Topband: 160 meter 1/4 vertical

Mike Waters mikewate at
Mon Jul 3 18:30:47 EDT 2017

Respectfully, there's a lot of misinformation here.

"Clearly, size matters." If you are saying that the taller a vertical then
the better the signal, then that is simply *not the case*. It is a very
well established fact that a 160m vertical taller than λ/4 has little --IF
ANY-- DX advantage. (Rather, the opposite is true.)

The free-space pattern of any antenna depends _on its dimensions_. They are
not all "crescent shaped".

And improper matching does LITTLE to affect the pattern of an antenna,
unless we are discussing phased arrays. The pattern of a vertical or dipole
by itself will not be affected by a mismatch.

Perhaps the 73 article you mentioned described some type of phased array,
and is correct. However, 73 was noted for some gross technical inaccuracies.

73, Mike

On Mon, Jul 3, 2017 at 5:09 PM, Charles Moizeau <w2sh at> wrote:

> The free-space pattern of current in a vertical (and also  horizontal)
> antenna is crescent shaped with its maximum at the midpoint, and a minimum
> at each end.  It shows nothing that could be termed an extraneous lobe.
> Any such lobes would seem to be the result of improper matching, or more
> likely, the fact that in the real world such an antenna is in an
> environment that is certainly not free space.
> The Franklin collinear antenna is usually shown either with in-line
> 1/4-wave inverted coaxial segments, or for wire antennas with quarter-wave
> decoupling stubs hanging down from the adjacent ends of the in-line
> half-wave radiating sections.  For the latter, the quarter-wave decoupling
> stubs can be reshaped so that they run parallel to the half-wave radiating
> sections, and this makes for a neater configuration.
> Years ago 73 Magazine had an article describing a 7/8 wavelength vertical
> mobile antenna for VHF (two meters).  The bottom section was 1/2 wave and
> presented a high input impedance, and I believe used a LC matching
> arrangement to the 50-Ohm coaxial feedline.  The top section was 3/8
> wavelength and decoupled from the bottom section with just a low-value
> capacitor.  I seem to recall that the overall dimensions were for a length
> that was 5/6 wavelength, but that is only five percent less than 7/8
> wavelength.  The article showed comparative field-strength readings that
> showed superior results for this antenna versus 1/4, 1/2and 5/8 wavelength
> antennas.  Clearly, size matters.

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