How is it theoretically possible that radiation efficiency is higher that 100%. I am working on hfss 14.0?
Radiation efficiency is the ratio of output power to input power and in terms of magnitude is between 0 and 1. What you are seeing is not correct and is due to your simulation parameters. This may be caused by too coarse a mesh, your airbox is too small (if you are using one), or your boundaries are incorrectly assigned. These are not the only possible answers as to why your simulation is not running properly. More information about the specific simulation would be required before a definitive answer can be given. Either way, your efficiency should not be above 1 (100%). How much above 100% is it? Is it within an acceptable error range? Are you using loss-less, lossy, or gain media for the antenna?
The simulation method is to be utilised very carefully, otherwise it will cheat us. Unexpectable out come is result of the non consideration of hypothesis/limitations. Hence one has to use very carefully. It is simply mathematics. It can give you 1=2 E.G. zero multiplied by1 and zero multiplied by 2 both provides outcome as zero, does it mean 1=2? Hence use simulation tool carefully
Is there any active circuit/device within the design ? check your antenna design input resistance when you have no losses (all PEC, no dielectric loss , etc ) and check the efficiency (which should be 100%) ? if you are seeing some negative values, then you need to check your simulation setting, also if your antenna is electrically small ( input resistance very small), it could have some numerically stability issue which causes some negative input resistance values.
Efficiency can never be more than 100%. Even to get 100% you require a perfect environment. I recommend you to simulate the antenna at least 1.5 times higher frequency as desired. (solution frequency 1.5Xfo). Secondly use finite conductivity instead of PEC for metal, and in finite conductivity assign copper material to be more realistic.
Even if the radiation efficiency that is the ratio of the radiated power to the accepted power given is theoretically in maximum 100%, in simulation, it can be more if you didn't define correctly the boundary limits or the port to be displayed.
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