An evaluation method of electromagnetic shielding applied to microwave surface mount components

A major problem associated with surface mount components housed within a single large shield case is that a small amount of leakage energy may lead to parasitic coupling between different sub-circuits. A method to counteract such a coupling mechanism is described. First, the cavity modes are calculated from the physical dimensions of the shield case which are in turn limited by the dimensions of the mobile communications terminal. The effect of resonant cavity modes on the system is then described. Next, the design of a TEM-cell, for the evaluation of leakage energy from components mounted on a PCB surface is demonstrated. An evaluation method for use with this equipment is also proposed. Finally, the structure of a remodeled surface mount BPF is presented. The results of the BPF evaluation using the TEM-Cell are shown.