Some more results modeling HF ground planes with EZNEC.
I took my existing 40 meter ground plane with a 33 foot vertical
element and elevated radials at six feet high, which had a resonant
impedance of about 30 ohms, and reduced the radials down to a mere
five feet. Now the antenna is resonant in the 60 meter band with an
impedance of about 97 ohms.
Presto - a two band antenna with SWR of less than 2:1 and no traps or
switching and just one simple vertical element. 2:1 is well within the
capability of my rig and at such low frequencies, the loss from SWR is
negligible. Azimuth and elevation patterns are essentially the same as
with full length radials.
In other words, just add four five foot radials and get a second band.
This is too easy! :-)
Looks OK on the screen but will reality be as good? There might be a
gotcha in there somewhere. We'll see.
73, Bill W6WRT
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