NEC-LIST: Current Source

Hello everyone,

A) Can anyone suggest any better solutions/or anything wrong with
current source below :

I try to feed my phased array with current sources in 3 different
methods:

    1) Put a big resistor (1E+6) in series with voltage source.
    Found: Due to huge loading resistance->Power loss, efficiency=0.

    2) Using NT card where y11(Re,Im)=y22(Re,Im)=(0,0) and
       y12(Re,Im)=(1E-6,0).
    Found: Different current values (Re,Im) at feeding segment in
    comparison to case (1) above, but the calculated mag of both
    are the same.

    3) Using TL with 1/4 wavelength line connecting source
    Found: Because of frequency dependent->no further interest !

I can easily vary the phase by changing the voltage source values,
this respectively cause changes in current (a simple vector plot of
current input vector in complex domain is enough to show changing
phase). However, due to the ~90 deg phase shift between Z and Y (1/Z),
therefore, case (2) takes Im axis as reference, whereas case (1) takes
Re axis as reference.[Try a simple 2 dipole array, you will see this]

I was expecting both methods (1 and 2) produce the same current at
feed (or at least closely match one another) but it is not true at
all. Got confused here !!!!

B) What is the standard method to generate a current source with NEC2?
Wondering how EZNEC/ELNEC or SuperNEC generate current source?

Thank you very much for your help.

Quang
Received on Thu May 11 2000 - 03:54:45 EDT