Design Of Millimeter Wave Interference Effects Equivalent Measurement System

An indoor interference effects test system of a passive millimeter wave detector is designed in this paper, which is used to test the performance and interference effects of jammers. The principle is based on the experimental interference results of a passive millimeter wave detector with a jammer outdoor, and the outdoor space loss of millimeter wave energy is equivalent to the propagation medium attenuation loss indoor. The system includs a small anechoic chamber, some medium attenuators,a transmitting and receiving platform, a cutting-wave wheel modulator and out-signal acquisition and processing module of the passive millimeter wave detector. Signal acquisition and system control are with STM32MCU platform, and signal processing results are displayed with PC.First of all, the electromagnetic wave propagation path loss model in free space is analyzed and the electromagnetic wave propagation loss is studied in the medium in detail, then several key parameters are simulated, which affect the millimeter wave propagation loss in absorbing material. Foam mixed with graphite powder is selected as the tested material, and the transmission loss is tested in millimeter wave band.Secondly, the principle of passive millimeter wave detector and the method of jammer interfere detector is focused. According to the outdoor interference effects, interference energy signal waveforms received by the detector under different detecting ranges are collected. Millimeter wave energy space attenuation is obtained by Friss propagation equation, then the millimeter wave energy space distance loss is equivalent with the millimeter wave energy propagation loss in the medium.Again, an indoor millimeter wave interference effects measurement system is designed in detail, the shape and size of small anechoic chamber are analyzed, the size of dead space is simulated and calculated,medium attenuators zone is designed with equivalent methods. The out-signal acquisition and transmission module of passive millimeter wave detector is debugged and the acquisition accuracy is obtained. The cutting-wave wheel modulator is debugged as well and the speed contrloble range and measurement error are received.Finally, a complete test system is formed indoor and some experiment are test with a detector and some jammers. In order to observe the results conveniently,test results are displayed on PC, and compared with results of the actual field interference.