Development and electromagnetic environment evaluation of ultra wideband device for the next generation mobile communication system

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Since the Federal Communications Commission authorized the unlicensed use of ultra-wideband (3.1-10.6 GHZ) in 2002, the ultra-wideband technologies have drawn great inter-est in short-range wireless communications such as locating and imaging of objects, in-vehicle sensing, monitoring of highways and other civil infrastructure, and so on. In order to realize such UWB wire-less communication systems, the ultra-wideband bandpass filter is one of the key passive components. We succeeded in the achievement of the ultra-wideband bandpass filter without electromagnetic inter-ference in order to integrate them with other components as a compact system. These methods include microstrip structures, parallel coupled line, step impedance resonator, short-circuited stub by via holes, etc. In order to complete the UWB-filter design, it is essential to know not only the input/output fre-quency characteristics with the network analyzer but also the electromagnetic field distribution and cur-rent distribution of center conductor to understand the ultra-wideband filter design, optimization, and operation principle for the microstrip planar structures. For measurement of all EM near field distribu-tions in UWB-BPFs fabricated on a microstrip structure, contactless field mapping technique using elec-tric and magnetic field probes was developed. The H-field can be measured using a small loop probe and an appropriate instrument such as network analyzer or spectrum analyzer and the E-field can be meas-ured using a coaxial type probe.