Marc Imbert

Design and Performance Evaluation of a Dielectric Flat Lens Antenna for Millimeter-Wave Applications

In this letter, a practical fabrication of a novel inhomogeneous gradient-index dielectric flat lens for millimeter-wave applications is presented. A previous theoretical design of a dielectric flat lens composed of different permittivity materials is now modeled and analyzed for a practical prototype fabrication and performance evaluation at 60 and 77 GHz. The measurement results at 60 GHz show that with the novel gradient-index dielectric flat lens antenna prototype, we can achieve up to 18.3 dB of broadside gain, beam-steering capabilities in both planes from -30° to +30° with around 15 dB of gain, and up to ±45° with around 14 dB of gain, with low sidelobe levels. At 77 GHz, the performance evaluation shows that we can obtain up to 18.9 dB of broadside gain, beam-steering capabilities in both planes from -30° to +30° with around 17 dB of gain and low sidelobe levels, and up to ±45° with around 15 dB of gain. This novel design leads to a low-cost, low-profile, and lightweight antenna solution, easy to integrate in a compact millimeter-wave wireless communication system.

Three-Dimensional Microfabricated Broadband Patch Antenna for WiGig Applications

The design, microfabrication, and characterization of a broadband patch antenna capable of covering the entire IEEE 802.11ad (WiGig) frequency band (57-66 GHz) are presented in this letter. A conductor-backed (CB) coplanar waveguide (CPW)-fed loop slot couples the energy to the patch antenna, resulting in a broad bandwidth. The feed circuitry along with the loop is formed on a quartz substrate (εr = 3.9, tan δ = 0.0002 at 60 GHz), on top of which an SU-8-based three-dimensional (3-D) structure with air cavities is microfabricated. The patch metallization is deposited on top of this 3-D structure. While the main role of the structure made out of SU-8 material is to provide a mechanical support for the patch metallization, the antenna takes advantage of the air cavities underneath, thus resulting in an antenna substrate with a very low loss. This, in turn, improves the overall antenna performances. The simulated and measured impedance characteristics agree well, showing ~15% bandwidth. Also, the radiation pattern results demonstrate the integrity of radiation pattern with reasonably constant gain values (average ~6.4 dB) in the broadside direction over the entire WiGig band.

Design of a dielectric flat lens antenna for 60 GHz WPAN applications

In this paper we present the design of a dielectric flat lens antenna to operate in the 60 GHz band for WPAN applications. In order to overcome the specific atmospheric attenuation, which characterizes the propagation in the 60 GHz band, high directive antennas are required. Moreover, due to high user random mobility in indoor environments, beam-steerable antennas are also needed. For these reasons, we propose a design based on a dielectric flat lens antenna with scanning capabilities from -30° to +30° with around 20 dB of gain in the whole entire band of interest (57 to 66 GHz), and up to ±60° of beam-steering capabilities with around 15 dB of gain. The dielectric flat lens also leads to low-profile antenna configuration, easy to manufacture and low-cost, in order to integrate the design together with a commercial RF CMOS chip.

Assessment of the Performance of a Metamaterial Spacer in a Closely Spaced Multiple-Antenna System

A metamaterial spacer composed of spiral resonators (SRs) and narrow metal strips has been tested to operate like a bidirectional artificial magnetic conductor (AMC) reflector at 2.45 GHz. The performance of the spacer has also been evaluated in a closely spaced multiple-antenna system applied to successfully increase the transmission capacity of a commercial wireless IEEE 802.11b router.

LTCC-based dielectric flat lens performance evaluation at 94 GHz

The design and performance evaluation of an inhomogeneous LTCC-based dielectric flat lens at 94 GHz is presented. A previously introduced dielectric flat lens design with its effective permittivity (εr) circularly distributed in a set of six discrete concentric rings is modeled and analyzed for a practical LTCC technology fabrication. The focusing capabilities of this lens prototype are numerically estimated and practically tested at 94 GHz, in order to evaluate its performance for automotive radar applications, passive imaging systems, or communication systems at this frequency, in which the beam-scanning and high-gain beams are desirable. Our numerical results indicate that we are able to obtain up to 21 dB of broadside gain and beam-steering capabilities from -52° to 52° with around 13.5 dB gain. Promising preliminary measurements at 94 GHz show that with the proposed LTCC-based flat lens antenna solution we can achieve beam-steering capabilities from -45 to +45° without appreciable pattern distortion.

Assessment of LTCC-Based Dielectric Flat Lens Antennas and Switched-Beam Arrays for Future 5G Millimeter-Wave Communication Systems

This paper presents the design, low-temperature co-fired ceramics (LTCC) fabrication, and full experimental verification of novel dielectric flat lens antennas for future high data rate 5G wireless communication systems in the 60 GHz band. We introduce and practically completely evaluate and compare the performance of three different inhomogeneous gradient-index dielectric lenses with the effective parameters circularly and cylindrically distributed. These lenses, despite their planar profile antenna configuration, allow full 2-D beam scanning of high-gain radiation beams. A time-domain spectroscopy system is used to practically evaluate the permittivity profile achieved with the LTCC manufacturing process, obtaining very good results to confirm the viability of fabricating inhomogeneous flat lenses in a mass production technology. Then, the lenses performance is evaluated in terms of radiation pattern parameters, maximum gain, beam scanning, bandwidth performance, efficiencies, and impedance matching in the whole frequency band of interest. Finally, the performance of the three lenses is also experimentally evaluated and compared to a single omni-directional antenna and to a ten-element uniform linear array of omni-directional antennas in real 60 GHz wireless personal area network indoor line-of-sight (LOS) and obstructed-LOS environments, obtaining interesting and promising remarkable results in terms of measured received power and root-mean-square delay spread. At the end of this paper, an innovative switched-beam antenna array concept based on the presented cylindrically distributed effective parameters lens is also introduced and completely evaluated, confirming the potential applicability of the proposed antenna solution for future 5G wireless millimeter-wave communication system.

Matching layer design to improve the performance of an inhomogeneous dielectric flat lens at millimeter-wave frequencies

In this paper, the design of a matching layer to increase the maximum achievable gain, reduce the back-radiation, and enhance the bandwidth performance of a dielectric flat lens antenna for millimeter-wave applications is presented. The performance of the original inhomogeneous gradient-index dielectric flat lens is compared with the performance of the lens with an inhomogeneous matching layer design. Our numerical results indicate that compared to the original flat lens design without matching layer, the lens with the matching layer delivers a better performance in terms of maximum achievable gain, back-radiation reduction, and bandwidth.

Ku-band flat lens design for satellite TV applications

In this paper, the design of a dielectric flat lens to operate in the Ku-band for satellite communications is presented. Modern dishes intended for home television are generally bulky and heavy. Moreover, the costs of installation and alignment with the desired satellite are high. Satellite television providers are therefore looking for alternatives to the traditional dishes that could provide narrow beamwidths (5° max.), high gains, low side-lobe levels and beam steering capabilities. To satisfy the aforementioned requirements, we propose a dielectric flat lens to steer and enhance the radiation of the feed in a particular direction. Our simulation results indicate that we can achieve up to 31 dB of gain with 2.3° beamwidth, and beam-steering capabilities from +15° to -15° in both azimuth and elevation with more than 28 dB of gain with around 4° beamwidth, with low side-lobe levels, in the entire frequency band of interest (from 11.7 to 12.2 GHz). Moreover, the proposed design leads to a low-profile antenna configuration, easy to manufacture and low-cost.