar Cycle 24 (going into the upswing of Cycle 25 in a year or so), the maximum useable frequency (MUF) somewhat dependably rises to 15 MHz during the daytime.   At frequencies above the MUF, signals are radiated into space, while more than 5-10 MHz below the MUF, there’s not atmospheric (F-2 layer ionospheric) “bounce” – what the CB’er’s called “skip.”

When the Solar Cycle is at it’s peak (as it was around 2011-2013) the MUF was even higher, sometimes reaching above the six-meter (50-54 MHz) band.  At 14 MHz during this bonanza time, I worked many stations in Europe with a 3-watt, home-brew QRP (low-power) CW rig.  Since the Cycle is bottoming now, I’m back to high power; linear amplifiers and a renewed quest for the perfect antenna.

Is There a “Perfect” Antenna?

Like boats, sports cars (and relationships, lol), it depends how much time and money you are willing to invest.

A couple of truths about “Cycle-Low” antennas:

  1. The Low Band Antennas eat all kinds of real estate.

This is because the most useful common size & type is a “half-wave dipole” antenna.  The simple formula for antenna length is (roughly) 468/frequency in MHz.  So, to illustrate, if we design a ½-wavelength antennda for the middle of the 75/80 meter band – 3.75 MHz, it means the antenna should be approximately 124.8 feet in length.

Because a di (meaning two) pole antenna consists of two quarter-waves (in this case of 62.4-feet each) the first complication is the antenna feedline must be attached at the mid-point.  99-times out of 100, there’s a house in the way.

The second problem?  The Perfect antenna would also be a quarter-wavelength above the ground over its entire length.

About here, we run into other stumbling blocks, not the least of which is finding 60 foot- high support poles.  Especially in a city, especially where there are neighbors, and views, and Homeowner Associations, and other “obstacles to the hobby” like that.  Insurance companies aren’t keen on things that can fall on some else’s property.

Still, the proven dependability of the inverted-vee antenna – essentially with a single pole in the middle sloping down to about 10-feet (or less) on each end, is a workable compromise.  With this kind of antenna, unlike the usual dipole radiation pattern where the maximum power is radiated at right-angles to the wire, the inverted-vee configuration’s maximum horizontal lobe remains at right-angles, but the vertical component of the signal become end-firing.

Inverted Vee antennas are a great choice for US hams.  You simply orient the antenna wire so it points at the “other corner” of the country; perpendicular to the wire.

A California station might run their wires north-northwest to south-southeast.  This would position the horizontal lobe into the Northeast corridor.  The vertical lobe would end-fire, giving a great “look” into Russia and east into China/India and Japan via the north (magnetic) pole.  KL7’s (Alaska) ought to be good, too.

How Can a Dipole Be Improved?

The simplest answer?  Higher support poles.  Again, there comes a practical limit.  Even those of us lucky-enough to have towers with higher band beams on them, still have the problem of the wire ends.

My tower is 52-feet up to the wire antenna pulley sits (and 8-feet further up to the beam).  How to position the “two ends?”

As luck would have it, a few years back I picked up a used 43-foot MFJ aluminum vertical.  This will be placed in service from the top of the carport on the south of the shop/office/ham shack building and that will result in about 55-feet  of altitude 61 feet from the tower.

The other end is being “shopped” right now.  Several good options are available.  One that gets great reviews is the 28-foot Jakite thick pole (desinged for flying kites and wind-socks) available from www.jackite.com. $70-bucks and a great deal.

Competing with that option is a higher 50-foot pole (and $239 dollar) pole from Max-Gain Systems.  This option is a bit more money but if you’re willing to put in the recommended guying, that’s certainly an attractive option because there’s no substitute for altitude with antennas! See www.mgs4u.com/fiberglass-push-up-masts/

Horse-fence, Dipole, OCF, or What?

Boy, we just opened a can of worms here!  The short summary (based only only 55-years in the hobby, lol) ranks them in this order:

  1. Simple.  They only work well on one band, though, so consider a “fan-dipole” or a “trap dipole” for multi-frequency operation.  Traps have some minimal losses – but are easiest to install and tune.  Fan dipoles might be a tad-better far away, but you could be playing with as many as 10-12 end points for five and six-band coverage.
  2. Horse-Fence dipoles get rave reviews on the ham radio sites like eham.net. Unlike a single-conductor, the horse-fence antenna uses stainless 1-1/2 to 2-inch wide electric fencing designed for farm use.  The claim is that because of their spacing between multiple conductors,, they are slightly “hotter” than a conventional antenna.  Engineers say “No…” but user’s love them based on reviews.
  3. The OCF is an Off-Center-Fed In other words, if the basic half wavelength is 135 feet, for example, the antenna is fed at about 33-percent of the antenna length.  Call it 45-feet in from one end, leaving the longer end to be stretched-out 90-feet.  Reviews tend to track manufacturer and how good the installation is.  These work best when all parts are at the same level, and less well when installed as variants of the inverted-vee.

