[SECC] Antenna improvements (Was: NAQP)

[Bill Coleman]

On Aug 23, 2007, at 10:21 AM, K9AY wrote:

> I have not had experience with multiband verticals, but in the past  
> I have
> used elevated ground planes for 15, 20, 30 and 40 meters -- all of  
> which
> performed much better than their ground-mounted equivalents.

There was a key study sited by W8JI on TowerTalk several years ago.  
The AMBC guys had actually investigated using a few elevated radials  
rather than a standard ground-mounted radial system. BC stations  
specify 120 1/2 wave radials, which is way better than most amateur  
installations.

The bottom line on the study was that the ground-mounted system gave  
higher field-strength readings than the elevated system. So, they  
stuck with the ground-mounted system.

So, I think it depends on what you are comparing. If you can only put  
down a few radials, then elevating them makes sense. Putting up a lot  
of elevated radials is harder, since you need to support them all.  
(Although W4WA does have that huge spiderweb of 60 1/4 wave radials  
for 160m at 10 feet...)

The other issue is height. Above 1/4 wave high, a few elevated  
radials work great. Below 1/8 wave, its not so clear.

Consider:

Case A: 4 radials below 1/16 wave versus 4 on the ground.

Case B: 4 radials below 1/16 wave versus 30 on the ground.

Case C: 4 radials above 1/16 wave versus 60 on the ground.

I'd say case A is a definite win for elevated radials, but case B  
favors the ground-mounted system. Case C isn't so clear. The exact  
height of the radials would be the determining factor.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901