Angular aperture

About: Angular aperture is a research topic. Over the lifetime, 1771 publications have been published within this topic receiving 27257 citations.

Imaging lens, optical apparatus and method for forming image using this imaging lens

Abstract: An imaging lens includes a first lens group having a positive refractive power, an aperture stop, and a second lens group having a positive refractive power, which are disposed in order from an object. The first lens group has a first lens component having a negative refractive power and a second lens component having a positive refractive power, which are disposed in order from the object, and conditions expressed by the expressions 0.12

Flat-base broadband multibeam Luneburg lens for wide-angle scan

Abstract: In this paper, we present the design of a flat-base Luneburg type of lens antenna, designed for wide-angle scan. The antenna consists of a 11-layer lens, fed at its base by a array of waveguides. The lens is broadband and has a high aperture efficiency, only 1 dB below that of a reference aperture antenna with uniform amplitude and phase distributions. Its sidelobe level is –21 dB at boresight and –13 dB when the scan angle is . It shows good performance when compared to the flat Luneburg lens previously reported in the literature, in terms of gain, scan capability, as well as ease of fabrication. It is shown to have the capability of producing multiple beams simultaneously, multiple angle, scan capability. Two different methodologies have been used to design the feed array of waveguides for the lens. The first of these utilizes a conventional perfect electric conductor waveguide, while the second employs materials for the guided wave region that has a high permittivity at frequencies at which metals beco...

Complex source representation of time harmonic radiation from a plane aperture

Abstract: Developed here is a new complex source representation for time harmonic radiation from a plane aperture which is the Kirchhoff's spatial convolution formula of a complex plane aperture with the complex aperture field being the analytic extension of the original aperture field. A systematic study for a one-dimensional linearly phased cosine aperture distribution confirms the effectiveness of the new method in the simulation of the time harmonic radiation. >

Dual aperture lens

Abstract: A variable aperture lens has a fixed aperture stop inside the lens and a variable aperture stop located outside the lens. When the lens is operated at its widest effective aperture, the effective aperture is defined by the fixed aperture stop. When it is operated at its narrowest effective aperture, the effective aperture is defined by the variable aperture stop. This permits highest corrections for the widest aperture but with a lens that is free of the cleaning and other difficulties of a variable interior aperture.

The Diffraction of an Electromagnetic Wave by a Large Aperture

Abstract: With the aid of methods previously developed, an approximate expression is obtained for the difference from unity of the transmission coefficient for plane waves at normal incidence of a large aperture of rather general form in a plane perfectly-conducting screen. The coefficient is expressed in the form of one or more line integrals taken around all (or part) of the aperture rim. These may be evaluated analytically in certain cases, e.g. a circular or elliptical aperture. In the former case the result agrees with that derived elsewhere; the ellipse is considered in some detail in the present paper, and the transmission coefficient is evaluated for a range of eccentricities. The results appear to be in qualitative agreement with the limited experimental data available.