  In this letter, an approach for designing a tunable and steerable antenna is
presented. The antenna model is based on a wideband bow-tie radiating element
mounted above an active Artificial Magnetic Conductor (AMC). The AMC geometry
consists of a Frequency Selective Surface (FSS) printed on a thin grounded
dielectric slab in which some chip-set varactor diodes are placed between the
metallic elements and the backing plane through vias. The resulting antenna can
be tuned over the S-Band by simply changing all varactor capacitances through
an appropriate biasing voltage. Moreover, this structure can operate a beam
scanning over each working frequency by applying an appropriate biasing voltage
to the active elements of the AMC surface in accordance to leaky radiation
principles. The low profile active antenna is characterized by an overall
thickness of 5.32 mm, which corresponds to approximately lambda/24 at the
centre of the operating band.
