Hello, Don, Dave, et al, Don said "The only problem with that is the high voltage point on a fullwave loop is electrically opposite the feedpoint, not 1/4 wave away from the feedpoint."
Not so. Here's why... Define a quad, full wave loop, as a square -- geometrically equal lengths on all sides. Feed point (zero degree point) is placed on the center of one side. On a "closed" full wave loop (360 degrees long) there are always 2 current maximum points (loops) and 2 current minimum points (nodes). The same for the Voltage standing wave -- there are always 2 voltage maximum points (loops) and 2 voltage minimum points (nodes). Current and voltage maximas, on a standing wave antenna, are 90 degrees apart. On the defined "closed" full wave square loop, the current maxima (loops) are at the feed point (zero degree point) and 180 degrees around the loop or half way round the loop on the opposite side. Then, the voltage maximas are 90 degrees away from the feed point (or 90 degrees back toward the feedpoint from the 180 degree point) -- 1/2 way between the feed point and the 180 degree point, physically centered on the adjacent sides to the feedpoint side. Summary and benefit of this characteristic for a multi-band antenna -- Opening a full wave loop at a voltage maximum (current minimum) does not change the closed loop standing wave pattern for the fundamental frequency, but opening it forces a dipole type sinusoid current distribution on the 1/2 sub-harmonic. Works great for when you are trying to control the current distribution on both bands for a specific pattern generation. Hence, my original suggestion. TNX and Regards..Rick -- W5RH _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
