Radio detection and ranging (radar) is used to sense angle, range, and velocity of (moving) scatterers in the environment. Radar sensor capabilities of merit include maximum range and solid angle, as well as angular, range, and velocity resolution. Range and velocity are typically detected through pulse delay ranging and the Doppler effect, or through the frequency modulated continuous wave (FMCW) technique and range differentiation. Angle is detected by scanning the volume with a highly directive beam. Scanning is accomplished mechanically or electronically, by rotating an antenna or steering the beam of an array, respectively.
Researchers at the University of Michigan have developed a radar system comprising an orthogonal frequency division multiplexing (OFDM) modem and a frequency scanning antenna. The frequency antenna radiates the OFDM modulated radio frequency energy. The directionality of the frequency scanning radar is dependent on the sub-band carrier frequency of the OFDM modulation. The OFDM sub-band can carry a pulse-Doppler radar waveform for detection of target range and velocity. The frequency scanning antenna is comprised of a slotted waveguide with helical and a serpentine waveguide feed. The system may also include a transmit/ receive (T/R) module that up-converts and amplifies the OFDM modulation, and outputs the amplified signal to the frequency scanning antenna. Conversely, the T/R module may amplify and down-convert the radio frequency signal from the antenna and output the signal to the OFDM modem.
Applications and Advantages
- autonomous landing guidance
- radar sensor for long-range autonomous cruise control and forward collision warning systems
- high resolution millimeter-wave imaging
- low cost
- size reduction
- low-profile angle detection
- can simultaneously measure multiple scanning angles