On the efficiency and gain of antennas
The fundamental limits of the gain and e±ciency of an antenna are explored. These are very important quantities for, e.g., superdirective arrays. The antenna is in this paper con¯ned in a sphere and all of the currents are assumed to run in a material with a given conductivity. It is shown that one can ¯nd the current distribution in the sphere that optimizes the gain, given the frequency and the
