Low elevation sidelobe antenna with fan-shaped beam

A vehicle radar system comprising:

• a plurality of radar units coupled to a vehicle and configured to use radar signals to measure an environment of the vehicle, wherein at least one radar unit from the plurality of radar units comprises:
• a radiating plate having a first side and a second side, wherein the radiating plate includes an illuminator, a waveguide horn, a waveguide opening, and a radiating sleeve that are formed into the first side of the radiating plate, wherein the waveguide opening is positioned on a first end of the first side and the radiating sleeve is positioned on a second end of the first side, and the first end of the first side is opposite the second end of the first side;
• and a metallic cover coupled to the first side of the radiating plate such that the metallic cover and the radiating plate form a plurality of waveguide structures and enclose the illuminator and the waveguide horn, wherein the illuminator has an arc-shape with a concave surface oriented toward the radiating sleeve and an end opening of the waveguide horn, and wherein, during radar signal transmission by the at least one radar unit, the waveguide horn receives, from an external source, electromagnetic energy provided through the waveguide opening via a first waveguide;
• and
• provides a portion of the electromagnetic energy out of the waveguide horn through the end opening of the waveguide horn and in a direct path toward the concave surface of the illuminator via a second waveguide such that the portion of the electromagnetic energy reflects off the concave surface of the illuminator and subsequently radiates through the radiating sleeve into the environment as one or more radar signals.

A method of operating a radar unit comprising:

• transmitting, using the radar unit, a plurality of radar signals into an environment, wherein the radar unit comprises:
• a radiating plate having a first side and a second side, wherein the radiating plate includes an illuminator, a waveguide horn, a waveguide opening, and a radiating sleeve that are formed into the first side of the radiating plate, wherein the waveguide opening is positioned on a first end of the first side and the radiating sleeve is positioned on a second end of the first side, and the first end of the first side is opposite the second end of the first side;
• and a metallic cover coupled to the first side of the radiating plate such that the metallic cover and the radiating plate form a plurality of waveguide structures and enclose the illuminator and the waveguide horn, wherein the illuminator has an arc-shape with a concave surface oriented toward the radiating sleeve and an end opening of the waveguide horn, and wherein, during radar signal transmission by the radar unit, the waveguide horn:
• (i) receives, from an external source, electromagnetic energy provided through the waveguide opening via a first waveguide, and (ii) provides a portion of the electromagnetic energy out through the end opening of the waveguide horn and in a direct path toward the concave surface of the illuminator via a second waveguide such that the portion of the electromagnetic energy reflects off the concave surface of the illuminator and subsequently radiates through the radiating sleeve into the environment as the plurality of radar signals;
• and receiving, using the radar unit, reflections corresponding to the plurality of radar signals from the environment;
• and processing the reflections to detect one or more objects in the environment.