摘要
用空间波法测量无限大半空间模拟介质板的复介电常数 ,包括金属板定标法与双极化法 ,测量中同时接收前向散射的振幅和相位 ,实验在X波段进行。该文的金属板定标法本质上是自由空间中的长试样法 。
The dielectric constant of a board simulating the medium in half space is measured in the laboratory using the space wave method including the metal-scaling method and the dual polarization method The experiment is performed in X frequency range,the amplitudes and the phases of the received fields are measured simultaneously The dielectric board consists of paraffin,plaster and graphite First,the scattered fields by different Fresnel zones in the board are calculated by Kirchhoff formula It is concluded that the area larger than 10 Fresnel zones can be approximately regarded as infinitely large The thick of the board is determined by the attenuation coefficient of the elctromagnetic waves After repeatedly measuring the dielectric constants in the waveguide for different prescriptions,the weight ratio in the board is chosen as paraffin:plaster:graphite=2 38:1:1 8,in which case the attenuation is desired The thickness and the area of the board are chosen as 10cm and 135cm×105cm The experiment frequency is 9 965GHz,the 3dB half width of the wave bean is 9°。The microwave receiver(Atlanda 1780) receives the phases and amplitudes of the reflected fields in the specular direction In the metal-scaling method,transmitting and receiving are performed in a same polarization,the reflection coefficient of the medium is obtained by comparing the phases and amplitudes of the fields reflected by the medium board and a metal board,then the permittivity is deduced from the reflection coefficient The incident angle is adopted as 15°in the metal-scaling method,the measurements indicate that the results using parallel polarization is better than that using vertical polarization In the dual polarization method,however,the incident angle is taken to be 60°,a wave with both vertical and parallel polarizations is transmitted by an inclined horn,the amplitude and the phase of the reflected field in the specular direction is received for each polarization respectively A simple formula to deduce the dielectric constant
出处
《遥感学报》
EI
CSCD
1997年第1期40-45,共6页
NATIONAL REMOTE SENSING BULLETIN
基金
国家重大自然科学基金资助项目!:4949340 1
关键词
空间波
长试样
介电常数
镜向反射
微波遥感
Space waves,Long samples,Dielectric constnat,Phase method,Specular reflection,X freqency range
