This thesis deals with the jointly processing of radar signals stemming from independent sensors observing the same scattering scenario at different frequency bands. The suitability of a simple point-scatterer model to describe complex scattering mechanisms is verified over wide bandwidths. The minimum error in the estimation of multiband radar signal parameters is obtained using the Cramer-Rao theorem. The resolution problem (separation of targets) is treated as a test of the hypotheses of one or two closely-spaced scatterers present in the radar signal. Accuracy and resolution limits for multiband data sets are obtained for different distances between the frequency bands. To process multiband radar signals, high-resolution spectral estimators are adapted to cope with the multiband case. While the accuracy improves with increasing band distance, no general improvement of the resolution performance is observed. Additionally, an approach to estimate the distance between the frequency bands is developed. Monte Carlo analyses confirm the fundamental behavior of the resolution and accuracy dependence on the band gap.