Power Lines as Psuedo-Yagi RF Director Elements

Being relatively new (albeit intensely curious) to the ham radio community, I am prone to trying just about anything within reason to propagate and receive high quality RF (radio frequency) signals.

While it doesn't hurt to have a high quality "rig" (radio) to send and receive signals, it may not take long to realize that - despite having a fair or even poor quality transceiver - one can do pretty well by having a superior antenna. In my recent experiments at home, I've tried various home-crafted antennas including balanced dipoles, long wires, and some "home-base" automotive antennas.

In this accounting of my recent experience, I suggest I may be using one of the largest antennas in the world!

Countryside "Quiet"

When I get to yearnin' for some travel, nothing beats hopping into the car and going for a short road trip. As a ham radio operator the idea behind this is to "be in the clear". By leaving the city, most radios experience significantly reduced splatter, static and other spuriously generated noise common to the big city.

The countryside is not only relatively quiet to the human ears, but also on a radio's antenna.

"Curious" RF Intensity

On recent trips into the countryside I have noticed that RF gain seems to hike up a notch or two while driving in certain locations at any given time.

At first I attributed this to signal drift one may experience on certain days when there are many factors which could cause a signal to rise and fall in amplitude. However, more often than not I started to see that RF gain in certain places seemed to hold steady in spite of whatever factors were afoot. Whether cloudy or clear, windy or still, signal gain seemed to spring up only in certain places as I drove by.

Curious about this, I decided to investigate.

Singled Out: Power Lines

While driving around, I began to make mental note of where incoming RF gain seemed to rise. After driving back and forth over high RF locations several times, I saw there was only one common factor: relatively open flat space. The key word here is "relatively".

I was puzzled at first. With the absence of mountains (or even hills) - through whose saddles and canyons a line-of-sight signal could gallop through - what could possibly make this open piece of land so popular for signal propagation? Upon some further observation and thinking, it seems I have run across the answer...

Power Lines: Friend or Foe?

The one additional common factor I seemed to have overlooked in these high-signal spaces were our collectively dreaded foe: power lines.

Power Lines as the Foe

Experienced amateur radio operators know that power lines are frequently considered the bane of good RF reception.

Perched like vultures atop an otherwise serene countryside or rural landscape, power lines provide the lifeblood which keep the common American household afloat. Aside from this, we all know that many businesses (including industry) use enormous amounts of electrical energy transmitted across these gigantic buzzing wire traps.

But alongside the seemingly harmless activity of providing power to granny's electric stove, power lines wage a silent war against amateur radio operators. Ham radio buffs - both at home and operating from a mobile (car or on foot) station - pick up powerful and annoyingly loud interference from these power lines. This static noise frequently "walks over" incoming radio signals on the amateur bands, and thus keeps the intended receiver of these signals from ever hearing the message. Needless to say, power lines and the noise they produce are considered the enemy of amateur radio operators.

However, before categorically banishing all power lines off into the nether realms of RF hell, I seem to have run across a few good apples within the spoiled stock.

"Friendly" Power Lines?

During my investigation while driving about the countryside, I made a point to immediately stop exactly upon those locations where RF propagation seemed to noticeably rise. After striking upon the notion that this gain in signal strength may be associated with power lines, I had a look around.

For each location where signal strength seemed to rise across the band, I noticed that the power lines in nearby high-tension line structures were consistently very nearly aligned with each other and my location on the ground. For power line structures of varying designs, I found that signal strength seemed to rise consistently when positioning my mobile radio unit at certain angles of incidence from the power lines. Certain structures seem to propagate RF better at certain angles, while other structures seemed to cause a spike in signal power at other angles, or when their power lines were aligned with my mobile antenna. All of these power lines did this more or less consistently, depending upon their common design.

Upon seeing this, I am led to believe that these power lines have in some way become "friendly" to certain signal propogation.

Pseudo-Yagi Redirectors? Parasite Elements?

While I am open to debate as to whether the RF propagation I have witnessed can definitively be attributed to these friendly power lines, I have tried to do some thinking beyond the open debate to assuming the RF rise is indeed attributed to be power lines.

Hypothesizing beyond this argument, I am prone to asking, "How are these friendly power lines helping me with my signal propagation?"

The first idea that comes to mind is that these power lines are serving as reflectors of signals coming from specific directions. By extension, and in placing this kind of signal directionality into words that many amateur radio antenna buffs understand, I propose the idea that signals are being either bounced or redirected off the multiple power lines toward my mobile antenna in a fashion rather similar to that seen with Yagi antennas.

Again, in all fairness to those folks who like to argue: No, technically the system I am describing is not a true Yagi - a single-system antenna composed of an intentionally spaced series of dipole-like elements designed to hike up RF gain from certain directions. However, for the sake of drawing a hopeful corollary, I am prone to liking this "massive Yagi" idea even more every time I think about it.

The idea here is to look upon the special positioning of the power lines as the "parasitic" elements of a Yagi antenna which direct RF for several hundred yards to the "driven" element (my mobile antenna) of this massive antenna system.

And Yes, It's Directional

After placing my mobile unit in the "sweet spot" created by the power lines, I confirm the characteristic directionality supported by Yagi antenna systems. The contacts I have made more or less do seem to run in a line at right angles to which the power lines course across the countryside. Also these contacts are also generally farther than I would normally be able communicate with the line-of-sight gear (10 meter transceiver) I am using, thus lending to the idea of a "driven" signal propagated by Yagi antennas.

Too bad I can't mount those massive lines on a rotor and turn them to selected directions!

Random thought: Perhaps I am using the largest known "pseudo-Yagi element" system in the world! For the sake of humility, I will pass this off and not lay claim to any world records.

Any Comments?

While I haven't attempted to take measurements using sophisticated equipment or analysis with computer modeling, I like the idea of attributing the rise in RF reception to the "massive Yagi" hypothesis I have described above.

However, in all fairness I'm open to discussion and other suggestions which you may have which would explain the rise in RF propagation I have witnessed. Please feel free to provide comments in the comment box provided on this page.

In the meantime.... 73!

- John

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ABOUT THE AUTHOR: John Melendez is a freelance technical writer reporting on high tech, the environment, sustainability, alternative energies and "green" issues. John Melendez is a writer for hire. To email him, go to http://www.emailmeform.com/fid.php?formid=19595

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