[NLRS] Adding a 6M Beam

[Dr. Gerald N. Johnson, electrical engineer]

Purists grumble about the effects of a 432 stack between stacked 144 MHz
beams. But we should groan about the idea of sticking a 6m beam between
two 144 stacked yagis. The 6m elements are going to be strongly coupled
to the 2m RF and because they are close to resonant at 3/2 wavelength
the 6m elements will not radiate energy along the boom but at about 45
degrees from the boom. At the last the combination will increase side
lobes on the 2m side. At the worst the 2m beams will loose quite a bit
of gain from proximity to the 6m beam between them.

A better check would be to model the stacked 13B2 with and without the
6m beam using something like EZNEC. Avoid YO type programs, they don't
compute proper element couplings when the elements aren't close to 1/2
wave resonance. They will produce numbers but not correct numbers.

The "beam width" of the plain dipole is very broad, mostly notches off
the ends. A second one at right angles will completely fill in the
pattern. If on the same mast and fed 90 degrees apart its a turnstile
with an fairly circular pattern. Else switching from one to the other
makes for rapid 90 degree direction switching.

73, Jerry, K0CQ

-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.