Antenna Building in the Mojave

Winter Field Day 2023 was my first radio “communications exercise” (don’t call it a contest) experience. I viewed it as an opportunity to assemble a portable QRP (low power) kit powered by batteries/solar and see if I could make any contacts. My antenna selection consisted of several mono-band Dipoles and End-Fed Half Waves. I spent much of the 24 hour operating window raising and lowering the antenna mast to swap out radiating elements while chasing contacts.

As we approach Winter Field Day 2024 at the end of January, I wanted to take some time to streamline my antenna arsenal and decided to focus on building an Linked End-Fed Half Wave that would cover all of the bands I expect to work during the event (and a few additional bands that can’t be used during Winter Field Day).

I packed up the car with my radio, mast, and antenna building tools and headed to my favorite testing spot in the Mojave.

The antenna started with a Chameleon LEFS 4010 Matching Transformer (49:1) as a known-good design that is interesting as it also has connections (and apparently a separate circuit) to allow the same feed point to be used in a dipole configuration. My goal on this day was to cut and assemble the EFHW radiating elements and get the antenna on the air.

Through much trial and error, the elements were cut, attached to the feed point, tested with the Rig Expert Stick analyzer, soldered together, and sent back up the mast for more testing.

After several hours of construction and testing, I ended up with an excellent antenna that can be made resonant on 10, 15, 17, 20, 30, and 40 meters without a tuner. While I will still have to lower the mast when I’m changing bands, the process will be much easier than swapping out radiating elements on the dipoles and will instead involve the simple disconnection of a barrel connector. The SWR for all bands is 1.28:1 and below, and some bands are very close to a perfect 1:1 match.

I expect the antenna to perform well for both CW and SSB contacts. In the meantime I’ve still got more CW practicing to do before I feel comfortable with the Winter Field Day contact exchanges!