what happen if we have small ground plane-urgent

hello everyone...

what happen if we have a small gnd plane and also limitation size for monopole antenna if we want to increase the efficiency? it is impossible to get 50% efficiency?

hope u all can give some idea and any information to me because
i already done some other way to design the monopole antenna however i could'nt
achive the efficiency 50%

Electrically small antennas usually need a sense of humor about performance characteristics. They are convenient from a size viewpoint.

Make an antenna electrically small and the performance degrades.

so u mean that the antenna must be outside the electricall small?

can u explain more detai actuallyl i am not quite understand about electrical small antenna?it is about λ/10?