Bob Archer was part of the aerospace crowd back in the late 1950’s and a creative engineer when it came to RF. Throughout his life he published numerous articles and papers on antenna design. Some of his designs broke traditional logic and have stood the test of time. One of these is his zero-drag internal aircraft navigation antenna – widely known as the “Archer Antenna”.
The Archer VOR antenna is designed to install horizontally inside the fiberglas wingtip. For this reason, it’s is frequently used today.
I decided I had spare time on my hands and had a good enough reason to want an “Archer VOR antenna”.
As Paul Dye once said, “I am not an RF engineer – I just listen to guys that are, and Mr. Archer is“.
The documentation Bob Archer published regarding his zero drag internal antenna has been poured over by many RF people and they eventually documented their work.
There is now a highly detailed fabrication diagram online at AeroElectric.com to produce a DYI VOR antenna. (Here is a direct link to the PDF.)
I took the time (and my digital calipers) to build according to these newer plans.
Total build time was about 2 hours. That broke down into about 90 minutes of measuring and 30 minutes of cutting and assembly. The process was very easy.
Using just a handheld radio, standing in my front yard, and without the benefit of the aircraft ground plane, I picked up the localizer which is approx 4 miles away. This wasn’t a definitive test. I still needed to try a similar in-air test.
Addendum: The in-air test was performed with just an old handheld radio and no groundplane for the antenna. Reception of VORs started being usable at 40-50nm. Once permanently installed with the correct groundplane, the 50nm goal should be easy.
Installation Note: Bob Archer understood a wingtip installation would involve the aircraft’s position lighting system. He made explicit reference to this. Any lighting system wires must be routed along the forward angled element of the antenna to avoid cutting off the RF radiation which has a similar effect as grounding the primary element of the antenna and dramatically reducing its effectiveness.