Fundamental Efficiency Limits for Small Metallic Antennas

Fundamental limits of cylindrical antennas

Fundamental limits to extinction by metallic nanoparticles.

We show that there are shape-independent upper bounds to the extinction cross section per unit volume of dilute, randomly arranged nanoparticles, given only material permittivity. Underlying the limits are restrictive sum rules that constrain the distribution of quasistatic eigenvalues. Surprisingly, optimally designed spheroids, with only a single quasistatic degree of freedom, reach the upper...

Material for “ Fundamental Limits to Extinction by Metallic Nanoparticles ”

O. D. Miller, C. W. Hsu, 3 M. T. H. Reid, W. Qiu, B. G. DeLacy, J. D. Joannopoulos, M. Soljačić, and S. G. Johnson Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139 Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 Department of Physics, Harvard University, Cambridge, MA 02138 U.S. Army Edgewood Chemical Biological Center, Rese...

A Re-Examination of the Fundamental Limits on the Radiation Q of Electrically Small Antennas

AbstructAn exact method, which is more straightforward than those previously published, is derived for the calculation of the minimum radiation Q of a general antenna. This expression agrees with the previously published and widely cited approximate expression in the extreme lower limit of electrical size. However, for the upper end of the range of electrical size which is considered electrical...

Spectrum Sensing Via Reconfigurable Antennas: Fundamental Limits and Potential Gains

We propose a novel paradigm for spectrum sensing in cognitive radio networks that provides diversity and capacity benefits using a single antenna at the Secondary User (SU) receiver. The proposed scheme is based on a reconfigurable antenna: an antenna that is capable of altering its radiation characteristics by changing its geometric configuration. Each configuration is designated as an antenna...