一、引言相对介电常数ε_r 和损耗角正切 tgδ是电介质的主要特性参数。在微波工程中,精确地测量这些参数是非常重要的。最常见的测量方法是短路波导法。所谓短路波导法是把填充介质的波导终端短路,波导中传播的是驻波,电介质试样的长度一般取1/4λ_(ge)的奇数倍。这种方法存在一些缺点,例如,对于 tgδ较小(10~(-3)数量级)的电介质,由于波导短路后驻波系数很大,波节点电平很低,因此,如果测量线探针耦合太浅,则信号难以检测到,信号也 I. Introduction Relative permittivity ε_r and loss tangent tgδ is the main characteristic parameters of the dielectric. In microwave engineering, it is important to accurately measure these parameters. The most common measurement method is short-circuit waveguide method. The so-called short-circuit waveguide method is to fill the dielectric waveguide terminal short-circuited, the waveguide is the standing wave propagation, dielectric length of the sample generally take 1 / 4λ_ (ge) odd times. This method has some drawbacks. For example, for a dielectric with a small tgδ (on the order of 10 -3), since the standing wave coefficient is large after the short circuit of the waveguide and the node level of the wave is very low, if the measurement line probe is coupled Too shallow, then the signal is difficult to detect, the signal is also