Topband: Phased "Flags"

[Larry Molitor]

At 07:37 PM 12/28/00 -0500, Tom Rauch wrote:

>Assuming your noise is mostly sky-wave, you give up S/N
>advantage pretty quick as spacing gets to 1/2 wl (and especially
>anything narrower). If the noise is groundwave, very far from the
>antenna (a few thousand feet or more), and directly off the sides
>1/2 wl spacing may be useful.

*The offending noise is all ground-wave. Locally generated, ranging from a 
little over a wavelength to a couple miles away. Seems like most folks 
assume the offending signals are sky-wave. But remember, if you have to 
resort to a small RX antenna like this, chances are your QTH is buried in 
urban noise, all locally generated. I can only dream of a QTH where 
sky-wave is the problem!

>I use 330 ft or more on most broadside arrays. With sky-wave
>noise, there is a big advantage that is clearly heard when I
>compare two antennas at 1/2 wl and two at 330 ft spacing. Maybe
>you should use the wide spacing and get a phase shift system that
>lets you steer the main lobe.

With the 315 foot spacing, there is no discernable advantage over a single 
flag. I can do A-B switching and the differences average out. There is a 
slight advantage when looking at AM stations in the top end of the AM band, 
hence my thought that narrower spacing might be better in this application.

A good phase shifter is planned (NOT a MFJ!) for a future project. It would 
seem that is indeed the best answer. But that's several weeks in the 
future, at best.

73,

Larry - W7IUV


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