Passive Inter-modulation

The advent of wireless with its tightly grouped, high power, high frequency signals and the associated high sensitivity receivers has created many unanticipated PIM (Passive Intermodulation) problems. PIM is caused by improper design of the passive components that transport the high power wireless signal from the transmitter to the airwaves. PIM becomes a significant problem when this transmission line is shared by the receive signal, either directly or coupled in some way, since the PIM products can fall in the receive band and interfere with the receive performance. This brief overview describes a few of the problems and solutions encountered by Microlab/FXR in its efforts to supply PIM-free wireless components.