Effects of Mainlobe Jamming Cancellation on Angle Estimation in Subarray-Level Three-Channel Radar

High-power mainlobe jamming severely degrades the target-detection capabilities of array radars in complex electromagnetic environments. Although the difference-channel signal can be reused as an auxiliary reference to suppress the jamming component in the sum channel, the jamming component remains unmitigated in the measured difference channel of a three-channel radar without a dedicated difference–difference channel, thereby introducing additional angle-estimation errors. Addressing this, this study analyzes a subarray-level, three-channel monopulse array radar. Based on a one-dimensional uniform linear array and the sum–difference monopulse principle, we formulate a joint model for mainlobe jamming cancellation and angle estimation. We then evaluate how the jammer azimuth, jamming-to-signal ratio (JSR), number of jammers, and radar operating modes (search and tracking) affect the resulting angle error. Simulation results indicate that in search mode, cancellation restores local angle-estimation capabilities near the target direction. When the beam points near the jammer, the jammer approaches the null of the auxiliary difference beam, weakening the reference signal and causing pronounced nonmonotonic distortion in the angle-estimation curve. In tracking mode, the cancellation process yields smaller angle errors and increased stability. A two-element 4.03 GHz anechoic-chamber experiment completes the proof-of-principle validation for the core mechanism under the single-jammer search-mode scenario. These findings define the operational boundaries of using the difference-channel signal as an auxiliary reference for sum-channel jamming cancellation in three-channel radars, providing a theoretical foundation for angle-error compensation, receiving-channel design, and the refinement of interference cancellation techniques.