Ultra-Wideband RF Measurements

With more wireless connections being integrated into a wide range of products, many are looking for a wireless technology that can handle higher data rates approaching 1 Gb/s. All of the currently proposed solutions to meet that goal are focused on ultra-wideband (UWB) transmission systems.

The concept of UWB communication originated in the early days of radio. In the 1900s, the Marconi spark gap transmitter (the beginning of radio) communicated by spreading a signal over a very wide bandwidth. In the 1940's, Claude Shannon said the most efficient communication was "down in the noise". His "Mathematical Theory of Communication" explains that information carrying capacity may be increased by either widening the bandwidth or increasing the complexity of modulation. While most radio transmission is high power density with low bandwidth, an alternative would be low power density with wide bandwidth.

The communications world abandoned wideband in favor of narrowband or tuned radios in which, in the case of the U.S., the Federal Communications Commission governed spectrum allocation. The incidental radiated power limits were the motivation for various organizations to challenge the paradigm of narrowband communications, in an ongoing effort to squeeze capacity out of a highly regulated spectrum. Many companies argued that they should be allowed to intentionally transmit at the incidental radiated power limits over an ultra-wide bandwidth to take advantage of this capacity potential. This argument was the motivation for the FCC approval of UWB. In February, 2002, the FCC amended their Part 15 rules (concerning unlicensed radio device) to include the operation of UWB devices without a license.

UWB technology is expected to achieve data rates in excess of 1 Gb/s over short distances at low power. This makes UWB a practical alternative to high speed cabling. UWB has been demonstrated in a wide variety of electronics devices including digital audio-visual equipment, mobile phones, and PCs using wireless USB.