Switchable selective backscatter modulation via the Kerker effect
We design a reflective scatterer that operates only in the backscatter direction using modulation of the Kerker effect. This being a phenomena where the resonant modes of a scattering object produce total destructive interference in the backscatter direction. Our design consists of a dielectric shell and an interior metal element that provide the required dipolar contributions for Kerker interference with angular stability. By incorporating a PIN diode, we obtain a scatterer that exhibits strong amplitude modulation in the backscattering direction that is weaker at other bistatic angles. Backscatter modulation is a key technology to connect everyday objects but can be vulnerable to eavesdropping, the device presented in this work may help guard against such flaws.