Raytheon Company

Zachary Dunn

Harry B Marr

Thomas Comberiate

Benjamin Plotner

An apparatus includes an absorbing material configured to absorb electromagnetic energy. The apparatus also includes a thermochromic material in or on the absorbing material, where the thermochromic material is configured to change one or more visible characteristics based on the absorbing material being heated above a specified temperature threshold. The absorbing material may be configured to absorb radio frequency signals or microwave signals. The one or more visible characteristics may include at least one of: color and opacity.

Heat-visualizing radio frequency (RF) or other electro-magnetic absorber

A method of beamforming is provided. A single non-linear equalization (NLEQ) coefficient set is generated in beamspace, the single NLEQ coefficient set configured to characterize non-linear behavior of a system having an array of N elements. M parallel digital signals are received, for transmission by N channels, respectively, the N channels corresponding to the N elements. Each of the M respective parallel digital signals are equalized, using an NLEQ filter based on the single NLEQ coefficient set, wherein the single NLEQ coefficient set is used for each of the N elements and wherein the equalizing is configured to generate a set of M linearized parallel digital signals. Using a single summer, the M linearized parallel digital signals are summed, to produce one or more beamspace channelized output signals.

Intermodulation suppression in phased arrays using volterra filters

System and method for beamspace nonlinear equalization in a plurality of parallel channels includes: receiving M parallel signals for transmission by N channels, respectively, wherein M is an integer greater than or equal to 1 and N is an integer greater than 1; performing a linear transfer function on each of the M parallel signal by a finite impulse response (FIR) filter; adding FIR filter tap outputs to each M parallel signals, respectively; phase shifting an output of a respective FIR filter per each of the M parallel signals to generate M intermediate channelized output signals per each of the N channels; summing, by a single summer, the M intermediate channelized output signals across the N channels to produce M channelized polyphase output signals; serializing the M channelized polyphase output signals to generate serialized M polyphase output signals; and equalizing the serialized M polyphase output signals to produce a linearized signal in beamspace.

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Wylie, TX, United States of America

Zachary Dunn