Using equivalent Near Field Sources (AP Card)

Altair Forum User

Hi, 

 

I am trying to create a Large array using the equivalent near field data on a sphere  encapsulating the single element.

 

i did using the AP card in editfeko. However, after the simulation run, I did a check on the .out file to verify the power of the different near field sources, and It varied from -1 watt to 0.6 watt.

 

My questions:

 

1) why is there a negative power for some of the near field sources, 

2) why is there a variation in the near field source power?

 

thanks.

Mel

Hi CAW4933

 

FEKO automatically computes the mutual coupling for accurate source power. The negative power can happen if the sources are close together and it depends on the magnitude and phase of each source.

 

One would see the same in e.g. a physical antenna array - if you model say a few dipoles close together the source powers of some could be negative.

If you space them several lambdas apart you won't see much difference in the source powers.