Estimation of the electromagnetic field radiated by a microwave circuit encapsulated in a rectangular cavity

A signal, propagating in an electronic circuit enclosed in a metal cavity, can excite the cavity's natural modes. In the context of RF amplifier reliability study against electromagnetic stress, a precise characterization of radiated emissions is imposed on us. This characterization is often achieved by measuring the near field of the circuit without enclosing it in a cavity (the top cover of the cavity is kept open), which does not always resemble the electromagnetic behavior when the same circuit is shielded within the cavity. In this work, we study the changes in the cartographies (electromagnetic fields mapping) of the electromagnetic field radiated under the influence of the metal cavity and we present a method to estimate the radiated field in the cavity from measurements made in the absence of the cavity. This method is validated for all frequencies except resonant frequencies.