Tetsuji Uebo

Standing Wave Radar Capable of Measuring Distances down to Zero Meters

Various types of radars have been developed and used until now-such as Pulse, FM-CW. and Spread Spectrum. Additionally, we have proposed another type of radar which measures distances by using standing wave. We have named it as Standing Wave Radar. It has a shorter minimum detectable range and higher accuracy compared to other types. However, the radar can not measure distances down to zero meters like other types of radars. Minimum detectable range of the standing wave radar depends on a usable frequency range. A wider frequency range is required if we need to measure shorter distances. Consequently, we propose a new method for measuring distances down to zero meters without expanding the frequency range. We use an analytic signal, which is a complex sinusoidal signal. The signal is obtained by observing the standing wave with multiple detectors. We calculate distances by Fourier transform of the analytic signal. Moreover, we verify the validity of our method by simulations based on numerical calculation. The results show that it is possible to measure distances down to zero meters. In our method, measurement errors are caused by deviations of position and gain of the detectors. They are around 10cm at the largest if the gain deviations are up to ±1% and the position deviations are up to ±6% of the spacing between the detectors. Prevalent radars still have a common defect that they can not measure distances from zero to several meters. We expect that the defect will be eliminated by putting our method into practical use.

Measurement of distance and velocity of a moving target by short-range high-resolution radar utilizing standing wave

In this paper, we propose a radar using standing wave, and describe the measurement principle and experiment results. This radar does not use a time delay like usual radars but uses the amplitude of the standing wave. As a result of experiments, this radar could measure the distance and velocity of a moving target using bandwidth of only 76 MHz permitted by the specification of low-power radio equipment to detect moving objects (24 GHz band). The bandwidth of the radar is narrower than that of a millimeter wave radar.