from Survival Blog:
I consider the ability to communicate in a TEOTWAWKI scenario, and being able to obtain information outside the immediate area, critical. HF communication best fills this need. I had the radios but needed an antenna that would work on most amateur bands and others if needed. Having recently relocated to a more free state, I had all the real estate to put up whatever antenna I wanted. I wanted an antenna that fit into the space of a dipole, is relatively invisible, easy to build, and can be coax fed. The need to bury the cable ruled out a ladder line and tuner fed, all band antenna. A remote tuner was also out, since it added a potential point of failure.
My search of the Internet led me to the OCF (Off Center Fed) antenna design. An OCF antenna is similar to a dipole, except that it is not fed at the center but at a point offset from the center. This offset gives the antenna the multi band capability. This article as well as this one best explain how and why this type of antenna works on multiple bands. Unlike Terminated Folded Dipoles and End Fed Inverted V antennas, an OCF antenna works on multiple bands but not on all frequencies. The benefit of this is that the OCF antenna is much more efficient in getting the signal in the air, rather than heating the terminating resistors, like on the other two antenna types. A properly tuned OCF also does not require the use of a tuner.
This article describes how I built a multiband OCF antenna, including the actual dimensions, measurements, and some performance information. While primarily designed for the 80/40/20 meter bands, this antenna also works on 17/12/6 meters. The article is geared towards people new to antenna building, so it may seem redundant or lengthy to old timers. There are several vendors that sell ready-made OCF antennas, but I wanted to build my own, so I would know how the antenna is put together and how to repair the antenna in a SHTF scenario, in case it gets damaged or wiped out.
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