The Ubiquitous Random Wire Antenna

In the history of Amateur Radio...is there an antenna that is more misunderstood and incorrectly characterized than the RANDOM WIRE?

To best describe the random wire, you need to understand WHAT it is.  Simply, it is a wire of random length.  It could be 10 feet.  It could be 50 feet.  It could be 300 feet.  It is whatever you install for your application.  This should not be confused with the LONG WIRE.  The LONG WIRE is a two-wavelength or more antenna...cut precisely to work on a certain band/bands.  Some even describe the long wire as an end-fed wire.  Whatever you call it, a random wire is just that...RANDOM.

To make a random wire, you start with...wire.  Simple enough.  Next you need a path.  How are you going to install it?  Or get it out of the house, etc?  RF concerns?  Remember...every inch becomes a radiating antenna.  My random follows the same path as my satellite antenna's feed, the RG8/U for the Hustler, a Cat 5E run, the grounded twin-spans of RG58, etc.  It comes out of my shack/office, under the stairs, up into the rafetrs of the basement, out through a nice holesaw-cut hole into the garage, makes a 90 degree turn to the piped porthole that exits the garage, 90s up for 2 feet, 90s right then for another 35 feet to the Silver Maple tree in my backyard.  That's the beauty of the random wire...it DOESN'T NEED to be straight.











Recently, I took down the OCF Zepp I had been using for too many years.  It just wasn't doing as well as it should have been, I felt.  In its place, a Hustler 4BTV was erected...but I still needed something for everything ELSE that wasn't 40/20/15/10 meters.  The idea came for the random wire, when in 2009 during my Church's Radio Club's Field Day, we installed a 150+ foot random wire that made a lazy inverted L.  We also used a ground rod for the counterpoise.

The use of a ground rod/counterpoise is what will make or break the random wire.  Many hams incorrectly get the idea that if they toss a wire out of their window, it will earn them DXCC.  Perhaps on 10 meters during the Solar Peak of the late 80's/early 90's this would have worked (I did it as a Novice), but realistically, it IS NOT the correct, efficient, or recommended way of using a random wire.

In order to have a random wire be as efficient as possible, there are three things you need to keep in mind:

1) Avoid lengths that are near a half-wavelength of ANY band you want to work.  You will have more problems than it's worth.  

Ideal "random" lengths are: 29, 35, 41.5, 48, 71, 84, 107, 119, 148, 203, 347, 407, 423 feet.  (Mine is about 71-75 feet.)  Typically, 70-80 feet is good, since you can use it on ALL bands...at 160 meters, a quarter wave is about 65 feet...at 75 feet, this antenna appears to "randomly" be about .27 wavelength.   This would work reasonably well on 160.

2) YOU NEED A GROUND, COUNTERPOISE, or BOTH.  It makes up the "OTHER HALF" of the antenna.  In my installation, I had my Zepp's ladder line attached to twin spans of RG-58 to make it easier to enter the shack.  The shields were connected together and grounded.  When I took down the Zepp, I left the feeds in place...in case I ever wanted to use it again.  Since there was a path to ground that was established previously, I didn't need to worry much about this step.  For new installs, it is 100% essential!

3) YOU NEED A TUNER.  In case you missed it...YOU NEED A TUNER.  Random wire antennas have SWRs that approach infinite in places...but 5:1, 10:1 or more is also possible.  NO radio built within the last 20 years will tolerate that type of mismatch for very long.  When selecting a tuner, it needs to have a post, or similar, to attach the single wire feed of the wire.  A good performer in this case is the MFJ 941E Versa Tuner II, or the MFJ 16010 random wire tuner.  

With all 3 of these principles adhered to, you should have a fairly decent antenna for what has been considered a compromise antenna.

During the 2011 CQ WW RTTY contest, I was using the Hustler primarily.  It worked extraordinarily well on 40, 15, and 10.  On 20, its SWR was 2:1...still OK.  But, I wanted to work the "locals" (stations between 25-500 miles away)...so I had to QSY to 80 meters.  On 80, my random loaded to 1:1, and even with QRP power, I could work everyone I heard...even with one call.  

Also, there are times that the random can hear better than the Hustler on certain paths.  It's nice when I'm operating the 3905 Century Club Net to switch to the random to compare.  Just last night,  the Hustler just wasn't doing it for one station in Iowa.  But, on the random, he was 5x5.  Impressive.

The true test will be this winter when 160 once again becomes a popular hangout.  I am already "chomping at the bit" for the 3905 CCN 160 Meter Net to start...if only to try out the random wire.