Nonreciprocal Time-Invariant Leaky Waves Enabled by Magnetized Plasma

This work demonstrates a topological nonreciprocal time-invariant leaky-wave antenna based on magnetized plasma in the Voigt configuration. The structure consists of a magnetized plasma layer (density 1e18 m⁻³, plasma frequency f_pe 9 GHz, collision frequency 1 GHz) interfaced with a finite thickness dielectric substrate and vacuum. The plasma is biased with a magnetic field of 80 mT (cyclotron frequency f_ce 2.24 GHz). TM₀ surface waves are launched along the dielectric-vacuum interface, transitioning into radiative leaky-wave modes. Experimental measurements demonstrate an 8 dB gain asymmetry between transmission and reception at 5 GHz, reversible by inverting the magnetic field polarity. Two frequency bands exhibit nonreciprocal radiation: 4–6 GHz and 6.5–9 GHz. These nonreciprocal leaky modes are predicted by the derived dispersion relation. Radiation patterns are measured in three configurations: magnetized plasma, unmagnetized plasma and absence of plasma. Reciprocal transmission is only in non-magnetized states observable. The system achieves a compensated gain of 10 dB after accounting for impedance mismatch at the maximum nonreciprocity. Computational simulations align closely with experimental data, validating the tunability of operational frequency and nonreciprocal response through adjustments to plasma density and magnetic bias. This platform enables passive nonreciprocity without time modulation with applications in full-duplex communications, radar and sensing.