Active electromagnetic structures, metamaterials, and antennas

If we are limited to rearranging passive materials such as dielectrics and metals, then the performance of antennas, artificial materials, and other electromagnetic structures that we build will always be determined by the same fundamental limitations that affect today's designs. By including active circuits, it is possible to exceed the limitations of passive structures and to build materials and devices that are not otherwise possible. One example is a thin, broadband leaky wave antenna that is free of beam squint. This structure can also be used as a broadband, electrically thin cloaking structure. Another example is a broadband parasitic array that does not suffer from bandwidth limitations caused by the delay between the elements. We have demonstrated several new concepts based on active electromagnetic structures, and have successfully implemented the non-Foster circuits that are necessary to realize them.