Minimum radiation-Q of polarized antennas with various source configurations

The limit curve of fundamental-limit theory provides a critical evaluation tool in terms of antenna size and performance for both systems and antenna engineers. Because the limit curve varies with source configurations and antenna geometry, one can not use the limit curve blindly. In this paper, we demonstrated the change of the minimum radiation-Q for difference source configurations and mode excitations, along with explanations of radiation physics. The results were also explained through various examples. The provided observations and concepts are useful for the design of an antenna close to the theoretical limit.