Abstract: In order to improve the tracking accuracy of monopulse radars, and decrease sum/difference channel amplitude phase inconsistency on angle measurement precision of the feature, this paper discusses the issues relating to correction imbalance between sum and difference channels in wideband monopulse radars. A wideband correction algorithm is presented. The calibration parameters are estimated by local test signals injection. And then, a bank of interpolation filter is constructed to correct the frequency dependent imbalance errors. Simulation results are also given to validate the improvement features of this method.