Abstract: A vehicle positioning and tracking radar system includes a rotating antenna with a pair of spatially separated transmit feeds for simultaneously transmitting a pair of frequency-modulated continuous-wave (FMCW) electromagnetic signals having a first polarisation and a pair of spatially separated receive feeds for receiving an electromagnetic signal having a second polarisation, wherein the first and second polarisations are different from one another, such that the transmit feed and receive feed at the rotating antenna are isolated from each other; and a coded modulated transponder receives transmit signals from the rotating antenna with the first polarization and transmits a receive signal to the rotating antenna with the second polarization.

Abstract: The present invention provides a rotating antenna that can be used in combination with a coded modulated transponder as part of a vehicle positioning and tracking radar system. The antenna transmits a pair of frequency-modulated continuous-wave (FMCW) electromagnetic signals that have a vertical polarisation, for example. The transmit signals are incident on the transponder which returns or transmits an electromagnetic signal back to the antenna having a horizontal polarisation, for example. The transponder can alter the polarisation of the incident transmit signals using a known technique. The transmit and receive feeds at the antenna are cross-polarised and are therefore isolated from each other.