常用的介电常数，包括日常接触到的化学物质，很全很强大-useful things about E

在设计microstrip patch antenna:输入中心频率、介质基板厚度和介电常数，得到 patch的设计参数和馈电位置(In the design microstrip patch antenna: input center frequency, dielectric substrate thickness and dielectric constant, get patch design parameters and feed position)