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Pujara D.,Nirma University | Chakrabarty S.,Microwave Applications Group
IETE Journal of Research | Year: 2012

This paper presents the design and the experimental results of a dual-mode rectangular-matched feed. This type of feed cancels the unwanted high cross-polarization generated by the offset parabolic reflector antenna. In order to design this feed, higher order TE 11 mode has been added in correct amplitude and phase with the fundamental TE 01 mode in a rectangular structure. The proposed feed was then used as a primary feed to illuminate a linearly polarized offset parabolic reflector antenna. Through experimental results, it is verified that such a feed suppresses the undesired high cross-polarization introduced by the offset geometry of an offset reflector antenna. This kind of feed is very much suitable for monopulse tracking radar. Copyright © 2012 by the IETE. Source


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 1.13M | Year: 2010

The development of capabilities that allow significant removal or reduction of high Global Warming Potential (GWP) Green House Gases (GHG) in the environment is paramount to ensure human health and welfare. The objective of this effort is to develop critical components and technologies that will significantly reduce the need for GHG on the Airborne Warning and Control System (AWACS). In Phase I, Microwave Applications Group (MAG) determined that stress levels in two critical AWACS components – as currently configured – require the use of Sulphur Hexafluoride (SF6) – known to be a GHG. Therefore, the focus of Phase II is to develop replacement configurations of these components such that the use of SF6 is not required. That hardware will then be tested to ensure compliance with AWACS requirements. BENEFIT: Concepts leading to hardware configurations – which are proven in this effort to operate successfully without a GHG – will lead to development of replacement components in military and commercial applications. These applications include radar systems, linear accelerators, and other electrical and radio frequency system requirements.


Grant
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase I | Award Amount: 69.98K | Year: 2010

Phased array systems provide significantly greater data collection capabilities, expanded uses and higher reliability as they reduce or eliminate the need for rotating systems. The major hurdle for widespread usage of phased array systems has been the costs associated with not only developing these systems but also the recurring cost of fabrication and operation. This project investigates a disruptive technology by applying multi-ferroic materials to fabricate rf components for these applications. Although ferrites have historically been the choice for low insertion loss reciprocal and non-reciprocal devices, they are difficult to realize in small geometries and their switching time is excessive. Alternatively, active components are extremely costly and require tremendous power to account for adaptive gain concepts. This project develops an alternative that usurps the best of both constructions. In phase I this project will investigate test results of suitable multi-ferroic devices and evaluate the phase shifter and its required dc magnetic field bias to determine if it can achieve the specifications and evaluate manufacturing concepts to determine achievable methods of fabricating multi-ferroic based planar technology. The goal of phase II of this project is to deliver multiple multi-ferroic phase shifters whose performance parameters bridge the gap between these two technologies by providing the smaller size and faster switching of active components and the simpler control and lower insertion loss of ferrite in a miniaturized package.


Muller A.A.,Microwave Applications Group | Sanabria-Codesal E.,University of Valencia | Moldoveanu A.,University of Bucharest | Asavei V.,University of Bucharest | Faveimec J.F.,French National Center for Scientific Research
Asia-Pacific Microwave Conference Proceedings, APMC | Year: 2016

Tke paper presents in premiere a simple mapping property of the sum of the reflection and transmission parameters of reciprocal two port networks. It is proved that although the reflection and transmission parameter may have very complicated paths on the Smith chart, their sum will be always moving on the unit circle if the circuit is symmetric and lossless. Further once symmetrical losses at the ports occur their sum path will switch on a family of circles through one point. Using iuversive geometry we construct a new function which maps this family of circles in lines 011 the extended Smith chart. The proposed method for checking the symmetry uses just two parameters and avoids testing the phase of the corresponding input and output parameters. By means of the 3D Smith chart we propose in the end an alternative approach to visualize the parameters. © IEEE. Source


Muller A.A.,Microwave Applications Group | Favennec J.-F.,French National Center for Scientific Research | Sanabria-Codesal E.,Polytechnic University of Valencia
Asia-Pacific Microwave Conference Proceedings, APMC | Year: 2016

The paper introduces the concept of reflection matrices in the coupling matrix filter reconfiguration. It is shown that reflection matrices are complementary to rotation matrices a useful concept that can be used alternatively to rotation matrices in the similarity transformations that are applied in order to transform the coupling matrix to a suitable form. A cross-coupled filter example is given where both concepts are used. © IEEE. Source

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