Beaming Direction

Analysis of a fixed "boom" in the attic


One problem with attic antennas is the space available tends to allow for beam construction only along one axis.  If your house lines up with a favored direction, then that's very good.  If not, it can be bad.

Fortunately, my house attic "boom" is oriented ENE at about 60 degrees from north.  That places the center-line of the beam (going east) on Kenya.  And (going west), on ZL land.  In the plot below I have added center-line +/- 45 degree lines to show the typical coverage of a 90 degree beam-width pattern. 

Looking east, the antenna covers most of EU and all of Africa.  Unfortunately, this orientation also places Asia and South America almost exactly in the null of the typical beam pattern.  I had not fully appreciated this prior to adding a dipole along the boom which provides 10m service to the Asia/SA path.

The 40m antenna already has an omni-direction capability as part of the phased drive. And because of the success of the 10m dipole in the recent 10m ARRL contest, I am looking into ways to multi-band that element to provide some additional coverage on 12m and perhaps 15m. 

With attic antennas, the optimization never stops!



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