Small Antenna Bounds in closed analytical form

This paper offers a thorough review of the theoretical limits that define the performance of electrically small antennas, synthesizing key findings from the existing literature. Classical bounds, such as those established by Harrington and Chu, are analyzed with respect to their influence on parameters like directivity, gain, bandwidth, and efficiency. Particular focus is placed on the constraints associated with achieving super-directivity and super-gain, especially in the context of practical limitations like the bandwidth (or the Q-factor).