Radiation Efficiency warning in reflectarray antenna simulation

[Nakisa Esmaeili]

I am simulating a reflectarray antenna in CST. I am feeding the reflectarray with a Horn antenna using the integral equation solver. Problem is when i get the results for the far field, I get a warning 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. The boundary conditions are open and space for x min,x max,y min ,y max and z max and et=0 for z min...What is the problem?

 

[volker@muehlhaus]

Maybe you integrate over the radiation sphere twice.
What are your ranges for theta and phi?

 

[Nakisa Esmaeili]

Maybe you integrate over the radiation sphere twice.
What are your ranges for theta and phi?

I haven't set any specific range for theta and phi