Abstract: Improved radar apparatus includes a rotatable antenna structure which includes an antenna disposed within a housing which is rotatably driven. Also disposed within the rotatable housing are a unitary magnetron, microwave circulator and microwave limiter device which rotates when the housing is rotatably driven. Additionally, a transmitter, such as a modulator coupled to the unitary device and a receiver also coupled to the unitary device are disposed within the rotatable housing. Preferably, the antenna is formed as a slotted wave guide antenna. Radar signals transmitted from and reflected to the antenna pass through a slotted filter which is mounted in front of the antenna. A commutator, preferably formed of slip rings and brushes, serves to electronically connect the transmitter and receiver within the housing to signal processing circuitry fixedly disposed externally of the housing, thereby permitting the housing to rotate while coupling electrical signals to and from the transmitter and receiver.