Well some progress has been made. I've ordered Low Band DXing to obtain the
Complete software CD so I can be a bit more efficient in my modeling
efforts.
I did complete my own spreadsheet to compute the mutual and driving point
Impedances for a two element setup. I agrees with some of the ON4UN
Spreadsheets that someone else has sent to me. So in my own mind I am
getting
To feel comfortable with understanding some of the physics behind phased
Vertical systems. I do have advanced degrees in Math and Engineering so
I'm no novice to complex numbers and issues around designing matching
networks.
The esoteric things like inductive and capacitive voltage dividers used in
Phasor
Networks is starting to make some sense now.
What sort of has me baffled a bit is that looking at what Array Solutions
has
Available for a triangle array Phasor, doesn't seem to take into account the
Large difference in driving point impedances when switching directions. The
Array Solutions triangle box only works for 50 ohm loads at each port to
guarantee
the phases required at each antenna port. In other words it only does the
phasor
portion of the antenna system, not the complex impedance matching required
at
each antenna. The matching networks required at each antenna will
contribute
a phase shift of the driving current.
For example for a triangle array of three 40M verticals spaced 0.29
wavelengths,
The driving point impedance calculated for direction 1 is:
EL1 = 60.16 + 12.29
EL2 = 16.42 - 43.29
EL3 = 16.42 - 43.29
Elements 2 and 3 are driven with a current magnitude of 0.5 angle of +90,
Element
1 is driven with a current magnitude of 1 angle of 0. The far field plot is
in the
Direction (or off the end) of the Element 1 direction. Elements 2 and 3 are
behind
Element 1.
If one were to switch directions and there were matching networks at the
base of
Each vertical the complete matching network would have to be changed.
I can't seem to get my head around a solution just yet. More research on my
part
Is certainly required.
This is a fun project for me so far.
Eventually some time early next year I like to get started building this
array.
I know what most folks might say just put it up and have fun but I'm the
type
Of person to know the physics and math behind what works and what doesn't
work.
Regards,
Karin K3UU
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