Dr. Emmett Brown's Random Wire Antenna

In early spring 2024 I had planned to spend some time reacquainting myself to constructing and testing QRO and QRP Random Wire Antennas for use with my Yaesu FT-891, Yaesu FT-817 and YouKits HB-1B. Throughout my ham radio experience, I've  piddled around with random wire antennas over the years but never really had much success with them.  Mostly because I'd never committed the time to properly construct a random wire antenna.

I certainly don't NEED anymore antennas. I have plenty. But I have a saying about antenna. They are like underwear. You can NEVER have too many. 

My main purpose for these Random Wire Antennas is to provide a smaller footprint. Since the Pandemic shutdown the amount of people using the Parks On The Air (POTA) sites I use has not dropped off but increased.  So in order to be safe and not intrude or disrupt other park users of enjoying the outdoors; a smaller footprint has become a necessity. 

First up was the QRO Speaker Wire Random Wire with 9:1 Unun to use with my FT-891. I had cut a 42' length for the radiator and a 23' length for the counterpoise during the spring of 2021. I threw the wire up 40 feet into a tree, connected the counterpoise and 25' of coax, connected all to my MFJ -971 Portable Tuner and couldn't get an SWR reading below 3.1:1 on any bands from 40 - 10 meters. Now committed to make this a better antenna I spent roughly an hour trimming the radiator and counterpoise to the point where I got SWR readings of 1.5:1 and below on 40 - 10 meters with a 28' 8" radiator, 17' 6" with 20' of coax into a 9:1 unun all through my MFJ-971 Portable Tuner.  Mission Accomplished!

             

With the QRO Speaker Wire Random Wire complete, time to move on to a QRP 26 AWG NO UNUN Random Wire for my You Kits HB-1B. Using the QRO Speaker Wire Random Wire length as a reference, I measured out 30' of wire for the radiator and a 17' length for counterpoise to use with a ATU-10 QRP Autotuner.  I found the sweet spot for the HB-1B / ATU-10 Tuner setup of a 34' 9" radiator, (2) 17' 2" counterpoises and 20' coax without an unun and no biting from common mode current. SWR with ATU-10 Autotuner for the 5 band HB-1B is 1.25:1 or less on 40,30,20,17 and 15 meters.  Two Down, One to Go!

   

I thought this final Random Wire for my FT-817 with the z817 Autotuner was going to be easy peasy to construct the next  .  WRONG!  I've now learned that each one of these radios have their own personalities with different tuners,wire material and rigs.

I quickly determined that using the same dimensions from the wire for the HB-1B for the FT-817/z817 just did not work out as expected. SWR on 40 meters with those dimensions was 1.15:1 but on 30,20,17,15,12 and 10 meters, readings were varied below 2.5:1.  Acceptable,  but I felt it could be better.  After trimming, raising the wire, measuring with Nano NVA, saving readings and looking over them; I found this wires sweet spot with a radiator of 31' 2", a counterpoise of 17' 6" with  20' of coax and NO UNUN.  SWR readings were 1.45:1 and below on 40 - 10 meters.  Finding the best setup for the FT-817 / z817 combo was a lot more tedious than I expected.

 

My Random Wire Antenna setups have given me options of a small footprint by throwing a line 30 feet into a tree and raising the wire vertical.

    

Or, raising the Random Wire vertical up with my 11 meter  SOTABEAMS Travel Mast.

    

 

The last six weeks I've used my FT-817 / z817 with the Random Wire more than my other rigs. 20 - 10 meters has been opening early in the mornings 1400 UTC at my POTA sites and I've been able to work some DX into Europe from Kentucky. USA.

Quite frankly, I've been amazed how my Dr. Emmett Brown's Random Wire Antenna has performed; especially with a QRP setup.  Below is a QSO map of my Morse Code / SSB POTA activations for a period from 11/15 - 11/19/2024

I have certainly have come to appreciate the versatility of a Random Wire Antenna in spite of it being a compromised antenna.  The time spent constructing all three for each different radio and tuner was time well spent and a valuable learning experience. 

And why do I call the antenna, "Dr. Emmett Brown's Random Wire Antenna?"  I was at a POTA site constructing the random wire. I had a spool of wire out, wire cutters, 11 meter mast, 15', 20' and 25' of coax, my Nano NVA, and my Panasonic Toughpad, all laid out on a piece of plastic on the ground . Several people came by asking what I was doing and I felt like Dr. Emmett Brown at the Town Square the night he was going to send Marty "Back To The Future". I wanted to tell my passerbyers I was conducting a weather experiment.  But I opted to stop and explain; I was constructing an Amateur Radio antenna. 

I now let my imagination run wild as Doc Brown, when I'm raising my Random Wire to send HF waves into the future.

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