Jonathan Bor

Foam Based Luneburg Lens Antenna at 60 GHz

An innovative technological process is investigated to easily manufacture inhomogeneous Luneburg lenses. A unique foam material is drilled and pressed to achieve the difierent dielectric constant needed to follow the index law inside the lens. The performance of such 60GHz antenna is described and the antenna prototype is measured in terms of gain and radiation patterns. The results show a good e-ciency (60% with a directivity of 18{19dBi) and demonstrate the feasibility of this kind of Luneburg lens, through the use of a simple technological process. The lens with a diameter of 56mm and a thickness of 3mm operates in the 57{66GHz bandwidth. The magnitude of S11 parameter is under i10dB in the whole bandwidth and an half-power beamwidth of 5 - and 50 - in H-plane and E-plane respectively is reached.

Technological Process to Control the Foam Dielectric Constant Application to Microwave Components and Antennas

A technological process to control the foam dielectric constant, an important issue for the design of microwave components and antennas, is described. For that purpose, the use of different commercial foam materials has been considered. This kind of foam substrate is made of original material (Polyvinyl chloride, resin, and...) into which gas is injected. Therefore, the dielectric constant of such foam is close to one. It can be increased by expelling the gas out of the foam material. The authors are presenting the technological process used to expel the gas by pressing a foam slab at relatively low temperature (90 °C). Because of this technological process, the dielectric constant variation can be controlled by the ratio between the initial and final slab thickness. It holds a great interest for the design of microwave antennas and circuits. Indeed, the dielectric constant inside gradient index lenses (Luneburg, Maxwell fish-eye, and Fresnel lenses) must follow a particular law to obtain the desired radiation capabilities. The results of materials characterization are presented to validate the technological process. Foam-based antennas and components are also shown to illustrate the interest of the process.

Design and characterization of a foam-based Mikaelian lens antennas in millimeter waves

The design principles and radiation performances of Mikaelian lens antennas are presented. The ways to manufacture gradient index lenses are briefly reviewed. An innovative technique based on the variation of the foam density is described and applied to the Mikaelian lenses. This yields low cost and lightweight gradient index lenses. The focusing properties of Mikaelian lenses are compared numerically to Luneburg lenses. A foam-based planar Mikaelian lens antenna is manufactured and its radiation performances are characterized at 60 GHz. With its flat shape in contact to the primary source, the cylindrical Mikaelian lens turns out to be, for focusing purposes, an interesting alternative to the well-known Luneburg lens.

Millimeter-Wave Fresnel Zone Plate Lens with new technological process

Fresnel Zone Plate lens (FZPL) antennas working in the V and W band are reported in this paper with half and quarter phase correction respectively. A low cost and straightforward technological process is used to manufacture the dielectric lenses using only one foam material where the dielectric constant is controlled. Simulation and measurement results are in good agreement that confirms the viability of such a process to fabricate inhomogeneous structures. Good loss efficiency of 73 and 55% are obtained at 60 and 85 GHz respectively with the two different FZPL designs.

Creation of a gradient index structure inside foam material - Microwave application for a lens antenna at 60 GHz

Creating a gradient index into a dielectric structure is a major issue nowadays for the design of microwave components and antennas, especially for inhomogeneous lenses as Luneburg, Fresnel and Maxwell Fish-eye. The use of a foam material and a simple technological process can allow this. Because a foam material is composed of air bubbles, and core materials (resin, PVC, ...), removing the air will increase the density of the foam and so increase its dielectric constant. The authors present a simple technological process to expel the air from a piece of foam in order to increase the permittivity of the foam. This is then applied to the design of a Luneburg lens antenna at 60 GHz.