Topband: T Top Verticals and yagis

[Jim Brown]

On 2/27/2020 8:23 PM, donovanf at starpower.net wrote:
> Your conclusions based on your modelling are completely consistent
> with my practical experience and modelling.

My experience with building what I model or modeling what I've built has 
been that if I've built the model to accurately represent ALL of 
reality, the model correlates well with how the antenna works. This 
applies equally to matching networks and other circuitry.

In my professional life, I did pretty complex models for the large sound 
systems I designed, often including acoustic models of large public 
spaces where they would be installed. The sound system models were an 
order of magnitude more complex than most antenna systems, and the 
acoustic models an order of magnitude more complex than the sound system 
model. Again, results were as good (or as bad) as the data that I put 
into the model.

And in my third year of EE, '61-'62) my coop job was crunching numbers 
for Pete Johnson for his designs of multi-tower AM broadcast arrays. 
Pete and Carl Smith (Cleveland Radio and Electronics Institute) wrote 
the FCC technical Rules for the AM band after WWII. Four of us sat 
around a conference room table with slide rules and math tables filling 
very wide paper spreadsheets with 25-30 columns of numbers, each column 
being the result of one step in the calc. The calc was repeated for 
every 5 degrees of azimuth and 5 degrees of elevation. It could take 
days to finish a pattern. Pete would study the results, change a 
variable or two (magnitude and phase of current in elements, move the 
towers around, etc) and we'd do it all again. In 2020, the same model 
could be computed in the laptop on most of our desks in a few minutes.

73, Jim K9YC