QRP, Portable End Fed Antenna


End Fed Antennas Used

Here's where the interesting part begins. First, the list of what I used:
1. LNR Precision EF-20 End Fed Antenna
2. EARC 20M End Fed Antenna - Built from their specifications
3. EndFedAntennas.com 20M End Fed Antenna
4. Homebrew 20M End Fed Antenna based on EARC and LNR Precision designs

I would also like to note that a lot of information was gathered through research based on books such as Transmission Line Transformers by Jerry Sevick, W2FMI, and from "The G Whip Man", Frank in England, GW3DZJ.

Assembling and Tuning

After ordering antennas, parts, boxes, wire, etc... I began the task of creating the end fed antennas, or just assembling the pieces shipped to me per instructions packaged with the product. However, the end fed antenna from EndFedAntennas.com came complete as a unit. It didn't allow for tuning, which, to start, was unusual since the others refer to needing tuning. More on that a little later. I pre-tuned all of the antennas out beside my little shop prior to going into the woods so that I could quickly get each up in the air and get to transmitting. For tuning, the MFJ-269 was used.

Per LNR instructions, I assembled the necessary parts and was ready to get it up in a tree in a relatively short amount of time. We'll say about 10 minutes or so while following the brief instruction paper sent with the antenna. LNR recommends tuning both the wire antenna and the short stub, if necessary. It takes a little time to get it right, but it gets good bandwidth across the 20M band.

For the EARC and homebrew end fed antennas, it took a little longer since I was building from spec with EARC and then building a test rig for the homebrew. Maybe an hour for each. This doesn't include tuning time. For the EARC end fed antenna, they recommend cutting the coax at about 9.5" long and enclosing it in the box and tuning the wire side of the antenna, so I did as they suggested. There were 22 turns around the toroid with the enamel coated winding wire. I used a 34 foot piece of THHN to start the tuning process. A little long, but it would allow me the necessary length the ensure I could start tuning well below the 20M band and bring up the frequency with each trim of the THHN. This yielded about the same results as the LNR end fed antenna.

For my homebrew end fed antenna, I left everything open within the box so that I could tune everything independently. I ended up with 25 turns around the toroid, 9" of RG-174 and 33'6" of THHN antenna wire. Tuning like this takes much more time, but I was rewarded with a better SWR sweep across the 20M band, along with better impedance matching.

Now, the EndFedAntennas.com order, as I noted above, was a complete unit, ready to go up in the air. There was a loop soldered at the end of the wire antenna side to allow for tieing it off to rope or whatever you may use to pull it up into a tree or other object to get it off the ground. So, assembly time - none, and as you'll see, tuning time, none. Once I got the antenna in the air, I was pretty damn shocked to see the bandwidth over the entire 20M band. It has a usable 1.2 MHz bandwidth, and the entire 20M band was below 1.5:1 SWR with almost a perfect Impedance match with very little Reactance. In other words, everything you would feed it from the transmitter was being emitted through the antenna! I tested this particular antenna as a sloper at a 45 degree angle, as a flat-top antenna, and as a vertical, with the vertical yielding results that were absolutely excellent! Since this antenna was assembled with a hardened potting epoxy, I was unable to match their network without destroying the antenna network itself. A well assembled, tiny little antenna. This particular antenna network can almost go in your pocket.

Parts for EARC and Homebrew

If you're going to go through the motion of building your own end fed antenna, then you need parts. You'll need a box or container of some sort to enclose the matching network, SO-239 connector (I use, prefer and recommend Amphenol), Toroids (I used T80-2), enamel coated copper winding wire at 24 AWG or there about, some RG-174, and finally, some antenna wire. I used 14 AWG THHN since it's very easy to get at any hardware store. Since I already had rope and RG-213 (radio to antenna connection) here at the house, I was good to go on both of those. I will link to the EARC document on the Information page so that you too may be able to see the internals of these builds.

Ready To Go

With each end fed antenna tuned to the Nth degree, I was now ready to grab my gear and head out to the woods. So let's go see how I got these things in the air!