| 摘要 |
Method and arrangement for determination of attenuation of microwaves and/or phase rotation during transmission through a material according to the invention utilizes at least two pairs of antennas 12, 13; 14, 15 in which the first pair of antennas 12, 13 is positioned so that it is displaced along a line through the two antennas 12, 13 relative to the second pair of antennas 14, 15 for the distance equal to lambda/4 or an odd multiple thereof in which lambda is the wavelength of the microwave signal. The microwave signal is made to pass through a measurement channel containing in series the first antenna pair 12, 13, a modulator 7 in which the microwave signal is modulated with a modulation signal of lower frequency f1 then the microwave signal's frequency f0 and the second antenna pair 14, 15, and a reference channel. The microwave signal obtained from the measurement channel is compared with the microwave signal obtained by the reference channel and with the applied modulation signal in a signal processing unit 8, 27. <IMAGE> |
