Synchronizing of distributed radar units

A radar system for a vehicle, the radar system comprising:

• a first radar unit comprising:
• a first transmitter head and a first receiver head;
• a first coupling structure coupled to the first transmitter head or the first receiver head;
• and
• a first circular polarizing waveguide launcher coupled to the first coupling structure;
• a second radar unit comprising:
• a second transmitter head and a second receiver head;
• a second coupling structure coupled to the second receiver head;
• and
• a second circular polarizing waveguide launcher coupled to the second coupling structure;
• and
• a waveguide coupled between the first and second waveguide launchers;
• wherein the first and second coupling structures are configured to redirect a portion of a signal from the respective transmitter head or receiver head that the coupling structure is coupled to in order to excite the first and second circular polarizing
• waveguide launchers respectively in order to transmit an excited circularly polarized signal to the other of the radar units via the waveguide;
• wherein upon receipt of the excited circularly polarized signal received via the waveguide, a beat signal is generated from which a frequency offset and a phase-noise calculation are made;
• and
• wherein the first and second radar units are configured to be synchronized based on the frequency offset and the phase-noise calculation.

A bumper comprising a radar system for a vehicle, the radar system comprising:

• a first radar unit comprising:
• a first transmitter head and a first receiver head;
• a first coupling structure coupled to the first transmitter head or the first receiver head;
• and
• a first circular polarizing waveguide launcher coupled to the first coupling structure;
• a second radar unit comprising:
• a second transmitter head and a second receiver head;
• a second coupling structure coupled to the second receiver head;
• and
• a second circular polarizing waveguide launcher coupled to the second coupling structure;
• and
• a waveguide coupled between the first and second waveguide launchers;
• wherein the first and second coupling structures are configured to redirect a portion of a signal from the respective transmitter head or receiver head that the coupling structure is coupled to in order to excite the first and second circular polarizing waveguide launchers respectively in order to transmit an excited circularly polarized signal to the other of the radar units via the waveguide;
• wherein upon receipt of the excited circularly polarized signal received via the waveguide, a beat signal is generated from which a frequency offset and a phase-noise calculation are made;
• and
• wherein the first and second radar units are configured to be synchronized based on the frequency offset and the phase-noise calculation.