TechBlog

Antennas serve as transducers between electromagnetic waves traveling in free space and guided electromagnetic signals in circuits. As such, they play a critical role in the performance of wireless communication systems. With the proliferation of mobile wireless services that deliver voice and/or data in smaller and smaller devices, the task to design an antenna for a portable unit that meets not only operational requirements but also aesthetic and packaging restrictions is becoming more and more challenging. As result, engineers rely on a combination of theory, simulation, and experimental investigation to arrive at a design that meets all the demands of a particular application.

Basic Antenna Parameters

The basic parameters of antenna are impedence, mismatch and ohmic efficiency, radiation pattern and polarization, directivity, gain and equivalent isotropically radiated power, and effective height and aperture. In addition, celebrated Friis equation is and equations for the signal to noise ratio (SNR) of an antenna and source-field relationships are also important.For a more detailed treatment of the material pointed out here, the reader is referred to “A HANDBOOK OF ANTENNA IN WIRELESS COMMUNICATION” OF CRC Press by Lal Chand Godara.

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Ortech has a wide range of Technical Ceramics Materials to offer. Each one with its own unique characteristics designed to meet the requirements of many diverse applications. Some of the more widely used materials are described below.

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Carbon nanotubes have a sound future in the electronics industry, say researchers who built the world’s first all-nanotube transistor radios to prove it.

The nanotube radios, in which nanotube devices provide all of the active functionality in the devices, represent “important first steps toward the practical implementation of carbon-nanotube materials into high-speed analog electronics and other related applications,” said John Rogers, a Founder Professor of Materials Science and Engineering at the University of Illinois.

Rogers is a corresponding author of a paper that describes the design, fabrication and performance of the nanotube-transistor radios, which were achieved in a close collaboration with radio frequency electronics engineers at Northrop Grumman Electronics Systems in Linthicum, Md.

The paper has been accepted for publication in the Proceedings of the National Academy of Sciences, and is to be published in PNAS Online Early Edition next week.

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Berkeley, CA — As structures made of metal get smaller — as their dimensions approach the micrometer scale (millionths of a meter) or less — they get stronger. Scientists discovered this phenomenon 50 years ago while measuring the strength of tin “whiskers” a few micrometers in diameter and a few millimeters in length. Many theories have been proposed to explain why smaller is stronger, but only recently has it become possible to see and record what’s actually happening in tiny structures under stress.Andrew Minor, of the Materials Sciences Division in the Department of Energy’s Lawrence Berkeley National Laboratory, with colleagues from Hysitron Incorporated and the General Motors Research and Development Center, used the In Situ Microscope at the National Center for Electron Microscopy (NCEM) to record what happens when pillars of nickel with diameters between 150 and 400 nanometers (billionths of a meter) are compressed under a flat punch made of diamond. The transmission electron microscope is equipped so that samples can be stressed, measured, and videotaped while being observed under the electron beam.

“What controls the deformation of a metal object is the way that defects, called dislocations, move along planes in its crystal structure,” Minor says. “The result of dislocation slip is plastic deformation. For example, bending a paper clip causes its trillions of dislocations per square centimeter to tangle up and multiply as they run into one another and slide along numerous slip planes.”

In general, mechanical deformation tends to increase the number of dislocations in a material. But for small-scale structures, with a much greater proportion of surface area to volume, the process can be very different. The videotaped images from the electron microscope helped the researchers understand why nanoscale nickel pillars are so strong by allowing them to observe changes in the microstructure of the pillars during deformation — including a never-before-seen process the researchers dubbed “mechanical annealing.” (In bulk materials, annealing, a treatment that reduces the density of defects, is usually accomplished by heating.)

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