Manipulating the scattering pattern with non-Hermitian particle arrays

We show that an array of non-Hermitian particles can enable advanced manipulations of the scattering pattern, beyond what is possible with passive structures. Active linear elements are shown to provide zero forward scattering without sacrificing the total scattered power, and by adding more particles, it is possible to control the zero-scattering direction at will. We apply our theory to realistic implementations of scatterer arrays, using loaded dipole antennas in which we tune the load impedance and investigate the stability of these arrays based on a realistic dispersion model for the gain elements. Finally, we discuss the possibility of controlling multiple frequencies to enable broadband control of the scattering pattern.