Modulated metasurface antenna and design

A modulated metasurface antenna comprising a surface wave transducer and a surface wave propagation medium, the surface wave transducer being adapted to generate a surface wave when a radio-frequency excitation signal is applied to the surface wave transducer, whereby the surface wave propagates throughout the surface wave propagation medium from the surface wave transducer to a rim of the surface wave propagation medium, the surface wave propagation medium having an electromagnetic surface impedance distribution that exhibits impedance variations that extend from the surface wave transducer to the rim of the surface wave propagation medium, the electromagnetic surface impedance distribution being non-uniform in azimuth direction on the surface wave propagation medium so that there are azimuth ranges in which the impedance variations are smallest from the surface wave transducer to the rim of the surface wave propagation medium,

• wherein the surface wave transducer has a non-uniform azimuthal surface wave power distribution so that, compared to a uniform azimuthal surface wave power distribution, a smaller amount of surface wave power is launched in the azimuth ranges where the impedance variations are the smallest.