Abstract: The invention is directed to a directional coupler for coupling together a radar frequency transmitter to a combined transmitting and receiving antenna, a power absorber and a receiver. A tunable stub is employed to reflect a selected amount of transmitted energy to the local oscillator (LO) of the receiver for mixing with the incoming received signal. The coupler can be constructed from any known type RF transmission line suitable for passing or coupling signals of radar frequencies. A significant amount of the transmitter power is absorbed in a power absorbing RF load allowing only a small amount to be transmitted from the antenna and a still smaller amount fed back as LO to the receiver. The invention works equally as well on a disk type antenna and a phased array antenna.

Abstract: A radar system for monitoring the headway control distance between a vehicle equipped with a radar system of the present invention and a fixed or moving object of immediate concern in front thereof. The system employs an antenna positioned in front of the vehicle, transmitter and receiver circuits and signal processing circuits. A transmitted signal from the transmitter circuit when reflected back from an object of immediate concern is received by the receiver circuit and fed into conditioning circuits which separate the received signal into controlling signals that include the range or distance (R) to a detected object of concern, the closing rate (CR) to that object and the vehicle speed of movement (VS). Driving condition modifiers (.+-.

Abstract: A doppler radar module consisting of transmitting and receiving diodes disposed within adjacent sections of wave guide with the transmitter diode disposed a half wave length away from a shorting end of the transmitter section of wave guide, and a receiver diode disposed a quarter wave from a shorting end of the receiver portion of the guide. The receiver section and the transmitter section of the wave guides being separated by a common wall; coupling aperture disposed in the common wall substantially one wave length from the end of the transmitter section of wave guide for coupling a small portion of transmitter energy into the receiver portion of wave guide and for coupling substantially all reflected energy into the wave guide section.