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Old October 29th 05, 04:41 PM
Frank's
 
Posts: n/a
Default Problem with nec2

...........................
If I calculate the gain with the formula:

4 * Pi * r^2 * |E|^2
Gain = -----------------------
P_in * 2 * 120 * Pi

by using the E-Field magnitude values from nec2's output I get also
those very high values. (?)


PS, also confused by your formula. Which Value of E are you using? Are

you
The formula should be correct:
I just use the magnitude value of the E Field. The intensitiy
W_rad is then 0.5 * |E|^2 / Z_w (E and H are in phase and
orthogonal in the far field)

The radiation density U is then r^2 * W_rad (Unit: Watt per solid angle)

The radiation density U_0 of an isotropic radiator with a total radiated
power P_rad is: P_rad / (4 * Pi).

The gain is then U/U_0 (or in dBi: 10*log(U/U_0) ).


Ok, now I understand.


trying to calculate the "Total radiated power" (TRP)? If so you need to
integrate the power density over a spherical region. The calculation is

Yes, but nec2 shows the total radiated power in its output.


Have checked "Power Budget" output, and confirm that using it for TRP is
valid in free space only.


No thats no true. In the output file I can see E_phi as well as E_theta

for
every combination of phi and theta (for every frequency).


I agree, my problem is that NEC-Win Pro cannot use this information for its
graphical utilities.

I use the programm Xnecview to view the pattern and it has problems if you
don't have points over the full sphere.


Ok, I see that Xnecview will only run under Linux/Unix OS. My version of
NEC only runs in Windows.

is that I normally do not use gain averaging. Also using 1 degree

The average gain (over the full sphere) should probably be 1 (or 0 dBi).
I get 0.991.


Regards,

Frank