The use of software radio technology has spread to almost every commercial, consumer, government, industrial, and military platform across the entire radio frequency spectrum during the technology's 25-year lifespan. Innovations in data converter technology, DSP devices, system interconnects, processors, software, design tools, and packaging techniques have improved performance levels and reduced the size, weight, and power consumption of software radio systems. However, the rapid surge in software radio applications spawned ad hoc, proprietary interfaces between the elements in these systems.
To meet the constant consumer demand for higher bandwidth in their wireless devices, companies have developed ultra-wideband communications equipment and advanced wireless techniques, such as frequency-hopping spread spectrum transmission, in which radio signals are rapidly switched between frequencies. The same technique can also guard against eavesdropping. With those advances, however, comes a growing challenge for manufacturers of the high-performance printed circuit boards aimed at the wireless communications market. That challenge lies in controlling a phenomenon known as Passive Intermodulation.