UWB magneto-dielectric ground plane for low-profile antenna applications

In low-profile applications, the antenna is often positioned very closely to an electrically conducting surface, or ground plane. Such a ground-plane backing significantly degrades antenna performance when the electrical height is less than A115. Existing approaches, such as lossless electromagnetic bandgap (EBG) structures and artificial magnetic conductors (AMC), tend to operate over a small bandwidth. This paper discusses two alternative ultra-wideband (UWB) approaches that laminate the ground plane with 'special magneto-dielectric (or ferrite) layers. The first approach employs a ferrite layer with a high r/rratio to produce an in-phase reflection, similar to that caused by a perfect magnetic conductor (PMC). The second approach adapts a lossy ferrite with similar values of relative permeability, uir, and relative permittivity, 6r. Radiation enhancements achieved via these ground-plane treatments will be demonstrated by simulated and measured examples. Design guidelines based on a parametric study will also be discussed.