Browsing by Subject "Free spaces"

Now showing 1 - 6 of 6

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Analysis of edge waves due to a point source in the presence of a PEC wedge
(IEEE, 2014) Ghassemiparvin, Behnam; Altıntaş, Ayhan
In this paper, we investigate the behavior of the field in the paraxial region of a perfectly conducting wedge and analyze the guiding effect of the wedge. It is observed that as the wedge angle increases, the guidance effect of the wedge decreases and the scattered field in the paraxial region is maximum for the half plane. In addition, interaction of the edge waves with a spherical impedance scatterer is investigated. It is found that for the backscattering case, as the impedance mismatch between the spherical boss and the free-space increases the scattered field due to the boss increases. However for the forward scattering case, impedance of the boss does not affect the scattered field significantly.
Unknown
Analysis of the longitudinal component of the electric field generated by flat and pixelated liquid crystal displays
(IEEE, 2016-07) Külçe, Onur; Onural, Levent
The longitudinal, z, component of the electric field is investigated for the pixelated and flat liquid crystal displays (LCDs) for monochromatic case. The pixelation process is assumed to occur in free space. The z component is computed in the Fourier domain by using Gauss's Law from the x and y components of the output electric field. The effect of the display parameters are discussed for a y polarized display in a phase only operation. It is found that, in the low frequency regions, the size of the region of the large magnitudes becomes smaller as the width of the active region increases. Moreover, the validity of the scalar theory for a single pixel is evaluated for varying pixel sizes. It is shown that, when the ratio of the width of the active region to wavelength is between 1.5 and 5, the error decays with oscillations between 43% and 5%. When that ratio is larger than 15, the error does not exceed 3%. © 2016 IEEE.
Open Access
Effect of spatial distribution of partial information on the accurate recovery of optical wave fields
(Optical Society of America, 2017) Oktem, F. S.; Özaktaş, Haldun M.
We consider the problem of recovering a signal from partial and redundant information distributed over two fractional Fourier domains. This corresponds to recovering a wave field from two planes perpendicular to the direction of propagation in a quadratic-phase multilens system. The distribution of the known information over the two planes has a significant effect on our ability to accurately recover the field. We observe that distributing the known samples more equally between the two planes, or increasing the distance between the planes in free space, generally makes the recovery more difficult. Spreading the known information uniformly over the planes, or acquiring additional samples to compensate for the redundant information, helps to improve the accuracy of the recovery. These results shed light onto redundancy and information relations among the given data for a broad class of systems of practical interest, and provide a deeper insight into the underlying mathematical problem.
Open Access
Near-field measurement of a planar meta-surface illuminated by dipole antennas
(IEEE, 2008-03) Saenz, E.; Güven, Kaan; Ederra, I.; Özbay, Ekmel; De Maagt, P.; Gonzalo, R.
In this paper, the uniform illumination of a meta-surface that is fed by a single dipole antenna or an array is experimentally investigated by means of near-field measurements. The results of the scanned field, when the dipoles are radiating in free space and when the meta-surface is placed atop them are presented. By means of this measurement, the coupling reduction between dipoles of an array due to the presence of the meta-surface is observed. ©2008 IEEE.
Open Access
Negative refraction and focusing by a left-handed material slab in free space
(IEEE, 2006) Aydın, Koray; Özbay, Ekmel
Negative refraction and focusing by a left-handed metamaterial (LHM) slab are experimentally verified. We measured refractive index of slab as -1.86. The flat lens behavior of LHM is demonstrated for two different point source distances. © 2006 Optical Society of America.
Open Access
Phase-space window and degrees of freedom of optical systems with multiple apertures
(Optical Society of America., 2013) Özaktaş, Haldun M.; Oktem, F. S.
We show how to explicitly determine the space-frequency window (phase-space window) for optical systems consisting of an arbitrary sequence of lenses and apertures separated by arbitrary lengths of free space. If the space-frequency support of a signal lies completely within this window, the signal passes without information loss. When it does not, the parts that lie within the window pass and the parts that lie outside of the window are blocked, a result that is valid to a good degree of approximation for many systems of practical interest. Also, the maximum number of degrees of freedom that can pass through the system is given by the area of its space-frequency window. These intuitive results provide insight and guidance into the behavior and design of systems involving multiple apertures and can help minimize information loss.