Abstract
A dual semi-circular microstrip patch antenna implemented on a
biodegradable substrate is presented for operation in the
[863-873]-MHz and [2.4-2.5]-GHz frequency bands. To cover these
frequency bands, two semi-circular patches are compactly integrated onto
a biodegradable cork tile, commonly found as support in laminate
flooring, serving as a substrate. Thereby, the antenna tile may be
seamlessly embedded as a sublayer of the floor structure. A higher-order
mode is generated by applying via pins in the antenna topology, to
produce a conical radiation pattern with a null at broadside and
sectoral coverage in the vertical plane. As such, the concealed-floor
antenna covers all azimuth angles of arrival in smart houses. The
antenna performance is fully validated, also when the tile is covered by
different PVC sheets. Owing to the supplementary design margins, the
antenna impedance bandwidth remains covered. Moreover, the radiation
patterns are measured in various elevation planes. In stand-alone
conditions, a radiation efficiency and a maximum gain of 74.3 % and 5.8
dBi at 2.45 GHz and 48.1 % and 2 dBi at 868 MHz are obtained. Its omni
directional coverage in the horizontal plane, stable performance on the
inhomogeneous and biocompatible cork substrate and for various
inhomogeneous superstrates and its low-profile integration make the
proposed antenna an excellent candidate for smart floors and smart
houses.