Adaptive beamforming for microwave power transmission: Mitigating ionospheric scintillation in real time

Space-based microwave power transmission (MPT) from a solar power satellite to a terrestrial rectenna must contend with ionospheric irregularities that induce rapid amplitude and phase fluctuations, collectively known as scintillation. These disturbances degrade beam pointing accuracy and power transfer efficiency unless corrected on millisecond timescales. This paper presents a real-time adaptive beamforming framework that exploits a time-division duplex (TDD) pilot-aided channel estimation loop to continuously track and pre-compensate the ionospheric transfer function. The proposed architecture places a co-located pilot beacon at the rectenna; the satellite array receives the beacon, estimates the instantaneous complex scintillation gains for every element, and applies conjugate weights for the high-power downlink transmission within the same coherence interval. A decoupled Kalman-filter estimator is derived that models the stochastic evolution of ionospheric amplitude and phase in terms of the widely used Nakagami-*m* and Gaussian-scintillation paradigms. Numerical simulations at 5.8 GHz for a 1000-element phased array under strong scintillation ( S 4 = 0.8 ) demonstrate that the real-time adaptive scheme restores beam collection efficiency from a degraded 62% to over 94%, closely approaching the ideal diffraction-limited performance. The algorithm’s convergence, tracking error variance, and robustness to decorrelation time are quantified. A detailed hardware implementation analysis confirms that the required digital processing can be realized with current space-grade field-programmable gate arrays while respecting strict mass and power budgets. The results establish a viable path toward unconditionally stable, gigawatt-class MPT links for future space solar power stations.