Shaped Lens Antenna Research Articles

Focal Region Ray Tracing of Conventional and Shaped Lens Antenna

Multibeam lens antennas are useful for 5G mobile communication systems. For multibeam design, feed position determination of specified lens becomes an important subject. The feed position data can be obtained from focal region ray tracing. In this paper, asimple and convenient ray tracing method by using the MATLAB function of “polyxpoly” is proposed. To evaluate the program, focal region ray tracing on conventional hyperbolic planar, spherical convex, and Abbe’s sine conditionlens arepresented in this paper. For focal region ray tracing, parallel incident ray is considered. The incident ray’s angle is changed from 0 degree to 30 degrees with an interval of 10 degrees. On hyperbolic planar and spherical convex lenses, ray concentration at the focal regionis distorted at incident angle of 10 degrees and above. On Abbe’s sine condition lens, good concentration is maintained until 20 degrees. Concentration points agree well with the theoretical value. Therefore, the correctness of the program is ensured.

Broadband Integrated Lens for Illuminating Reflector Antenna With Constant Aperture Efficiency

A new integrated shaped lens antenna configuration is described with frequency stable radiation pattern and phase center position across a broad 1:3 frequency band, which can be used for focal plane reflector feeding in quasi-optical radio telescope systems. The lens is compatible with the integration of ultrawideband uniplanar printed feeds at its base and equally broadband mixing devices, like the Hot Electron Bolometer (HEB), although these are not used in the present work. Measurements on a scaled mm-wave lab prototype have confirmed stable performance versus frequency, with only dB directivity variation, and better than 94% Gaussicity, thanks to the possibility to impose a predefined output radiation pattern template. Simulations were performed to test the illumination of an off-set parabolic reflector by the lens radiation pattern, which confirmed reasonably constant aperture efficiency in the order of 78% across the 100% bandwidth.

Improvement of Beam Scanning Characteristics of a Dielectric Lens Antenna by Array Feeds

In the Intelligent Transportation System, millimeter waves are used and antennas are required beam scanning ability. In the millimeter wave operation, a lens antenna is one of the prominent candidates which achieves wide angle beam scanning. Wide angle scanning can be achieved by introducing Abbe sine condition to lens surface shaping. Authors designed the shaped lens antenna that could achieve beam scanning ±30°. The narrow beam widths were maintained on the scanning plane. However, the beam widths were broadened on the transverse plane and large gain reduction was appeared. It was clarified that the reason of this beam deterioration was due to the phase delay on the antenna aperture. In this paper, an array feed composed of a group of rectangular horns is employed to compensate the phase delay on the antenna aperture. In designing the array feed, because there were no examples of phase radiation pattern synthesis, a new radiation pattern synthesis method is studied. Ability of the weighting matrix contained in the Least Mean Square synthesis method is paid attention. Adequate weighting matrix is found out. Satisfactory phase radiation pattern that can compensate the phase delay and an adequate amplitude radiation pattern are achieved. As a result, the improvement of scanned beam widths and antenna gains through the array feed are ensured. And adequate horn arrangements of the array feed for improving scanned beam are clarified. Moreover, in order to examine the realization of an actual array feed, the exact electromagnetic simulation is conducted. The validity of the radiation pattern synthesis is clarified.

Assessment of design procedures of nearly axis‐symmetric shaped lens antennas: A comparative study between 2‐D and 3‐D formulations

AbstractShaped integrated lens antennas (ILAs) are attractive for beam‐shaping applications at millimeter waves and specific synthesis methodologies have been proposed for their design. The purpose of this paper is two‐fold. First, we focus on the particularities associated with the geometrical optics/physical optics (GO/PO) analysis of numerically‐specified arbitrarily‐shaped ILAs, namely (i) the interpolation procedures of generic 3‐D ILAs and (ii) the computation of their surface curvature parameters. In particular, new closed‐form expressions of the principal radii of curvature of a curved interface are established. Second, two synthesis procedures, previously implemented for nearly axis‐symmetric and arbitrarily‐shaped ILAs, are compared and discussed numerically and experimentally. To this end, two ILAs made from Teflon are designed and fabricated, starting from the same radiation specification at 58.5 GHz (the amplitude template is a circularly‐symmetric pencil beam). Both prototypes are fed by a 2 × 2 elements microstrip antenna array. The experimental results are in satisfactory agreement with the simulations. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 615–622, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22198

Design and optimisation of axisymmetric millimetre-wave shaped lens antennas with directive, secant-squared and conical beams

The paper investigates the optimisation of rotationally-symmetric shaped dielectric substrate lenses at millimetre wave frequencies. The aim is to determine the best lens profile that complies with an arbitrary desired far-field power template. The design procedure is briefly described in three main steps. First, determination of the starting lens shape using an analytical geometrical optics (GO) formulation; secondly computation of the radiation characteristics of the lens using a hybrid GO-PO (physical optics) technique accounting for diffraction effects and, thirdly, iterative optimisation of trial lens profiles using a local minimisation procedure based on a multidimensional conjugate gradient method (M-CGM). The characteristics of the optimisation algorithm are then studied numerically, in terms of convergence speed and analysis of sensitivity. To this end, the authors design, discuss and compare several shaped lenses radiating directive, secant-squared and conical beams. These various examples demonstrate very good performance and promising potentialy of optimised lens antennas for shaped-beam applications.

Design and Analysis of Several Kinds of Dielectric Lens Antennas

This paper focuses on the design and analysis of several kinds of dielectric lens antennas and their application at millimeter waves and sub-millimeter waves. The lenses analyzed include refractive lens and diffractive lens such as hyperbolic lens antenna, binary diffractive lens antenna and shaped lens antenna. Our purpose is to optimize the performance of the lens antenna so as it has low side lob level, insertion loss and thin thickness. Finite element method (FEM) based on the weak form of Helmholtz equation is used to analyze electromagnetic characteristic of the lens antennas; and the radiation patterns of the lens antennas are presented.

A coma-corrected multibeam shaped lens antenna, part II: Experiments

A dielectric lens based on the shaping technique described in Part I of this communication was fabricated and tested. This lens was shaped to control the sidelobes and zoned for improved scanning characteristics. Basic antenna measurements were conducted and excellent performance results have been observed. In the prototype lens system with unmatched surfaces, a 4 dB crossover between adjacent beams of -30 dB sidelobes was obtained. The beam was scanned up to \pm 12\deg without significant coma degradations. This coma-corrected zoned lens was developed for satellite multibeam applications. The multibeam antenna so designed not only reduces the total costs and the payload burden, but also enhances the system reliability and the overall gain compared to a conventional design because no complex feed network is required.