A resonant cavity with a bowtie shape supports an electromagnetic field used to deflect the trajectory of an electron beam passing through the cavity. The short transit time of the beam across the gap maintains the cavity fields at near-optimal phase, improving interaction efficiency even for relatively low-energy beams. High interaction impedance ensures good drive-power-to-deflection conversion efficiency. The uniform field achieved across the gap enforces uniform deflection across the beam profile to maintain beam quality. Multiple bowtie cavities can be arranged to allow arbitrary two-dimensional deflections.