Development of a broadband and squint-free Ku-band phased array antenna system for airborne satellite communications

Novel avionic communication systems are required for various purposes, for example to increase the flight safety and operational integrity as well as to enhance the quality of service to passengers on board. To serve these purposes, a key technology that is essential to be developed is an antenna system that can provide broadband connectivity within aircraft cabins at an affordable price. Currently, in the European Commission (EC) 7th Framework Programme SANDRA project (SANDRA, 2011), a development of such an antenna system is being carried out. The system is an electronically-steered phased-array antenna (PAA) with a low aerodynamic profile. The reception of digital video broadcasting by satellite (DVB-S) signal which is in the frequency range of 10.7-12.75 GHz (Ku-band) is being considered. In order to ensure the quality of service provided to the passengers, the developed antenna should be able to receive the entire DVB-S band at once while complying with the requirements of the DVB-S system (Morello & Mignone, 2006). These requirements, as will be explained later, dictate a broadband antenna system where the beam is squint-free, i.e. no variation of beam pointing direction for all the frequencies in the desired band. Additionally, to track the satellite, the seamless tunability of the beam pointing direction of this antenna is also required. In this work, a concept of optical beamforming (Riza & Thompson, 1997) is implemented to provide a squint-free beam over the entire Ku-band for all the desired pointing directions. The optical beamformer itself consists of continuously tunable optical delay lines that enable seamless tunability of the beam pointing direction

Storage by trapping and spatial staggering of multiple interacting solitons in Λ\Lambda-type media

In this paper we investigate the properties of self induced transparency (SIT) solitons, propagating in a $\Lambda$-type medium. It was found that the interaction between SIT solitons can lead to trapping with their phase preserved in the ground state coherence of the medium. These phases can be altered in a systematic way by the application of appropriate light fields, such as additional SIT solitons. Furthermore, multiple independent SIT solitons can be made to propagate as bi-solitons through their mutual interaction with a separate light field. Finally, we demonstrate that control of the SIT soliton phase can be used to implement an optical exclusive-or gate.Comment: 7 pages, 7 figure

Propagation and nonlinear scattering of ultrashort pulses - examples of modeling and applications

In this thesis we have presented theoretical and experimental investigations of\ud some fundamental properties and applications of nonlinear interaction between\ud ultrashort optical pulses and matter

NET ASSET VALUATION OF WHITING PETROLEUM’S ACQUISITION OF KODIAK OIL AND GAS

In July 2014, it was announced that Whiting Petroleum would acquire Kodiak Oil & Gas in an all-stock deal valued at $6 billion. Both companies are headquartered in Denver and operate primarily in the Bakken but in a deal of this size it is possible for executives to hold ulterior motives for mergers such as higher compensation and golden parachutes. Acceptable motivating factors for engaging in a merger include cost savings through synergies and economies of scale, increased market power, asset diversification, and price volatility. A net asset valuation was used to help determine if shareholders should vote in favor of the merger. Through increased market share and cost savings, the merger can be deemed a success for Whiting Petroleum