Topband: How to orient the receive antenna?

[Tom Rauch]

> 40 degree Beverage...".  How many Beverages does it take?  How do you
> decide which way to aim them?

Beverages are fairly wide pattern antennas, so one every 45 
degrees is generally enough. For a long time in the early 70's, I 
lived with only two reversible Beverages. 

> In John's book, he makes it abundantly clear that DX is really not to be
> expected along the great circle directions. 

There is no way to predict the arrival path of a distant signal, 
except for saying "it's sorta that way". For example, an LA3 has 
(and other northern Europeans) regularly been coming in here due 
east or slightly south of east. That's more than 45 degrees off the 
normal path, no where near gray line, and consistent night after 
night in the mid-summer.

The longer the path, and/or the closer to crossing near the 
magnetic poles, the more often they skew. It's common here to 
hear JA's on two paths, one west or south west and the normal 
NW path.  

> In my acreage-limited existence (less than 1/20th acre), I shall
> inevitably be utilising pennants, ewes, K9AY loops or other such
> compromise antenna.  They have wide forward lobes, so there seems not much
> to worry about there.  But the nulls in the reverse direction - ah, that
> must be what is critical!

That is what is critical. Gain has nothing to do with receiving ability 
(as long as it doesn't put the signal into internal system noise). The 
ratio of null area and depth to main response area (in the direction 
of the desired signal) is what makes a receiving antenna work well.

> there find the need to make them rotatable?  It occurs to me that will be
> the only way for me to be confident that I can null out QRN, QRM or noise
> overall.  At least, until I determine that there is one (or perhaps two)
> desired directions.

You'll probably find, unless you have a local noise source, rotating 
any small antenna is unnecessary. Just aim it in the right general 
direction. It takes a physically large array, at least 200-300 feet of 
area, to produce even a modestly narrow pattern on 160 meters.  


73, Tom W8JI
w8ji@contesting.com



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