Topband: New 160M high performance receiving antenna at W3LPL

[Tom W8JI]

Hi Frank,

>
> I used a pair of 270 foot spaced broadside 580 foot Beverages for several 
> years but the improvement was insignificant compared to a single 580 foot 
> Beverage.  I replaced them with single 900 foot Beverages which perform 
> slightly better than the 580 foot Beverages.  I have inadequate space for 
> more widely spaced broadside Beverages.
>>>


We sometimes see claims broadside spacings less than 1/2 wave result in 
useful S/N or directivity improvements. They do not.  Gain goes up 3 dB 
(because the individual elements are so lossy), but pattern does not change 
any significant amount. When pattern does not remove unwanted signal areas 
significantly more, S/N  cannot change significantly. We can't improve 
things by nulling unwanted stuff out of an area that already has very little 
response.

My results with Beverages are similar to your results. The problem with 1/2 
wave spacing is it tries to force a null where the individual elements 
already have a null. In order to improve weak signal performance, we have to 
force new nulls where significant response exists with the basic element. We 
can't make things significantly better by just adding a new null inside an 
existing null, because there is already nothing of consequence there to get 
rid of.

Since a 1 wave long Beverage has deep side nulls, adding a second antenna at 
a spacing that forces new nulls in the area of existing nulls is a waste of 
materials.

> You've surely built and evaluated more BSEF and 8-circle receiving arrays 
> than any of the rest of us.  I'm very new to them and after just a few 
> days of evaluation I'm delighted with the results of my new BSEF receiving 
> array consisting of four 25 foot W8JI umbrella verticals spaced 300 feet x 
> 130 feet.  I still have my 900 foot Beverages, but so far the performance 
> of my new BSEF receiving array is consistently superior.
>
> If you were to install a new BSEF receiving array using four W8JI 
> inductive/resistive loaded 25 foot umbrella verticals (not an 8-circle 
> array) what spacings and fixed phasing would you use based on your 
> experience and evaluations?
>

I can't really give a specific answer because the optimum phase depends on 
the element combination and what people are after. What is best at one place 
is probably not best somewhere else, and it is the combination that matters. 
The only certainty is 1/2 wave broadside and 180-s phase is almost never 
optimum for anything, including transmitting.

For receiving, I would plan the phasing or spacing of directive cells so 
each complementary cell forced the largest possible area null where other 
cells had significant undesired response.

73 Tom