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- H. Alroughani, Jonathan L. T. Ethier, D. A. McNamara
- 2014 IEEE Antennas and Propagation Societyâ€¦
- 2014

Some computational aspects for the characteristic modes (CM) of dielectric objects are examined. Volume integral equation (VIE) formulations are reliable but computationally burdensome. The use of surface integral equation (SIE) formulations results in a lighter computational load but, we show here, obtrudes certain non-physical modes in addition to theâ€¦ (More)

- Jonathan L. T. Ethier, Derek A. McNamara
- IEEE Transactions on Antennas and Propagation
- 2014

An antenna shape synthesis method is proposed that allows shaping of the antenna geometry prior to specification of the feed location and type. This reduces the constraints placed on the optimization process and can lead to potentially new designs due to the increased degree of freedom afforded. An appropriate feedpoint is easily chosen after shapeâ€¦ (More)

- Jonathan L. T. Ethier, M. R. Chaharmir, Jafar Shaker, David C. M. Lee
- IEEE Antennas and Propagation Magazine
- 2012

Design techniques have been developed to commercialize reflectarray designs. The use of low-cost, lossy materials in the design of traditional reflectarrays has been shown to substantially reduce their performance, precluding any competitiveness with solid reflectors. A novel design technique is presented that mitigates these losses and allows forâ€¦ (More)

- Jonathan L. T. Ethier, D. A. McNamara
- IEEE Transactions on Magnetics
- 2009

If <i>N</i> ports are defined on the moment method model of a radiating structure, so-called characteristic port modes may be computed, using the moment method operator matrix, with respect to these ports. This results in <i>N</i> port excitation vectors (each of length <i>N</i>). Each vector excites a radiated field which is orthogonal to the fieldsâ€¦ (More)

- Jonathan L. T. Ethier, Derek A. McNamara
- 2010 IEEE International Conference on Wirelessâ€¦
- 2010

The theory of characteristic modes has been given in [1] for perfectly conducting objects. If we use a moment method formulation such as [2] to model a conducting structure, with N of the RWG expansion functions used, the EFIE is converted into a matrix equation [Z][J]=[V]. Column vector [J] contains the coefficients of the expansion functions for theâ€¦ (More)

- Jonathan L. T. Ethier, M. R. Chaharmir, Jafar Shaker
- IEEE Transactions on Antennas and Propagation
- 2012

A novel design approach is proposed for designing high performance reflectarrays using low-cost, lossy substrates. Using sub-wavelength coupled-resonant elements, in particular sub-wavelength loops, one can dramatically reduce losses in reflectarrays and not incur significant gain drop due to the use of the lossy, low-cost substrate. It is further shownâ€¦ (More)

- Jonathan L. T. Ethier, M. R. Chaharmir, Jafar Shaker
- 2011 IEEE International Symposium on Antennas andâ€¦
- 2011

A novel design approach is proposed for designing high performance reflectarrays using low-cost, lossy substrates. Using subwavelength elements, in particular subwavelength loops, one can dramatically reduce losses in reflectarrays and not incur significant gain drop due to the use of the lossy low cost substrate. It is further shown that the subwavelengthâ€¦ (More)

- Jonathan L. T. Ethier, D. A. McNamara
- IEEE Transactions on Magnetics
- 2009

An extended polarization-dependent generalized characteristic-mode theory for a radiating structure is given. We show how these modes can be computed and employed in the design of closely located multiple-input multiple-output multiantenna sets with low interantenna envelope correlation and good mean effective gain under realistic incoming powerâ€¦ (More)

- Jonathan L. T. Ethier, Derek A. McNamara
- 2010 14th International Symposium on Antennaâ€¦
- 2010

In recent years there has been a surge of interest in various disciplines within applied electromagnetics, including electrically small antennas, MIMO antennas, periodic structures and metamaterials. Though a multitude of interesting applications have arisen, there still remain numerous fundamental questions regarding these burgeoning areas of research. Weâ€¦ (More)

- Jonathan L. T. Ethier, Derek A. McNamara, Mohammad Reza Chaharmir, Jafar Shaker
- IEEE Transactions on Antennas and Propagation
- 2014

A new technique for synthesizing reflectarray antennas is presented. It utilizes fragmented elements in a manner that allows the elements of the reflectarray to be shaped-optimized so that a high degree of geometrical similarity is maintained between adjacent elements. The implication is that in a reflectarray of such elements each element will see anâ€¦ (More)