Good info Steve, I wonder a couple of things though. First, why 8 degrees for the takeoff angle? That puts it low enough that you're into the ground effect suck-out zone fairly heavily. I'd have though something like 25 degrees would be a more representative angle for typical communications use.
Also, what is the effect on the Force 12 antenna if it is between 1 foot and 28 feet off the ground? What if it is 15 feet off the ground (i.e. on my garage roof)? - Keith N1AS - - K2 5411.ssb.100 - -----Original Message----- From: Stephen W. Kercel The discussion of verticals has inspired me to do a bit of EZNEC modeling. I plotted the azimuthal pattern at an 8 degree takeoff angle for several different 80 meter configurations. In all 3 cases, I've assumed average ground. The first case is the classical full size vertical, with a quarter wave monopole element and 128 quarter wave radials. *snip* the pattern is an omni pattern with a signal strength at 8 degrees takeoff angle of -2.72 dBi. The second case is the Force 12 vertical dipole, with no radials. ... bottom of the antenna elevated 28 feet above the ground. ... The signal at 8 degrees takeoff angle is an omni pattern at -3.09 dBi. ... an undetectable quarter dB worse than the ideal full size quarter wave configuration. How important is the mounting height? It matters. For the same configuration except with the bottom 1 foot above the ground, the signal strength at 8 degrees takeoff angle is -5.8 dBi. This is a quite noticeable >3db degradation from the full featured quarter wave configuration. _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
