Antenna Systems & Technology - Summer 2015 - (Page 4)

EDITOR'S CHOICE New Antennas Use Phase-Changing Material to Alter Shapes, Frequencies Two new antenna prototypes are the first to be developed using a special class of thin film material, which allows them to alter their shape using temperature and radiate at varying frequencies within the popular GHz range. A single reconfigurable antenna could replace two or more traditional antennas, including those in cell phones, WiFi and numerous military devices. The new antennas developed at the South Dakota School of Mines & Technology, in collaboration with Michigan State University, were documented in the IEEE Antennas and Wireless Propagation Letters in February. They are made by integrating vanadium dioxide thin films, a type of "phase-change" material, meaning it is an insulator at room temperature and becomes metal when heated above 68°C. The heating-cooling cycle is repeatable and the phase-change is reversible. Principal investigator and renowned expert Dimitris Anagnostou, Ph.D., of the South Dakota School of Mines & Technology, led the research with his graduate student Tarron Teeslink, collaborating with Nelson Sepulveda, Ph.D., and his student David Torres, from Michigan State University. Volume 19 / Issue 2 Editor & Publisher David Webster Director of Content Nick Depperschmidt Senior Editor Shannon Given Associate Editor Heather Williams News Editors Sue Hannebrink, Scott Webster William Massey Advertising Sales and Marketing William Massey, Advertising Sales Manager Dimitris Anagnostou of the South Dakota School of Mines & Technology holds a vanadium dioxide reconfigurable bowtie antenna prototype that can change its frequency when heated. Vanadium dioxide has the advantage of being an extremely linear low-loss material, so it can be used over wide frequency bands. The proofof-concept antenna (as well as other prototypes) are the result of a complementary collaboration with Nelson Sepulveda's group at Michigan State University that focuses on smart materials. Anagnostou, associate professor in the Department of Electrical & Computer Engineering, has been working on reconfigurable and tunable antennas for the past 15 years. Common methods to date have resulted in non-linearities, high losses, expensive fabrication equipment and often complicated biasing mechanisms. His exploration of vanadium dioxide has shown the material can be used in linear devices, has minimal losses and can be activated using a variety of heat transfer methods. Linear devices for radio-frequency communications applications involve usually passive components such as antennas and (microwave) filters, as well as resistors, capacitors and inductors. Often antennas are tuned or reconfigured using non-linear components such as diodes, but these distort the electrical signals, especially over a wide range of frequencies. Vanadium dioxide is a linear material, meaning it affects all radio frequencies by the same amount causing no distortion, and is therefore suitable for narrowband and wideband tuning. 4 Antenna Systems & Technology Summer 2015 Administration Marsha Grillo, Director Support Services/Circulation Marc Vang, Director Ross Webster, Data Entry Webmaster CJ Brewer Production Julie Hammond Carmen Abraham ANTENNA SYSTEMS & TECHNOLOGY (ISSN #1092-2553) is a publication of Webcom Communications Corp. Subscriptions for one year (bi-annually) are free to qualified recipients in the U.S., $44 for non qualified U.S. and $60 outside the U.S. Single copies are $20 each plus shipping. Back issues are available. Payment must be made in US funds in order to process the order. Direct all subscription inquiries, orders and address changes to Fulfillment Services. © Copyright 2015 Webcom Communications Corp. Material in this publication may not be reproduced in any form without written permission. Requests for permission should be directed to the customer service manager. Reprints: For reprint requests contact Webcom Communications at 720-528-3770. Webcom Communications Corp. 7355 E. Orchard Road, Ste. 100 Greenwood Village, CO 80111 Phone 720-528-3770 Fax 720-528-3771 www.AntennasOnline.com www.AntennasOnline.com http://www.AntennasOnline.com http://www.AntennasOnline.com

Table of Contents for the Digital Edition of Antenna Systems & Technology - Summer 2015

Editor’s Choice
The Future of DAS - In-Building and Dynamic Capacity
Impedance Matching is No Match for Aperture Tuning
All Band VSAT Antenna Radomes: A New Perspective
Antennas
Components/Subsystems
Software / System Design
Test & Measurement
Industry News
Marketplace
DAS and Small Cells, Revisited

Antenna Systems & Technology - Summer 2015