Analysis of Radio Wave Propagation Characteristics in Rotating Environment and Its Application in Tire Pressure Monitoring
Xiaoping Wang · Yibiao jishu yu chuanganqi · 2009
The mathematical relationships in rotating environment,i.e.the distance between transmitter and receiver as well as the unobstructed line-of-sight space angle at any time,were derived,which were also related to the parameters of rotation radius,velocity,etc.The relationship between the rotation Doppler frequency shift and working frequency,velocity,etc.were established.The results show that the Doppler frequency shift in rotating environment varies periodically like the cosine function curves.Taking TPMS(tire pressure monitoring system) as an example,the impedance variations of transmitting antenna as well as the gains directed towards receiving antenna were given.The results show that the antenna radiation patterns apparently change with tire rotating.EMW(electromagnetic wave propagation) polarization characteristics from rotating transmitter were analyzed.The results show that the rotation changes the polarization characteristics of the transmitting linear polarization wave.A new TPMS was designed.The test results show that the receiving probabilities of successful data frame transmission are improved.