ABSTRACTWith space and spectrum at a premium, antennas must be capable of operating well across a variety of frequencies and environments. This work presents a novel method of frequency and impedance reconfiguration through the actuation of a ferrofluid load with a permanent magnetic bias field, while still achieving up to 85% efficiency. Under a sufficiently strong bias field, the ferrofluid load behaves as a low-loss movable dielectric load, and the actuation method avoids the complexity associated with microfluidic pumps and DC bias networks. This work opens a new field of reconfiguration mechanisms for antennas through magnetic repositioning of low-loss ferrofluid loads.