Broadband Application of High Impedance Ground Planes

Electrical conductors have long been the only materials available to antenna designers for reflecting structures. However, recently reported high impedance ground plane (HIGP) structures offer a possible alternative. Within a limited frequency stopband, the high impedance structures create image currents and reflections that are inphase with a source rather than out-of-phase as for a PEC surface. Also, the high impedance structures suppress surface waves while surface waves propagate on PEC surfaces. This research explores broadband antenna applications for HIGP structures. A broadband surface mount antenna is applied to both a homogeneous narrowband HIGP and a spatially varying broadband HIGP design. Measurements reveal the ground plane alters the fundamental radiating modes of the antenna and show high frequency regions of the ground plane short out low frequency energy in the antenna. Novel integrated antenna/ground-plane structures are also introduced and analyzed. Basic high impedance elements are linked to form larger broadband antenna elements within the ground plane itself. The antenna/ground-plane structure becomes a broadband receive antenna that can be fully integrated into a PEC ground plane surface.