E.V. Jull

Bio: E.V. Jull is an academic researcher from University of British Columbia. The author has contributed to research in topics: Diffraction & Uniform theory of diffraction. The author has an hindex of 14, co-authored 48 publications receiving 597 citations.

Aperture Antennas and Diffraction Theory

Abstract: Chapter 1: Introduction Chapter 2: Plane waves from apertures Chapter 3: Fourier transform representation of aperture patterns Chapter 4: Near-field radiation patterns Chapter 5: Aperture gain Chapter 6: Applications of aperture theory to antennas Chapter 7: Diffraction by conductors with sharp edges Chapter 8: Geometrical theory of diffraction by edges Chapter 9: Applications of geometrical diffraction theory to antennas Appendixes

Beam diffraction by planar and parabolic reflectors

Abstract: In the complex source point technique, an omnidirectional source diffraction solution becomes that for a directive beam when the coordinates of the source position are given appropriate complex values. This is applied to include feed directivity in reflector edge diffraction. Solutions and numerical examples for planar strip and parabolic cylinder reflectors are given, including an offset parabolic reflector. The main beams of parabolic reflectors are calculated by aperture integration and the edge diffracted fields by uniform diffraction theory. In both cases, a complex source point feed in the near or far field of the reflector may be used in the pattern calculation, with improvements in accuracy in the lateral and spillover pattern lobes. >

Gratings that diffract all incident energy

Abstract: Perfect blazing of reflection gratings to the n = −1 spectral order for both TE and TM polarizations simultaneously, as reported recently, is shown to be possible with rectangular grooves in 19.5° < θi < 59.4°, where θi is the angle of incidence from the surface normal. Design dimensions are verified experimentally at 35 GHz.

Two-dimensional beam diffraction by a half-plane and wide slit

Abstract: The far field of a two-dimensional beam resulting from an electric line source at a complex position is described, its half-power beamwidth determined, and its validity as an antenna beam indicated. Farfield diffraction by a half-plane is then determined from an exact uniform solution for an isotropic line source by making the source position complex. The same basic solution and technique are used for beam diffraction by a wide slit, with first-order interaction between the slit edges included. Numerical results for normal incidence illustrate the evolution of the diffraction patterns from those for an omnidirectional source to those for a highly directive beam. Results for plane wave incidence by a slit also come out of this solution. The remarkable simplicity and convenience of this method relative to alternative asymptotic procedures is discussed.

Errors in the predicted gain of pyramidal horns

Abstract: The concepts of the geometrical theory of diffraction are used to derive the on-axis gain of two-dimensional E plane sectoral horns. Geometrical optics and single (noninteraction) diffraction by the aperture edges yield essentially the Kirchhoff result-a monotonic gain versus wavelength curve. Reflection of diffracted fields from the horn interior and double diffraction at the aperture add an oscillation to this curve which is not significantly altered by further diffraction for moderate to large horns. Including these results approximately in Schelkunoff's equation for the pyramidal horn explains the gain variations observed in microwave gain standards and provides an error estimate in their predicted gain.

Rigorous coupled-wave analysis of metallic surface-relief gratings

Abstract: A rigorous coupled-wave analysis for metallic surface-relief gratings is presented. This approach allows an arbitrary complex permittivity to be used for the material and thus avoids the infinite conductivity (perfect-conductor) approximation. Both TE and TM polarizations and arbitrary angles of incidence are treated. Diffraction characteristics for rectangular-groove gold gratings with equal groove and ridge widths are presented for free-space wavelengths of 0.5, 1.0 and 10.0 μm for all diffracted orders as a function of period, groove depth, polarization, and angle of incidence. Results include the following: (1) TM-polarization diffraction characteristics vary more rapidly than do those for TE polarization, (2) 95% first-order diffraction efficiency occurs for TM polarization at 10.0 μm, (3) 50% absorption of incident power occurs at 0.5 μm, and (5) the perfect-conductor approximation is not valid for TM polarization at any of the wavelengths and is not valid for TE polarization at 0.5 μm.

Effects of antenna directivity and polarization on indoor multipath propagation characteristics at 60 GHz

Abstract: In millimeter-wave indoor communications systems, the radiation patterns and polarizations of the antennas at base stations and remote terminals have a significant influence on channel characteristics. The work reported in this paper investigated the effects of the radiation patterns of the antennas at remote terminals on multipath propagation characteristics. These effects were investigated by indoor propagation measurements at 60 GHz conducted in a modern office room and by ray-tracing simulations based on geometrical optics. Multipath channel characteristics are compared in terms of impulse responses and their root-mean-square (rms) delay spreads for an omnidirectional antenna and for three directive antennas with different beam widths. From the results of measurements and ray-tracing simulations, the use of a directive antenna at the remote terminal is demonstrated to be an effective method of reducing the effects of multipath propagation. Further reduction in the multipath effects is found to be achieved by the use of circular polarization instead of linear polarization with the directive antennas.

Perfect Anomalous Reflection with a Bipartite Huygens’ Metasurface

Abstract: A new metasurface design offers a simple, practical approach to redirecting electromagnetic waves in an arbitrary manner with near perfect power efficiency over a wide range of angles and frequencies.

Eigenmode method for electromagnetic synthesis of diffractive elements with three-dimensional profiles

Abstract: We extend the rigorous eigenmode theory of binary surface-relief gratings to accommodate three-dimensional-modulation profiles, to formulate a synthesis problem for doubly periodic resonance-domain diffractive elements, and to demonstrate some of the problem’s symmetry properties. Several solutions for multiple beam splitters with ~90% transmission-mode diffraction efficiency are obtained by nonlinear parametric optimization. The polarization sensitivity and the required fabrication accuracy are analyzed for some solutions.

Eigenmode method for electromagnetic synthesis of diffractive elements with three-dimensional profiles

Abstract: We extend the rigorous eigenmode theory of binary surface-relief gratings to accommodate three-dimensional-modulation profiles, to formulate a synthesis problem for doubly periodic resonance-domain diffractive elements, and to demonstrate some of the problem’s symmetry properties. Several solutions for multiple beam splitters with ~90% transmission-mode diffraction efficiency are obtained by nonlinear parametric optimization. The polarization sensitivity and the required fabrication accuracy are analyzed for some solutions.