English: An illustlation to explain the characteristic impedance of coaxical cable. D is the inside diameter of the metalic shield, d is the diameter of center core and ε is the relative permittivity of the dielectric material (insulating material).
{{Information |Description={{en|1=An illustlation to explain the characteristic impedance of coaxical cable. D is the inside diameter of the metalic shield and d is the diameter of center core.}} {{ja|1=同軸ケーブルの特性インピーダンスを