A vehicular radar sensing system includes a radar sensor that includes a radiation slot sheet, a wave port sheet, and a waveguide sheet sandwiched between the radiation slot sheet and the wave port sheet. The sheets are joined together. The radiation slot sheet includes at least one transmitter that transmits radio signals and at least one receiver that receives radio signals. The waveguide sheet guides the transmitted radio signals from the radiation slot sheet to the wave port sheet and guides reflected radio signals from the wave port sheet to the radiation slot sheet. The transmitted radio signals are provided to the environment via at least one wave port of the wave point sheet. The reflected radio signals are received from the environment at the at least one wave port.