A New Modal Approach for Evaluating $Q$ -Factors of Antennas.

This paper proposes a new modal approach for evaluating $Q$ -factors of antennas based on newly introduced XeR/XmR modes rather than characteristic modes (CMs). In our new approach, $Q$ -factors could be represented as direct linear superpositions of eigenvalues of XeR and XmR modes. We validate the accuracy of the new formula for $Q$ -factors by studying two canonical wire antennas. Moreover, the relations between XeR/XmR, TE/TM, and Xe/Xm modes are presented, which show interesting properties. It is found that eigenvalues of XeR/XmR modes reveal useful information about minimum $Q$ -factors. Compared with the CMs, some disadvantages of the proposed modes are also discussed. [ABSTRACT FROM AUTHOR]