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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 a

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.

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What is claimed is: 1. A security system comprising:a first microwave sensor having a linearly polarized antenna with an electric field oriented at 45 degrees with respect to the horizon the linear polarized antenna transmits a microwave signal parallel to the plane of the horizon and receives refle

What is claimed is: 1. A security system comprising:a first microwave sensor having a linearly polarized antenna with an electric field oriented at 45 degrees with respect to the horizon the linear polarized antenna transmits a microwave signal parallel to the plane of the horizon and receives reflected signals, wherein the transmitted microwave signal has an electric field at 45 degrees to the plane of the horizontal; anda second microwave sensor, the second microwave sensor further comprisingan oscillator configured to generate a microwave signal at a pre-determined frequency;a linearly polarized antenna having an electric field oriented at 45 degrees with respect to the horizon configured to transmit the microwave signal parallel to the plane of the horizon and to receive reflected signals, wherein the transmitted microwave signal has an electric field at 45 degrees to the plane of the horizontal;a signal processor coupled to the antenna and configured to process the reflected signals to determine a presence of a moving object; anda mixer coupled to the antenna and the oscillator and configured to mix the reflected signal with a portion the transmitted microwave signal to generate a corresponding inteimediate frequency wherein the linear polarized antenna of the first and second microwave sensors face each other and wherein the electric fields of the linear polarized antenna of the first and second microwave sensors are perpendicular to each other.