This Year’s Antenna Projects

Somewhere in my background, I “wrote the book” for one of the major antenna tuner manufacturers.  And the late president of the company “took me to school” on HF antennas.  Let me paraphrase what I learned:

George, as an HF antenna radiates, there will be voltage and current nodes on the antenna.  If you want to have a maximally-efficient antenna, you need to use a conductor that is as large as practical.  This way, when the voltage is down – and current high – you will pick up efficiency.”

OK, sounds fine.  While it is nominally true that an antenna made of #14 copper will “handle” a couple of kilowatts (PEP), it only takes a moment to see the truth of what my mentor was conveying.

We can determine current in an antenna by using the simple formula:

Power equals current squared times impedance.  Also stated as:

P=i2r

We’ll avoid using z (impedance) and stick to r for clarity.  There’s no test here.

Now let’s fire up one of my stations…here’s a TS-590S and SB-220 linear that we can dial-back to exactly 1,000 watts CW output.  This becomes “P.

Since we know the antenna presents a 1:1 SWR at resonance (or close enough for ‘government work’), we can calculate antenna current will be using 50 ohms?

Power divided by impedance equals the square of current, so the actual current is the square root of whatever i2 is.

So…. 1000/50 = 20 0  (i2) So the square root of this is?  4.7 AMPs.

Except not quite

When we run full legal limit out, the current rises to 6.7 AMPs.

But we also know that many antennas, low to the ground at these lower frequencies will really have impedances that might be as low as 25-Ohms.

At these impedances, the current might be 14-amps at many places on the wire.  And as my mentor explained, the “snap” (current reversal) is where the radio signal really “fires from…

Perhaps, that’s why the “horse-fence antennas” work OK?  I ran to the American Wire gauge tables.  Horse-fence antenna makers claim as many as 18 conductors but it’s often cabe be smaller than 30 -gauge wire.

They key factor is wire diameter times number of conductors.  That’s because the actual radiation takes place very near the surface due to “skin effect.”  If  comparing antennas, we’d be best-served comparing wire diameter not thickness.

It turns out that 30-gauge wire is pretty thin:  0.01 inch, in fact.

But, the trick with the horse-fence design is using a proper clamping system, you might have 14-conductors which brings the total of diameters up to 0.14 inch and according to the table (online here) that’s the same total of diameters as a single strand of #7 wire.  Easily safe for a kilowatt of power.

Here Comes EZNEC

Since we keep the grown-up version of Roy Lewallen’s EZNEC antenna modeling software at the ready, it didn’t take long to find – in certain configurations of dipoles, vees, and OCF’s where there can be 1.5 db, or thereabouts, of additional antenna gain when using extremes of wire size or massively paralleled wires.

Take an OCF dipole, for example.  When I compared the model of #14 wire, and moved the wire size up to #0  (“single ought” is as big as EZNEC models as a wire size), I found lobes were the antenna “snapped out” almost 2 db stronger!

That sent me shopping.  But not for horse-fence antenna wire….

eBay to the Rescue!

I remembered from somewhere in the dusty memory banks that years ago, I had read an article about somewho who had used a spool of computer printer ribbon cable which was turned into a six-band fan-dipole.

That’s what I wanted because a db or more of gain really matters at the entreme of the hobby.

A bit more than a hundred dollars later, my role of “dream wire” showed up.

It’s 14 conductors of #16 wire.

The spool has 220-feet, so enough for a two-band fan dipole and with what kind of wire dimensions?

#16 wire is 0.0508 inches each.  Times 14 conductors gets us 0.7112 inches – so this SHOULD radiate like 7-10ths of an inch copper.  Can you imagine how efficient a 125-foot piece of ¾” copper pipe would be if you could figure some way to hold it up?  This is nowhere near as light as horse-fence.  Twenty pounds per side.  A price I’m willing to pay…go ahead and sag a bit.

What’s more, since the ends are the only exposed metal, it should be simple to put “corona dope” all over the ends and around the center insulator.  We’ll be using a 1:1 W2FMI 5-kW capable current balun in the middle.

This promises to be an interesting experiment and it shows again how much fun you can have “inventing things for yourself” in ham radio.

One Other “Big Signal” Idea…

One last point:  Most people don’t realize that low band antennas can fall way below 50 ohms.  Low antennas are often be down in the 25-ohm range though it shows up as a 2:1 standing wave ratio (SWR).  Depends on meter.  On mine it reveals as a “double dip” SWR..

