A Class of Lightweight Spherical-Axicon Dielectric Lenses for High Gain Wideband Antennas

Abstract

A class of lightweight spherical-axicon-like dielectric lenses suitable for enhancing broadband antennas performances is presented. The proposed lenses, sized according to a reference massive lens, are formed by thin dielectric sheets spaced equiangularly on the azimuth plane (petal-shaped lens), or regularly orthogonally arranged along the lens axis (disks-shaped lens), thus yielding construction simplicity and significant weight reduction. While petal-shaped dielectric lenses are shown to yield mild gain increase, lenses made by thin dielectric disks, orthogonally periodically arranged along the lens optical axis, offer performances much closer to those achieved by comparable massive refractive spherical-axicon dielectric lenses. The time-domain and the focusing characteristics of the proposed lenses are investigated. Then, a Floquet's mode-based model is proposed to describe the stop-band characteristics of stacked-disk lenses, illustrating the mechanism underpinning their sudden performance degradation observed at the stopband onset frequency. Full-wave analyses, based on a locally conformal finite integration technique (FIT), implemented in CST Studio Suite™ and validated by measurements or highly accurate FEM simulations, illustrate the excellent characteristics of the proposed lenses to operate with narrowband as well as ultrawideband (UWB) waveforms.INDEX TERMS Dielectric resonator antennas (DRA), high gain wideband antenna, petal-shaped dielectric lens, spherical-axicon dielectric lens, stacked-disk dielectric lens, traveling-wave antennas, Vivaldi antenna, wideband dielectric lens.

A Wideband High-Gain Circularly-Polarized Dielectric Horn Antenna Equipped With Lamé-Axicon Stacked-Disk Lens for Remote Sensing, Air Traffic Control and Satellite Communications

“…Notice that, while the massive lens has a weight equal to 50 g, the one with stacked disks has a weight of only 14 g (equal to 28% of the weight of the massive lens) even though the same realized gain level is achieved. These remarkable characteristics confirm the fact that a stacked-disk lens reduces manufacturing cost and complexity and, therefore, is more suitable in those applications where weight is a key requirement, such as avionics and satellite applications [24].…”

“…The dielectric horn transfers the RF energy from the excitation slot region to a suitably shaped lightweight dielectric lens, whose purpose is to enhance the realized gain while keeping the antenna weight limited. To reduce weight and manufacturing complexity, a stacked-disk dielectric lens has been adopted in place of the massive counterpart as it exhibits similar electromagnetic field focusing capability but in combination with an extremely lower weight [24]. These features can be exploited in avionics and satellite applications where weight and manufacturing costs are key requirements.…”

“…A tapered microstrip line (characteristic impedance 50 ). Even if, as suggested in [24], the required separation between the disks forming the lens may be achieved by means of a thin dielectric rod (see [24]), for construction simplicity lightweight disks composed, of a dielectric foam (Styrodur® 3000 CS by Weston) having a thickness 0.348 , were employed as spacers (see Fig. 1b).…”

“…Finally, a stacked-disk dielectric lens with the same envelope as the massive counterpart was introduced. Such lens, designed according to the formulas reported in [24], is composed of five dielectric disks having thickness (that is equivalent to that of the massive lens) with a stop-band frequency of about 17…”

Ultra-Wideband Coplanar Vivaldi Antenna Array With Dielectric Patch Antenna for Grating Lobes Suppression

“…Another approach by surrounding the Vivaldi antenna with either a low dielectric constant material or a 3D phase lens to improve the gain and radiation performance was reported [29], [30]. Also, a 3D massive dielectric lens was added at the aperture end of the Vivaldi antenna [31]. These 3D surrounding materials showed an improvement in the gain and radiation pattern with SLL suppression.…”