Applied Frequency‐Domain Electromagnetics

Paknys, R.

doi:10.1002/9781119127444

Cited by 54 publications

(26 citation statements)

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“…In order to deconvolve components of the uniaxial permittivity tensor (uPT) from the intensity measurement, we first develop a forward model that relates the uPT to measured intensities. Our model integrates vector wave equation (71,72) and partially coherent scalar imaging model (73-75) assuming Born approximation (3), i.e., single-scattering. This partially coherent, vectorial model linearly links the measured Stokes parameters with the 3D distribution of the permittivity tensor of a weakly scattering specimen through transfer functions that describe the optical path.…”

Section: A: Forward Modelmentioning

confidence: 99%

“…This permittivity determines the amount of average and differential optical phase shift and the characteristic axes responding to different input polarization modes, which corresponds to specimens' density and anisotropy information. In the following subsections, we explain how the information of this permittivity is coupled to measurable quantities through vector wave equation (71,72) and partially coherent imaging model (73)(74)(75).…”

Section: Supplementary Note 1: Derivation Of the Forward Modelmentioning

confidence: 99%

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uPTI: uniaxial permittivity tensor imaging of intrinsic density and anisotropy

Yeh

Ivanov

Guo

et al. 2020

Preprint

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Architecture of biological systems is important for their homeostatic functions and is predictive of pathology. Volumetric imaging of intrinsic density, anisotropy, and 3D orientation of cell and tissue components is informative, but still challenging. These physical properties can be described succinctly by the volumetric distribution of the specimen’s permittivity tensor (PT). We report uniaxial permittivity tensor imaging (uPTI), a novel approach for label-free volumetric imaging with diffraction-limited resolution. uPTI combines the oblique illumination and the polarization imaging with high numerical apertures to encode the specimen’s permittivity tensor into intensity modulations, which are decoded with a novel vector diffraction model and a multi-channel convex optimization. The uPTI volumes of polystyrene beads and laser-fabricated anisotropic glass targets show that 3D uPT measurements are quantitative, with diffraction-limited spatial resolution of 0.23 × 0.23 × 0.8 μm3. Automated 2D and 3D imaging of a mouse brain section reveals anatomy at multiple scales (cm – 250 nm) and demonstrates that uPTI enables analysis of the density, anisotropy, and orientation of axon bundles and single axons. We multiplex uPTI with fluorescence de-convolution microscopy to enable correlative analysis of physical and molecular architecture of iPSC-derived cardiomyocytes. uPTI can be added to an existing widefield microscope as a low cost module. We share our implementation of the forward model and optimization algorithms via open source repository. Collectively, the reported advances in optical design, image formation, reconstruction algorithms, and biological interpretation open multiple avenues to study architecture of organelles, cells and tissue sections, including human cells and tissues that are challenging to label.

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Section: A: Forward Modelmentioning

confidence: 99%

Section: Supplementary Note 1: Derivation Of the Forward Modelmentioning

confidence: 99%

uPTI: uniaxial permittivity tensor imaging of intrinsic density and anisotropy

Yeh

Ivanov

Guo

et al. 2020

Preprint

View full text Add to dashboard Cite

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“…where D h L, ϕ, ϕ , n is the UTD building edge diffraction coefficient for vertical polarization [33] form of a lossy diffraction coefficient has been derived in [34] and W is the reflection coefficient [13]. The parameters τ 1 and τ 2 are the time delays of the direct and the building wall reflecteddiffracted rays.…”

Section: E Calculation Of Baseband Impulse Response For a Ray Contrimentioning

confidence: 99%

“…The angles of ϕ 1 , ϕ 1 , ϕ 2 , ϕ 2 are indicated in the Fig. 3 and also n 1 and n 2 is the wedge index of first and second diffraction edges of B 1 [33]. The building permittivity ε r is set to 5 for the selected frequency [13].…”

Section: E Calculation Of Baseband Impulse Response For a Ray Contrimentioning

confidence: 99%

New Modified Urban Canyon Models for Satellite Signal Propagation Prediction

Hadidianmoghadam

Kouki

2019

IEEE Access

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The effects of high-rise buildings on satellite propagation in the vicinity of urban canyons are investigated. A comparison between a conventional canyon model and the two modified canyon models, which take into account the presence of high-rise buildings, is presented for both narrow-band and wideband signal cases. The narrow band is developed using ray tracing (RT) and includes the direct wave, the specular reflection from building walls and ground, and the diffracted waves. In addition, multiple shadow boundaries are defined and used to carry out the uniform theory of diffraction calculations. The incident shadow boundary is the dominant boundary and is used to determine the line-of-sight region for all cases, while wall and ground reflection shadow boundaries are used to obtain higher precision due to multiple reflections. The wideband model is developed by applying a channel transfer function to the data obtained from the RT method. The proposed models are used to predict the received signal in a realistic urban environment from satellites. The models are applicable to any satellite link application, such as global navigation satellite systems, low Earth-orbiting, and high-altitude platform systems, and the results are obtained for a satellite transmitting two linearly polarized signals at a frequency of 1.625 GHz. It is found that the presence of highrise buildings next to a street canyon can significantly alter the visibility of satellites, which, in turn, lead to an increase in path loss. Consequently, ignoring high-rise buildings in the proximity of a street canyon can lead to a path loss difference of as much as 30 dB. INDEX TERMS Street canyon, conventional canyon model (CCM), non-line of sight (NLOS), ray tracing (RT), uniform theory of diffraction (UTD).

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“…16 of[16]) to give the fields at a rectangular grid of 200 royalsocietypublishing.org/journal/rsos R. Soc. Open Sci.…”

mentioning

confidence: 99%

Experimental evaluation of spectral efficiency from a circular array antenna producing a Laguerre–Gauss mode

2020

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We present the four-dimensional volumetric electromagnetic field measurements ( x , y , z and frequency) of the complex radiated field produced by an 8-element circular antenna array. The array is designed to produce a Laguerre–Gauss (LG) mode l = +1 over the frequency range of 9–10 GHz. We evaluate our findings in terms of far-field LG mode purity and spectral efficiency in terms of the quadrature amplitude modulation (QAM) modulation scheme that can be supported. The application of LG modes in radio systems is as a means of multiplexing several data streams onto the same frequency, polarization and time slot, thus making a highly spectrally efficient transmission system or enhancing radar systems by means of exploiting mode behaviour as an additional degree of freedom. Our results show that for the circular antenna array, we find that mode purity is sufficient to support binary phase shift keying or quadrature phase shift keying modulation over a 0.3 GHz bandwidth, which corresponds to a spectral efficiency of 1.5 b s −1 Hz −1 per mode. Closer to the antennas' design frequency, 256QAM modulation may be supported over a 0.05 GHz band, and which corresponds to a spectral efficiency of 11 b s −1 Hz −1 per mode. We anticipate the practical insights provided in this paper contribute to the successful design of such systems.

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Applied Frequency‐Domain Electromagnetics

Cited by 54 publications

References 0 publications

uPTI: uniaxial permittivity tensor imaging of intrinsic density and anisotropy

uPTI: uniaxial permittivity tensor imaging of intrinsic density and anisotropy

New Modified Urban Canyon Models for Satellite Signal Propagation Prediction

Experimental evaluation of spectral efficiency from a circular array antenna producing a Laguerre–Gauss mode

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