Study on the Relationships between Eigenmodes, Natural Modes, and Characteristic Modes of Perfectly Electric Conducting Bodies

Table 1

Summarization of modal definitions and properties.

Mode	Eigenmode	Natural mode	Characteristic mode
Current
Definition
Eigenvalue		0
Main properties	(1) is generally a complex number, while is a real number.; (2) and are generally complex, while is real.; (3) Linked to (2), and are not equiphase on the surface of PEC bodies generally, while is always equiphase.; (4) is similar but not identical to the ratios between the real parts and the imaginary parts of in general.; (5) The natural modes can exist in the absence of impressed fields, while the eigenmodes and characteristic modes cannot.