A microwave sensor comprises an oscillator configured to generate a microwave signal at a pre-determined frequency, and an antenna configured to transmit the microwave signal and/or to receive reflected signals. The antenna is linear polarized at 45 degrees and the transmitted microwave signal has an electric field at 45 degrees to the plane of the horizontal. The microwave sensor further includes a signal processor coupled to the antenna and configured to process the reflected signals to determine a presence of a moving object.