James Lyke

Design, fabrication, and measurements of an RF-MEMS-based self-similar reconfigurable antenna

Reconfigurability in an antenna system is a desired characteristic that has been the focus of much research in recent years. In this work, ohmic contact cantilever RF-MEMS switches are integrated with self-similar planar antennas to provide a reconfigurable antenna system that radiates similar patterns over a wide range of frequencies. The different issues encountered during the integration of the MEMS switches and the overall system design procedure are described herein. The final model radiates at three widely separated frequencies with very similar radiation patterns. The proposed concept can be extended to reconfigurable linear antenna arrays or to more complex antenna structures with large improvements in antenna performance.

Applications of neural networks in wireless communications

In recent years, the art of using neural networks (NNs) for wireless-communication engineering has been gaining momentum. Although it has been used for a variety of purposes and in different ways, the basic purpose of applying neural networks is to change from the lengthy analysis and design cycles required to develop high-performance systems to very short product-development times. This article overviews the current state of research in this area. Different applications of neural-network techniques for wireless communication front ends are briefly reviewed, stressing the purpose and the way neural networks have been implemented, followed by a description of future avenues of research in this field.

Neurocomputational analysis of a multiband reconfigurable planar antenna

Procedures using neural networks are developed for characterizing multiband reconfigurable antennas. A multilayer perceptron (MLP) is used to locate the operational frequency bands of the antenna at different reconfigured conditions. Another self-organizing map (SOM) neural network accomplishes the task of locating the switches to be turned ON for a desired frequency response. The developed formulation is tested on a laboratory prototype antenna.

FPGA-Controlled Switch-Reconfigured Antenna

In this letter, p-i-n diodes are used as switches to connect and disconnect four patch sections to a midsection of a planar antenna. The antenna system is connected to the field programmable gate array (FPGA) board controlling the activation of these switches. The antenna with the incorporated diodes is designed, installed, and measured. The methodology for using an FPGA to optimally control and produce the desired antenna frequency operation is presented and analyzed. The analogy between the measured and simulated results is found to be satisfactory. The proposed control methodology can be used with various antenna designs to obtain different possible states in an easy, fast, and low-cost manner.

Silicon-etched re-configurable self-similar antenna with RF-MEMS switches

Self-similar antennas have been well known for their multiband characteristics. The use of series ohmic contact cantilever RF MEMS switches in coordination with a simple self-similar antenna is exploited. The compatibility of the designs and the fractal nature of the antenna can lead to large increases in antenna performance, since not only a wider selection of frequencies, but also several different radiation patterns can be radiated with a single antenna. In this paper, the design and the compatibility of the switches and simulated results are presented.

A frequency reconfigurable antenna design using neural networks

In this work, design aspects of a frequency reconfigurable antenna are handled using neural networks. The job of the neural network is to determine the switches that are to be made ON for the structure to resonate at specific bands. This task is handled as a classification type of problem and is accomplished by a self-organizing map neural network (SOM NN).

An Introduction to Reconfigurable Systems

Reconfigurability can be thought of as software-defined functionality, where flexibility is controlled predominately through the specification of bit patterns. Reconfigurable systems can be as simple as a single switch, or as abstract and powerful as programmable matter. This paper considers the generalization of reconfigurable systems as an important evolving discipline, bolstered by real-world archetypes such as field programmable gate arrays and software-definable radio (platform and application, respectively). It considers what reconfigurable systems actually are, their motivation, their taxonomy, the fundamental mechanisms and architectural considerations underlying them, designing them and using them in applications. With well-known real-world instances, such as the field programmable gate array, the paper attempts to motivate an understanding of the many possible directions and implications of a new class of system which is fundamentally based on the ability to change.

A dynamically reconfigurable computing model for video processing applications

We introduce an idealized dynamically reconfigurable computing model that is suitable for applications in video processing applications. Dynamically reconfigurable computing is characterized by a dynamic data path which has been made possible with the partial reconfiguration feature available in modern FPGA devices. Dynamically reconfigurable computing design leads to a multi-objective optimization model with constraints on power, performance and resources. We provide a review of recent reconfigurable computing applications reported by different groups and propose a new model for dynamically reconfigurable video processing applications. We provide model measurements for reconfiguration time overhead, static and reconfiguration power consumption.

Improved multiband performance with self-similar fractal antennas

Fractal antennas have the characteristic of radiating in multiple frequencies, usually in a logarithmic pattern, through the property of self-similarity that fractal shapes possess. By connecting fractal shaped antennas, wideband coverage can be achieved. The analysis, design principles and several examples are shown to demonstrate this concept.

Analyzing the Complexity and Reliability of Switch-Frequency-Reconfigurable Antennas Using Graph Models

This paper addresses the functional reliability and the complexity of reconfigurable antennas using graph models. The correlation between complexity and reliability for any given reconfigurable antenna is defined. Two methods are proposed to reduce failures and improve the reliability of reconfigurable antennas. The failures are caused by the reconfiguration technique or by the surrounding environment. These failure reduction methods proposed are tested and examples are given which verify these methods.