Adaptive control and optimization of electromagnetic radiation, attenuation, and scattering using self-adaptive material systems

Adaptive control of radiation and scattering by integrated antenna arrays in the long-wavelength limit is investigated. A hybrid active/passive system with embedded control logic is considered and analyzed as a synthetic composite medium with adaptive constitutive parameters. Optimal control techniques yield the transfer function of the controller for a given internal or external stimulus and cost function. The method is applied to the minimization of radiated or scattered power at large distance. A limiting condition for omnidirectional power reduction is derived. A chequered planar array of interleaved subarrays for wave conditioning in reflection and transmission is analyzed in detail. Its dyadic Green function, impedance, equivalent permittivity, and reflection, transmission and radiation coefficients for general transfer functions are calculated. For random configurations, the effective permittivity and frequency response of the reflection and transmission by a free-standing slab of the self-adaptive medium are analyzed. The results may find application in the design and operation of electromagnetic smart materials.