New-Tech Europe Magazine | Oct 2017 | Digital Edition

Combining MMIC Reflectionless Filters to Create Ultra-Wideband (UWB) Bandpass Filters Brandon Kaplan, Mini-Circuits, Matt Morgan, National Radio Astronomy Observatory, Tod Boyd, National Radio Astronomy Observatory

UWB: Background and Emerging Applications Ultra-Wideband (UWB) radio is defined as any RF technology utilizing a bandwidth of greater than ¼ the center frequency or a bandwidth greater than 500 MHz [1] [2]. While UWB has been a known technology since the end of the 19th century, restrictions on transmission to prevent interference with narrow- band, continuous wave signals have limited its applications to defense and relatively few specially licensed operators [1]. In 2002, the FCC opened the 3.1 to 10.6 GHz band for commercial applications of Ultra- Wideband technology, and since then UWB has become a focus of academic study and industry research for a promising variety of emerging applications. To prevent interference with neighboring

spectrum allocations like GPS at 1.6 GHz, the FCC has imposed specific rules for indoor and outdoor transmission of UWB signals, limiting transmissions in the permitted frequency range to power levels of -41 dBm/MHz or less. Research to date has explored many potentially valuable applications for UWB technology. For example, the wide bandwidth of UWB provides high channel capacity, allowing very high-speed data transfer at very low power. While the FCC power mask limits the range of UWB transmission to within roughly 10 meters, its high-speed, low-power characteristics have made UWB an attractive technology for certain short-range M2M communication applications like Wireless Personal Area Networking (WPAN) as well as low power sensor networks.[1]

UWB has also proven viable as a technology for new applications in detection, positioning and imaging. Modulation of UWB signals using ultra-short pulses in the order of nanoseconds enables precise location and ranging at the centimeter level [1] [6]. This capability has useful potential for military surveillance systems and other high-accuracy location and detection applications. The same high-resolution, high-penetration properties have also attracted research in the medical field, and a number of medical imaging applications have shown successful results. UWB systems have been used for non-invasive, precise detection of heart movements, and high-fidelity imaging using safe, non- ionizing radiation as an alternative to more harmful X-ray imaging.[3]

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