[600MRG] Trap verticals

[Rudy Severns]

Hi Ken,

 

First off I plead ignorance, I've never looked into or used trap antennas.
I've been fortunate to have the space to put up mono-banders.  I understand
the general principles behind trap antennas but that's not the same thing as
"knowing" how to design one.  If I wanted to solve your problem I wouldn't
spend much time calculating.  There have been some articles on calculating
traps over the years because there was no alternative except calculation
combined with experimental cut-and-try.  But now we have excellent modeling
programs.  

 

I assume you have an antenna modeling program?  If not, Google 4NEC2 and
download it for free.  It's a great program which will do 95% of what you
need for LF-MF antennas and it'll run any cheap machine, I use a $100
machine from Goodwill recycle!  I have much fancier software but that's only
for the last fine details involving buried wires and such.   I suggest you
start by modeling the antenna you're currently using/taking down.  That
gives you a known quantity from which you can explore other options.  

 

It is true, if you have not been modeling there is a learning curve which
will require you to invest time in learning how to make the software play.
That can be a frustrating time but I guarantee you if you struggle through
the early fog and get going with the modeling you will never go back.  You
will only wonder why you waited so long!  Modeling is THE key tool for LF-MF
antennas which must be designed anew to fit each QTH.  While you can do some
preliminary calculations to estimate Rr and such, experimental cut-and-try
is a waste of time.  Do the cut-and-try in the modeling, vastly easier!  

 

I hope this helps Ken.

 

73, Rudy N6LF