Topband: EZNEC Shunt Feed Model Gain

K4SAV RadioIR at
Wed Aug 19 07:31:13 PDT 2009

k8gg at wrote:
> When I model it as a shunt fed tower, base grounded, with 50 feet of 1.6 inch OD pipe about 27 inches
> from the center of the tower as the shunt feed rod, the gain drops to about 0 (zero) dbi. 
Modeling a gamma match for a tower is almost impossible to do in NEC2.  
It can't handle a junction of wires that have large differences in 
diameters.  Check to see if the program is making errors.  If you are 
using EZNEC, set all resistive components to zero, wire loss to zero, 
and set the ground to perfect.  Run a 3D gain plot and check the 
"Average Gain" on the main window.  This will be the amount of error the 
program is making.  No you can't just add that amount to the answer.  
Read the help file for more info.

Jerry, K4SAV

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