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NVIS antenna height notes from w8ji

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(@kx3dx)
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The link below is a good short read.  Basically it documents that a horizontal half wave dipole at 1/4 wavelength above the ground (65 feet on 75M and 33 feet on 40m) is an optimum height for NVIS operation.  Reducing the height to 1/8 wavelength above ground (33 feet on 75M and 16 feet on 40m) retains the exact same NVIS pattern but the gain lowers a DB or two.  Further lowering the antenna retains the NVIS pattern but the gain drops off a bunch.  I have a 80m dipole at 40 feet height - because that is the height of my trees - so I guess it's a NVIS antenna but not by choice.  I'm not going to lower it to put out a poorer signal with the same NVIS pattern.  Food for thought.

https://www.w8ji.com/nvis_n_v_i_s_antenna.htm

73, Dave Larkspur


   
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