A fellow in France as started selling a special balun for this case called a 1:2 balun.  You put 50 ohms in from your transmitter and the output wants to see 25-ohms.  Look for ‘em on eBay in the ham gear section.  When the XYL’s not home.

For 30-bucks, it’s the core-only: you supply the box and fittings…But are you kidding?  Deal of a lifetime!  My last “Super-antenna” (the 746-foot OCF dipole) works fine, but the SWR is habitually wrong. It has the “double bottom SWR” – a giveaway the antenna is under 50 ohms. This get the monster antenna back on track…

Next time you hear me on the air, hold up your coffee cup.  I should be able to heat it up for you…all the way from Texas!

Vy 73, ac7x  George@ure.net

17 thoughts on “Prepping: Winter Ham Radio Antenna Plans”

  1. George
    Don’t hold back! Just splurge and spend your kids inheritance on a Discone Antenna. Make it about 80 feet tall and you can transmit to just about any where without any fussy antenna switching.

    • I am with Rocket Mike..If you are not exceedingly wealthy the odds are that the kids aren’t going to get any inheritance anyway..People never consider the end of life expenses.. it usually all goes for Medical and end of life care and the vast majority end up on social programs to pay. ( has anyone really given any thought to WHY the new federal regulations are there LOL.. no psych meds, no rails or other safety measures. you can have them in a hospital but if you are end of life.. well it is your choice how you want to go all broken and battered with frail bones.. my thought it might as well even up the odds a little save a little scratch LOL). Even if you have great insurance once you are gone.. well ask anyone in a catastrophic event just how great the great insurance they have was. I have seen so many simple millionaires go out penniless its amazing.. most of the time if you are married you end up in divorce so the spouse can survive since all of the assets have to go to medical…. so I am thinking go ahead get the good antenna the kids ain’t gettin a dime anyway you might as well have and enjoy the new toy while you can..Now if your using gold leaf toilet paper.. and want to leave a little so the kids can go to Cancun and to the white man overbite or something.. then I believe you can give each of them (not sure but I think )ten grand a year in gifts that they can’t come back and take it all away from them if something happens to you in a seven year period..

  2. Several years ago, I have tried Litz wire that I had available, with excellent results for a 20m inverted V – I used 0.1mmX800 (AWG38 x 800).

    I have recently seen Litz wire AWG40 x 2000. It is used in the mining industry. it is expensive, about $3 per foot, but worth a try, when I get rich.

    WU0X

  3. Years ago when I chased DX on 80 meters, I used a quarter wave sloper off of a 60 foot tower. I ran it toward Europe. For a while then moved it to work the Asian stations. Worked pretty good for me.

  4. Here in North Carolina, it’s almost as hot and humid as where you are in the summer. Shortly, as the blast furnace moderates for the Fall, I’m finally gonna get a chance to try The Antenna Of My Dreams — an end-fed, half-wave, on 40 meters, way up high.

    Why? Glad you asked.

    To NOT have the drippy coax come dripping down either ON the roof, or dribbling down in the middle of the yard if a different pair of trees is used. (We have Really Great antenna trees here. Tall, straight, with few lower branches. Very similar to lodgepole pines.) I have a nice selection, but they ALL would drip the damn wire down in a non-XYL tolerant zone.

    So. Enter the end-fed half-wave. I’ve tried several commercially available ones, with that damnfool lossy diddle-box torroid in a box at one end — and found them all noisy, and (seemingly) not very effective.

    But! Stop and consider the much-praised J-pole for VHF. It’s essentially an end-fed half-wave, with a quarter-wave matching section at the bottom (J-poles for VHF are almost always mounted as verticals), made of transmission line, not lossy, saturable torroids, making the whole affair three-quarters of a wave long. For 40 meters, a J-Pole would be 99 feet, total length.

    Now! Instead of vertically, mount this whole combo horizontally, and use 600 Ohm “ladder line” for the quarter-wave section. Mount the whole thing horizontally, and feed with coax, now at the END, very near the tree, and with the feedpoint way up high as well.

    Presto! No drippy wire in the middle to be seen and hated by the XYL.

    The reason for the 600 Ohm line is mathematical, and makes a better match than 450 Ohm “window line” to the very high-Z at the end of the half-wave radiating section. There was (is?) a ham in Alaska (of all places) selling such 600 Ohm “him-made” line on eBay. I bought some a few months back. VERY strong, VERY well-built stuff.

    I have high hopes it’ll be a killer antenna.

    I’ll let y’all know.

    73
    Radio Ranch in NC

    • When Ure ready – let’s do a 40-meter shoot out, shall we? I’m working on a gamma match for the tower with that 1:2 balun that got in from France this week…. My bet is the multi conductor wire antenna will kill all comes. Very similar to the low-inductance ground concept on sailboats for rf grounding…big-ass low inductance were with …well, we’ll see, huh?

