Northrop Grumman Systems Corporation

Thomas E Szmurlo

Warren E Guthrie

David L Richardson

Roger Brunner Williams

Robert Edward Rozak

Mitchell F Radich

James Jensen

A monitor tag having a radio frequency transmitter and a patch antenna. The antenna is in communication with the transmitter and has a first conductive patch and a second conductive patch substantially parallel to each other, and separated from each other by a dielectric material in contact with both patches and having a thickness sufficient to create a gap between the patches wherein the radiation resistance will be controlled during operation of the antenna. The first conductive patch has a dimension of one-quarter or one-half wavelength, depending upon available space and desired pattern. Because the electric field is launched from the gap between the patches and is highly concentrated, bringing the monitor tag close to a metal object or attaching it thereto will have minimal impact on the impedance of the antenna. The monitor tag can be used for a number of purposes including asset protection and identification by affixing respective tags with conventional transmitters to respective metal and nonmetal articles and transmitting chosen respective information about each article. Of particular applicability is a monitor tag device worn by a person such that the wearer can be monitored with respect to chosen parameters as developed for observing or regulating and transmitted or received by the antenna of the present monitor tag invention.

Monitor tag with patch antenna

A single antenna poly-frequency Continuous Wave (CW) Doppler radar system having leakage cancellation. The system provides for transmitting a plurality of carrier frequency signals and receiving the return signals by means of a single antenna coupled to an antenna interface through which a portion of the transmitted signal may leak. The signal appearing on an output port of the antenna interface is then down-converted to an intermediate frequency (IF) signal by a stable mixing signal. The IF signal is coupled to an adder which in turn is coupled to an output. The IF signal is further split into a pair of cancellation loops for each carrier frequency signal. Each cancellation loop includes a correlator and provides for processing the IF signal with an in-phase or a quadrature-phase signal associated with the carrier frequency signal so that each pair of cancellation loops outputs a feedback signal representative of and equal to the amplitude of the leakage signal only, which feedback signal then being subtracted from the IF signal with the resultant return signal less the leakage signal then being transmitted for further processing. Preferably, a second order linear feedback circuit and phase compensation circuit is provided in each cancellation loop for processing of the IF signal. The disclosed system does not require high precision, high cost oscillators and has particular application in military radars, navigation radars and vehicular collision warning radars.

Poly-frequency CW doppler radar system with leakage cancellation and

Second harmonic distortion of a traveling wave tube amplifier with a bandwidth exceeding one octave is efficiently minimized by generating a low-power second harmonic signal, modifying it by an adaptive filter, and adding the modified second harmonic signal to the fundamental frequency input signal to the TWT. The adaptive filter is controlled by a feedback loop from the output of the TWT and is arranged to minimize the correlation between the generated second harmonic signal and the second harmonic content of the TWT output. Intermodulation distortion is eliminated in a similar manner.

Reduction of second order harmonic distortion in high power TWT

In a method for transmitting a desired parameter to a remote location, the desired parameter is first communicated to a base transmitter. Then, the base transmitter transmits a first radio signal therefrom having an unknown center frequency within a known frequency band. The first radio signal comprises information representative of the desired parameter. At a remote location, a remote receiver identifies the center frequency of the first radio signal and tunes the remote receiver to the center frequency thereof so as to facilitate reception of the first radio signal with the remote receiver. The information representative of the desired parameter may then be communicated to a desired destination.

Remote utility meter reading system

Hard-wired analog adaptive cancellation for microwave receivers to cancel the interference generated by co-located transmitter employs a circuit having two or more quadrature taps on a delay line. The least and greatest delays provided by the delay line taps are selected so that the copies of the transmitted signals provided by the respective taps bracket the timing of the portion of the transmitted signal that leaks into the collocated receiver's input. Samples of received signals corrupted by interference from the transmitter are mixed with delayed samples of a transmission reference signal to develop a cancellation signal.

Method and apparatus for hard-wired adaptive cancellation

A translator for translating GPS signals received at one location to a different frequency for ground transmission to another location uses a spread spectrum pilot tone for phase-locking the local oscillator of the ground transmitter to that of the ground receiver, thereby increasing security, enabling use of otherwise unavailable frequency spectra, allowing coherence of pilot tone and GPS signal with small coherence bandwidths, and allowing interference-free transmission of the translated GPS signal and pilot tone with the same center frequency.

Growing community of inventors

Palatine, IL, United States of America

Thomas E Szmurlo