Active Standing Wave Antenna Oscillator at Exceptional Point with Discrete Nonlinear Gain

A periodically loaded waveguide made of discrete nonlinear gain and radiating elements makes an oscillator array that tends to operate at an exceptional point of degeneracy (EPD) after reaching saturation. The coalescing eigenvalues at the EPD are the modal wavenumbers of the infinitely long array. Relying on the concept of EPDs, we show that there is a great synchronization regime with a stable oscillation frequency, leading to a notable increase in distributed radiating power for longer array lengths. The system consistently maintains a steady-state degenerate mode of oscillation, even when the small-signal nonlinear gain distribution is not uniform or perturbed. Importantly, the oscillation frequency does not depend on the array length, contrary to what happens in conventional one-dimensional cavity resonances. Furthermore, our demonstration highlights that nonuniform gain across the structure yields consistent oscillation frequency and uniform power radiation from the arrays. These findings hold significant implications for high-power radiating arrays incorporating distributed active elements.