Ballistic Missile Innovative Radar and RF Products

The use of nonlinear and chaotic dynamics in rf engineering is still in the research stage, but the payoff for successful applications could be great. We have developed and prototyped a new type of amplifier that uses a nonlinear operating point and hasremarkable power conversion efficiency, but is capable of the linear amplification of common waveforms. The focus of this SBIR is to use computer models and experiments to obtain larger effective bandwidths for wideband radar applications. Since Syncrodyneis already geared up to develop and prototype an 800 MHz HBT-based device, we will perform theoretical work towards a true distributed-element wideband amplifier design meeting the requirements in the solicitation. We stress that the idea of using anonlinear oscillator as an amplifier may sound unusual, but requirements for wideband military systems and 3rd generation commercial wireless applications are becoming so demanding that major changes in amplifier design approaches must be considered. Ourapproach is based on carefully controlled nonlinearity, so that we can achieve linear and stable transfer characteristics while maintaining the efficiency advantage of a nonlinear operating point. Broadband amplifiers tend to highly inefficient,especially if they used to amplify signals with large peak-to-average power ratios. Our approach has a direct market in the wireless personal communications area, and if successfully broadbanded, the market, both military and commmercial, would widenconsiderably. In personal wireless devices, for example, the efficiency of the rf power amplifiers for signals with large variations in the amplitude envelope remains extremely low; 20 percent power-added efficiency is not uncommon. (Standards adopted forthe next generation of cellular communications use signals with high peak-to-average power ratios. Such signals are necessary to increase bandwidth efficiency.) Because it is not possible now to change the standards, the only option available to achievecomparable battery life to voice-only handsets is to radically change implementation architectures. In the RF domain, this means that linear circuit approaches must be abandoned in favor of nonlinear designs. Strongly nonlinear RF architectures arepossible with amplifiers based on chaotic dynamics, but the system itself can have a linear transfer function, thus allowing for high power-conversion efficiency as well as low signal distortion for non-constant envelope signals.