Active negative impedance loaded EBG structures for the realization of ultra-wideband Artificial Magnetic Conductors

A new design methodology is introduced for an ultra-wideband Artificial Magnetic Conductor (AMC) that is based on loading the elements of Electromagnetic Bandgap (EBG) structures with active devices. The types of active loads used for this application belong to the class of devices known as Negative Impedance Converters (NICs). NICs are active two-port networks for which the impedance looking into one port is the negation of the impedance connected to the other port scaled by the impedance conversion coefficient of the device. Several design examples will be presented that demonstrate the considerable enhancement in bandwidth that can be achieved, compared to conventional passive AMC surfaces, by using EBG structures actively loaded with NICs.