Nonreciprocal Time-Invariant Leaky Waves Enabled by Magnetized Plasma

This work demonstrates a passive time-invariant leaky-wave antenna exhibiting nonreciprocal radiation based on magnetized plasma in the Voigt configuration. The structure comprises a plasma layer biased by a magnetic field, interfaced with a dielectric substrate and air. Excited TM0 surface waves propagate along the dielectric-air interface transition to radiative leaky-wave modes. Experimentally observed nonreciprocity includes an 8 dB gain asymmetry between transmission and reception that is reversible via magnetic field polarity inversion. Multiple frequency bands exhibit three distinct radiation mechanisms with nonreciprocal fast-wave leakage and a truly unidirectional leaky mode. These are predicted by the derived dispersion relation. Radiation patterns under magnetized plasma and unmagnetized plasma conditions confirm nonreciprocal transmission exclusively in magnetized states. Simulations closely match measurements and validate tunable operational frequency and nonreciprocal response through plasma density and magnetic bias control. This platform enables passive nonreciprocity without time modulation and offers applications in communications, radar/sensing systems, radar cross-section reduction, and RF front-end optimization.