A fan beam antenna includes a parallel plate waveguide configured to guide electromagnetic energy of an emission beam and a reflector disposed on the parallel plate waveguide configured to reflect the electromagnetic energy of the emission beam. The fan beam antenna further includes a plurality of radiating elements disposed on the parallel plate waveguide configured to transmit and/or receive the electromagnetic energy of the emission beam and a microwave transceiver module in communication with the plurality of radiating elements.

Example embodiments relate to low elevation side lobe antennas with fan-shaped beams. An example radar unit may include a radiating plate having a first side and a second side with an illuminator, a waveguide horn, a waveguide opening, and a radiating sleeve extending into the first side of the radiating plate. The waveguide opening is positioned on the first end of the first side and the radiating sleeve is positioned on the second end of the first side. The radar unit also includes a metallic cover coupled to the first side of the radiating plate such that the metallic cover and the radiating plate form waveguide structures. The waveguide horn is configured to receive, from an external source, electromagnetic energy provided through the waveguide opening via a first waveguide and provide a portion of the electromagnetic energy to the illuminator via a second waveguide such that the portion of the electromagnetic energy radiates off the illuminator and through the radiating sleeve into an environment of the radar unit as one or more radar signals.