Download or read book Conception et optimisation d une base compacte millim trique de mesures d antennes written by Yannick Poupin and published by . This book was released on 2002 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les mesures d'antennes imposent de propager une onde quasi-plane entre l'émetteur et le récepteur. Les bases compactes assurent cette condition de champ lointain sur des distances relativement réduites, générant une onde quasi-plane en champ proche. Ce mémoire présente toutes les étapes de conception d'une base compacte de mesure d'antennes (BCMA) fonctionnant de 10GHz à 50GHz, basée sur un réflecteur parabolique à bords enroulés. L'étude traite de la caractérisation par FDTD d'un modèle réduit de réflecteur. Les champs diffractés émis par la discontinuité de la surface à l'ordre 4, l'état de surface (rugosité), le rayon de courbure minimum de l'enroulement, sont quantifiés. Les performances sont optimales lorsque les champs parasites sont minimisés; le comportement du réflecteur peut alors être évalué par une méthode rapide en lancer de rayon (optique géométrique). Les conclusions sont alors appliquées au modèle réel, qui ne peut être étudié par FDTD: espace mémoire et temps de calcul prohibitifs. Nous présentons le design d'une chambre anéchoïque de BCMA : répartition d'absorbants pyramidaux et dièdres, selon l'incidence du rayonnement. Enfin, nous établissons une première étape de validation de la base en bande K et KA. Des cornets standards sont mesurés en rayonnement et gain, en parallèle dans les BCMA du CREAPE et du CNES.

Download or read book Satellite Situation Report written by Goddard Space Flight Center. Office of Public Affairs and published by . This book was released on 1977 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Historical Dictionary of Iran written by John Henry Lorentz and published by Historical Dictionaries of Asia, Oceania, and the Middle East. This book was released on 2007 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an overview of specific events, movements, people, political and social groups, places, trends, and chronology. Allows for considerable exploration of a number of historical and contemporary topics and issues. The modern period, defined as 1800-present, is covered extensively.

Download or read book Space Debris written by Heiner Klinkrad and published by Springer Science & Business Media. This book was released on 2006-09-01 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: The future evolution of the debris environment will be forecast on the basis of traffic models and possible hazard mitigation practices. The text shows how large trackable objects will have re-entry pinpointed and predictions made on related risk assessment for possible ground impact. Models will also be described for meteoroids which are also a prevailing risk.

Download or read book Historical Dictionary of Pakistan written by Shahid Javed Burki and published by . This book was released on 1999 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pakistan is unlike most other countries in the emerging world. It is one of the two nations – the other being the state of Israel – founded on the basis of religion. Although it was created to provide a homeland for the Muslim community of British India, in its original form it was able to accommodate only about half of the people of Islamic faith who lived in the subcontinent. Pakistan’s birth in 1947 resulted in one of the largest movements of people in human history when some 14 million people left their homes, with 8 million Muslims leaving India for what is now Pakistan and 6 million Hindus and Sikhs moving in the opposite direction. This was the first large-scale incidence of ethnic cleansing the world was to witness. --

Download or read book Water Treatment Handbook written by and published by . This book was released on 2007 with total page 932 pages. Available in PDF, EPUB and Kindle. Book excerpt: