A magnetron when operated under pi (π) mode gives maximum output power and desired frequency. Since the magnetron has eight coupled cavity resonators, several different modes of oscillation is possible. The oscillating frequency corresponding to the different modes are not the same. Some are quite close to one another, so that a π-mode oscillation which is normal for magnetron becomes (3/4)π mode oscillation. This is called as mode jumping.

In order to avoid mode jumping strapping technique is used. Strapping consists of two rings of heavy gauge wire connecting alternate anode poles. These are the poles that should be in phase with each other for π-mode. Phase other than π is prevented by strapping.

Rising Sun Structure: When working at reduced wavelength and under large number of cavities strapping becomes difficult. Under this situation, mode separation is obtained by the use of rising sun resonator system in which the natural frequencies of adjacent resonator differ, but alternate resonators are alike. If the mode jump occurs, DC field used for biasing the magnetron will not support it.