Topband: [bevantennas] Ground screen under beverage....

[donovanf at erols.com]

Many years ago I was involved -- peripherally -- with very large phased arrays 
of Beverage antennas installed over very poorly conducting soil (almost 
solid rock) in which ground rods were completely impractical and 
ineffective. The design of these arrays predated the availability of 
general purpose computer-based antenna modelling; however, the designers 
did develop custom method-of-moments software models of the array. 
Importantly their design also involved extensive measurements of 
individual Beverage antenna patterns and Beverage array patterns 
by use of sophisticated airborne sensors. 


Both ends of every Beverage in the array used fifty foot sloping wires over 
conductive ground mats. Each mat consisted of chicken wire fencing 
material about sixty feet long and ten feet wide. The mats extended about 
ten feet beyond the feed point and termination connections to the mats. 
The mats did NOT extend under the horizontal portion (the antenna portion) 
of each Beverage antenna. 


The entire array was installed in a secure fenced area with no possibility of 
human or wildlife intrusion. Among other things that allowed antenna 
height of only four feet which resulted in improved front to back ratio and 
reduced sidelobes especially at higher frequencies. 


The engineer who lead development, testing and evaluation of the array 
explained that the ground mats served two purposes: 


- substituted for ground rods that couldn't be used in mostly solid rock 


- almost completely suppressed signals received by the sloping ends of the 
Beverages by making them into efficient transmission lines with very low 
spurious signal leakage compared to a sloping wires over poorly conducting 
soil or vertical wires at each end of a Beverage. 


73 
Frank 
W3LPL 




----- Original Message -----

From: "Jim Brown" <jim at audiosystemsgroup.com> 
To: topband at contesting.com 
Sent: Friday, October 2, 2020 3:46:56 AM 
Subject: Re: Topband: [bevantennas] Ground screen under beverage.... 

On 10/1/2020 5:03 PM, Grant Saviers wrote: 
> Worse than "not the best" or "not a good idea" from prior experimentation. 

And a clear indicator that whoever proposed it failed to learn how 
Beverages work! It all goes back to Mr. Beverage's original patent more 
than a century ago. 

Beverages DEPEND on lossy earth beneath them, and DXpeditioners who have 
tried them over high conductivity ground near the sea quickly learned 
that they don't work. 

73, Jim K9YC 
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