[TowerTalk] Resonant frequency of a tower

[K4SAV]

Does anyone have a good test method to determine the resonant point(s) 
of a tower structure?  The system is sufficiently complex that I don't 
think I can ever get an accurate model for simulation and I think it 
will have to be determined experimentally.  I expect multiple resonance 
points, probably between 1.5 and 4 MHz, and high loss due to the tower 
not having a radial system except for what is provided by the ground 
system and cables.

The reason for this is that I am trying to plan a location for an 80 
meter four square, a 160 meter top loaded vertical, and an EWE array on 
my property.  Simulations show that resonance of the tower anywhere 
close to 80M or 160M significantly affects the other antennas.  A 
separation of at least 500 feet is required to maintain any reasonable 
resemblance of a decent pattern if the resonant point occurs in one of 
these bands.  I would like to not have to maintain this kind of 
separation and hope maybe I can detune the tower, but I need a good test 
method.

I know the four square and 160M vertical affect the EWE array, but I can 
simulate this.

Jerry, K4SAV