  The concepts of many optical devices are based on the fundamental physical
phenomena such as resonances. One of the commonly used devices is an
electromagnetic antenna that converts localized energy into freely propagating
radiation and vise versa, offering unique capabilities for controlling
electromagnetic radiation. Here we propose a concept for controlling the
intensity and directionality of electromagnetic wave scattering in
radio-frequency and optical antennas based on the physics of Fano resonances.
We develop an analytical theory of spatial Fano resonances in antennas that
describes switching of the radiation pattern between the forward and backward
directions, and confirm our theory with both numerical calculations and
microwave experiments. Our approach bridges the concepts of conventional radio
antennas and photonic nanoantennas, and it provides a paradigm for the design
of wireless optical devices with various functionalities and architectures.
