二端子対回路
インピーダンス行列、Z行列とも。
( V 1 V 2 ) = ( Z 11 Z 12 Z 21 Z 22 ) ( I 1 I 2 ) {\displaystyle {V_{1} \choose V_{2}}={\begin{pmatrix}Z_{11}&Z_{12}\\Z_{21}&Z_{22}\end{pmatrix}}{I_{1} \choose I_{2}}}
Z 11 {\displaystyle Z_{11}} ・ Z 12 {\displaystyle Z_{12}} ・ Z 21 {\displaystyle Z_{21}} ・ Z 22 {\displaystyle Z_{22}} の各インピーダンスパラメータは以下のとおり。
Z 11 = V 1 I 1 | I 2 = 0 Z 12 = V 1 I 2 | I 1 = 0 {\displaystyle Z_{11}={V_{1} \over I_{1}}{\bigg |}_{I_{2}=0}\qquad Z_{12}={V_{1} \over I_{2}}{\bigg |}_{I_{1}=0}}
Z 21 = V 2 I 1 | I 2 = 0 Z 22 = V 2 I 2 | I 1 = 0 {\displaystyle Z_{21}={V_{2} \over I_{1}}{\bigg |}_{I_{2}=0}\qquad Z_{22}={V_{2} \over I_{2}}{\bigg |}_{I_{1}=0}}