[TowerTalk] 80 Meter beam

[Steve London]

I have a 2-element 80 meter wire beam, with inverted-vee elements. The 
boom length is 34 feet. The first thing to be aware of is the very 
narrow bandwidth. About 60 kHz between 2:1 SWR points, and the SWR 
shoots up rapidly beyond those points. This means you will only be able 
to cover a small portion of the useful 3600-3850 phone band without 
having to retune your matching network.

Consider the 2-element parasitic array, using a director, described in 
the ON4UN book, "Other Arrays" chapter. This design gives you 
directional reversibility, which has proven to be very useful. I have 
mine cut for the CW band, with the director tuned for resonance around 
3600. This means that on the phone band, the director becomes a 
reflector. Of course, the feedpoint impedance is a little screwy in the 
phone band, but that is taken care of with the feedpoint matching network.

If you are using open wire feeders, consider running 1/2 wavelength, 
open wire feeders from each element to ground level. Some ideas on doing 
this can be garnered from the K6NA design, in the ARRL Antenna 
Compendium, Volume 5.

73,
Steve, N2IC