Radiation Efficiency is Greater Than 1.....What????

[hookups1534]

Hello,

I am simulating a reflectarray antenna in CST. I am feeding the reflectarray with a cos^q(theta) model feed pattern far field source using the I-solver. Problem is when i get the results for the far field, i get an error at the end of the solver run that says the radiated power is greater than the excitation power (accepted power), leading to an efficiency greater than 1. What could cause this, my first thought was the PML boundaries. I am using the default distance of lambda/8 and my bounding box didn't add any distance to that.

Does anyone know how CST could give an efficiency greater than 1 and what could be done to fix it? Thanks.

Added after 3 minutes:

Nevermind guys, I just found a great post about this problem, see below if you have any problems similar and if anyone has anything to add to this, please feel free, thanks.

 

[abdoeng]

hi hookups
i already simulate reflectarray using CST,many types
could send me your model,may i check it
impossible,that radiation efficiency more than 100%

 

[ravi8331]

which type of feeding u used in ur structure???
which type of material u used in antenna material?
what r the properties of material used for antenna ?

plz also mention the loss tangent in material define case???
if u used coaxial feed n outer conductoe used any dielectric material then u must mention the material loss after that i think efficicncy become less than 100%.