Design an antenna insensitive to environmental changes

Dear all,

I have a question on antenna design: how could we design an antenna which is insensitive to environmental changes, such as proximity objects? I know, I can try broadband antennae, but there is no guarantee they will work well. I can also try to put a piece of high-dielectric constant material in front of the antenna, and consider its effect in my antenna design. However, the radiation efficiency will be reduced. Do you have any ideas?

regards,

Any suggustions? Please,