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HFSS accepted power puzzle in a lossless matched antenna array

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Newbie level 2
Dec 7, 2010
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Hi all,

i've designed an two port antenna array in HFSS. The antenna is CPW, and each antenna is fed by a 50 Ohm coaxial cable, which is excited by a wave port. The antenna is lossless, using pec and no dielectric loss. at operating frequency, S11 and S22 is around -25dB and S12 is around -14dB. Each wave port is renormalized to input impedance (Z11,Z22) at the port, which is not 50Ohm but something else.

Th puzzle is, in HFSS, i make only 1 port have input power, which is 1W, the other port has 0 input power. Then i compute the far field parameter over a sphere, i found the accepted power is only 0.7Watt,(input power is 1 watt) but since my s11,s22 and s12 are pretty small, the ports are matched, i should expect something close to 1W. I wonder where does the power go?

Any answer will be appreciated. Thanks!

HI, i figured it out. The port renormalization (wave port) doesn't do anything to the calculation of accepted power. The value is the same before and after the renormalization, quite weird.

Hi alberthyc,
Could you share how you figured out where the remaining power went? I'm trying to impedance match a 5-element dipole array but with no luck. I tried to match it with Active Z re and im values, but I still get power accepted much less than power incident.


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