Portable QRP End Fed Antenna Information
In the beginning...
I believe we're all pretty aware that it wasn't all that long ago when portable meant mobile, or clipping a small HT to your belt and working 2M or 70CM. Not much in the way of DX up there in the VHF and UHF frequencies when portable. However, within the past several years, manufacturers have built smaller rigs. Rigs capable of being thrown in a backpack, for instance, and toted deep into the woods and used as a QRP station. Unfortunately, a decent antenna usually meant dragging ladder line, long wire and a tuner with you. These days, there seems to be a few folks who have created half-wave, end fed antennas that work reliably and allow us outdoor types to carry less and be more efficient in our contact efforts at 5, 10, or even 100 watts. Digital modes have been introduced that create a world of new ways to make contacts and log them quickly within the software packages. PSK, for instance, doesn't need legal limit, and is as reliable as any other mode available. With about 40 watts, you can reliably work Europe, the Caribbean, South America, etc... on 20M effortlessly.
Simply put, QRP means using the lowest power possible to achieve the widest effective range of transmitting. Enthusiasts of QRP are building transmitter and receiver kits within the confines of Altoids tins. I personally have two Altoids tins, one very small tin for receive only, and another that was for both transmit and receive of digital modes for my ICOM-706MkIIG before I sold the ICOM. I use the receive only tin for my Kenwood TS-430S home base station. This way, I can still monitor PSK, Slow Scan, RTTY, and other digital modes while just hanging out and working on other projects. With QRP, the operator generally runs very, very low power, but up to about 100 watts. Most QRP contacts I have made, as the operator I run about 10 watts, and other operators seem to run about 5 to 10 watts. Yaesu has created a radio specific to those folks within the QRP environment - the Yaesu FT-817, capable of only 5 watts output power.
End Fed Antennas
End Fed Antennas are one half wavelength long, with a network on one end feeding the entire length of antenna wire. I have worked with 10, 20, 40 and 80 meter end fed antennas at this point. I was usually running 50 to 75 watts power into the antennas with excellent results. So much so, in fact, that I now use a 20M End Fed Antenna as my base station antenna here at the house. The matching network is about 20+ feet up in a pecan tree, and the other end is about 8 feet off the ground, sloped towards the north. You can vary the direction you want to broadcast by moving the sloped end around towards which ever direction most suits your needs. For instance, someone in Canada may want the lowest end pointed south, so that the radiation angle is aimed towards the US. Or aim the end east, if in Nova Scotia, to work Europe. If you can get the antenna high enough to use as a vertical, then you will be amazed with the results. The antenna can also be configured as an inverted L or used as a flat-top antenna. The easiest hanging configuration is probably going to be as a sloper for many of us, but give vertical a shot and see what you think.
The ends of these antennas create a tremendous amount of voltage. Depending on your input power, you could end up with well over 1000 volts at the end of the antenna. Please, please, please use caution when planning your hanging configuration for these antennas. The last thing you want to do is have someone grab the end of the wire when you key up to transmit. Hospitals become an expensive hobby, and we all know the one we have with amateur radio is expensive enough. Now on to the antenna tests!
Follow the link below to my setup, tests and results.