Generation and Radiation of UWB-signals

Abstract

The most promising radiated UWB-signal is bipolar short one, like on sine cycle with time position modulation. The compromise between complexity, technology and compatibility is central frequency 2-5 GHz, which corresponds to short (<500 ps) pulse having 2-4 half periods at pulse repetition rate 10-100 MHz. Time position control should be down to 10 ps. Peak power reaches tens and hundreds Wtts even at low average powers. Randomly hoping period requires low, "previous periods memory", a new, poor known, requirement. The inherent for usual power semiconductor devices output low impedance cannot be effectively matched with higher impedance of an UWB antenna. The best technology is power compression by use of new semiconductor drift step recovery devices, including two types: Drift Step Recovery Transistors (DSRT), Drift Step Recovery Diodes (DSRD). The best antennas for UWB are arrays of TEM horns, where the low cut off frequency is limited by E-plane span. The most critical part of array is a power splitter. The best solution is an active array, when separate pulser, synchronized with others, feeds a horn. It may be stated that discussed technologyes are able to solve practically all current problems in UWB communication, positioning and radars.