[MAMS] How weather affects Tropo conditions

[Dr. Gerald N. Johnson]

The program ele.bas based on DL6WU data from G3SEK or now GM3SEK's 
website works for me. My last 432 yagis give more gain on the CSVHF 
antenna range than computed. Its been around a long time but DL6WU did 
it right. It is a dos program but I'm running it in XP using 
gwbasicwin.exe. If you can't get those from GM3SEK, I can put the on my 
server for a bit. I can't help for mac.

The DL6WU technique is to make a two element yagi, reflector and driven 
element with an adjustable gamma match for the driven element. The mount 
the element length without boom insulated (like a foam boom) fairly 
close to the driven element, then tune the gamma for a perfect feed 
match. Replace the insulated element with the desired boom and element 
mount and trim the through the boom element until it give the same 
impedance match without changing the gamma. Using the two element yagi 
as a measuring tool for the reactance of the director being tested. And 
his antenna designs are based purely on a smooth distribution of changes 
in director reactance going from the driven element to the front 
director. They are not randomly compute optimized and so are most 
tolerant of length errors compared to the tightly optimized yagi where 
the optimization may have gained a dB of gain at the cost of higher side 
lobe amplitude.

73, Jerry, K0CQ

On 1/9/2014 8:57 AM, Zack Widup wrote:
> That would be very interesting! Let me know if you find it.
>
> There's something I've been looking for, too. I recently saw an article in
> a proceedings or compendium that gave a way to calculate element length
> correction factors for elements going through metal booms. I have seen
> other articles on this but I only want the article that has been in a
> proceedings or compendium in the last year or two. Maybe one of the recent
> ARRL antenna compendiums? I just can't remember where I saw it.
>
> 73, Zack W9SZ
>
>
>