Radiation efficiency above unity - why?

[rfmw]

Hi,

i'm using h/f/s/s v8 and using Radiation -> Display Data -> Far Field i keep getting radiation efficiency above 1, tipically around 1.05. I'm simulating very simple geometries like ground plane antennas (currently 20000 tetrahedra). I know that i'm doing something wrong since tutor example of coaxial dipole has radiation efficiency below unity.

Plz somebody help me around this problem...

 

[boy]

I have experience that. I found out later that my model/excitation are wrong. Please check.

 

[rfmw]

Thanks for reply, but could you be a little more specific about what you meant with model/excitation?

I have a GP antenna fed by a coax cable. At the end of coax I placed a very slim cylinder, which closes the coax. I believe that the tutor coax-dipole example has the same thing. Then I selected a face of that slim cylinder facing towards the coax cable as a wave port. So what did I miss here?

 

[boy]

what u can try is to change the size of wave port. Make sure that you did not have a warning that the higher mode exists. you may also try to change the boundary condition. add more cell in PML, etc. What i did that time is just the wave port size, I make it smaller. Hope this help.