  5. Interesting experiment. Is the main body of the cable UV resistant? I have a spool of 80 conductor telephone cable that I want to try this same concept with. It’s a bit heavy though so I would expect a lot of sagging.

    73

    • Sagging is why God made inverted Vees – have the droopy ends toward the N pole and dx vista will open up since the vert radiation works best that way/…

    • Yeah, they sure do…but this models almost as well and it’s a dirt simple install – pretty neat – should have it up in next week or three – got a Jackite pole coming for the uphill side (26 feet) and the downhill will be about 45 with tower at 50 feet in middle or whatever it measures.

  6. “One Other “Big Signal” Idea…”

    I have been digesting this all day yesterday… and I’m curious.. could a crystal filter increase your wave reception..
    you all already know I am big in the belief of frequency and its involvement.. so consider.. you have a cheap wifi booster.. take salt water swish it around a small clear plastic tube or bottle..let it dry then put over the antenna it will either receive or broadcast better because of the crystalline coating inside on the plastic and the salt crystals act as a filter( this is one of the reasons why old radio active waste material from nuclear power plants is stored in salt mines as well) .now you would have to break up the signal to polarize the signal to increase its effectiveness by focusing.. most antenna’s are just a wire you expand the range by expanding the wire..( many antenna’s are competing for one single frequency as all of us already know we are bombarded by many frequencies at the same time from every direction and every kind each wave or a particular frequency can cancel out the others depending on the cycle EMP as an example.) if you can cover the antenna break it up.. lets say every four foot with a spacer.( use black pvc as an example.. it absorbs rather than deflect) then you can also expand your footprint by simply expanding the antenna size..disks stacked and globed( remember the old looking antenna in Frankenstein with the glass globe over the pie pans Brew haha) just a thought..also take a look at the old radio towers in Alaska HAARP.. same thing there except they are using a huge array and my thought is that they were having problems because they couldn’t control it like they thought they could.. since the signal went out in all directions at the same time that they were bouncing the signals in one direction rather than focused which would in my mind give conflicting results.. positive yet negative in other area aspects .. or as they would say in one part of the country.. YEAH BUTT results….

  7. Alpha Senior pointing SW and Alpha JR pointing NE at 36 feet high, Vertical pointing uh, straight up. Just received my Balun Designs 1:1 isolation Balun. As soon as the weather cools a bit a full sized G5RV will be at 35 feet. Ladder line from copper to Balun, Balun to CO-AX, CO-AX to AT-1000pro2. Should be fun.

    • This is where I put on my antenna modeling hat and recommend a hellatious ground system, short runs of coax and nothing but the freshest Times LMR-400 Flex for coax…

  8. I have a very high noise level on all bands of 9+. RF? I contacted power company. They sent man with am radio and binoculars.lol He stated yes you have high RF but he couldn’t locate it. What can I do? I know they can be fined if they don’t correct it. I hope this post is ok?
    If not let me know I will try delete it
    73s.
    KY4(something)

    • If you live near a power/transmission line, they are notorious sources of RFI! They behave like a long wire antenna capable of picking up RFI at one location and re-transmitting it at another. Typical powerline noise results from “leaky” insulators. Insulators picking up dust, creating a bunch of micro spark-gaps generating RFI. SINAD is a detailed measurement method used to measure level of noise plus receiver distortion. Some RFI can “slew” receiver AGC reducing receiver sensitivity. Description of SINAD can be found at,

      https://en.wikipedia.org/wiki/SINAD
      https://www.radio-electronics.com/info/rf-technology-design/rf-noise-sensitivity/sinad.php
      http://www.signalpro.biz/sinad.pdf

      It requires equipment to perform a SINAD. Typically, two identical antennas separated where they are in each other’s far field, approximately 10*wavelength. A 1Khz tone modulated signal is transmitted from one antenna and received by the second antenna. At the receiver the 1Khz tone is notched out and a comparison is made between transmitted signal (carrier only) and notched output at the receiver. It measures the RFI level and any receiver distortion due to AGC “slewing. Measurement first performed at a pristine location (min RFI) and compared with results to a noisy one. This quantifies the noise generated from external sources in the area.

      A cheap and “rule of thumb” method, is to take a field strength meter to an RFI hotspot, then perpendicular to the powerline alignment, walk out and record field strength every 10 or so feet. Graph results, if you see a 1/d negative sloping curve (d distance in ft.) you found the RFI source. If no 1/d slope curve, problem is somewhere else. If you are going to do “battle” with a power company, you need quantifiable results to support your claim.

      Typical noise factors at 50 MHZ are -100 DBW in a city and -125 DBW in rural areas (no powerlines)

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