Performance of hemielliptic dielectric lens antennas with optimal edge illumination

The role of edge illumination in the performance of compact-size dielectric lens antennas (DLAs) is studied in accurate manner using a highly efficient algorithm based on the combination of the Muller boundary integral equations and the method of analytical regularization. The analysis accounts for the finite size of the lens and directive nature of the primary feed placed close to the center of the lens base. The problem is solved in a two-dimensional formulation for both E- and H-polarizations. It is found that away from internal resonances that spoil the radiation characteristics of DLAs made of dense materials, the edge illumination has primary importance. The proper choice of this parameter helps maximize DLA directivity, and its optimal value depends on the lens material and feed polarization. Index Terms: Beam collimation, dielectric lens antenna, directivity improvement, edge illumination, edge taper, hemielliptic lens.Comment: 5 pages, 9 figure

Circularly-Polarized Discrete Lens Antennas in the 60-GHz Band

This paper presents the design and demonstration of two circularly-polarized transmit-arrays operating in the 60-GHz band and generating a broadside beam and a 30°-tilted beam respectively. These arrays have a fairly simple structure with only three metal layers and are fabricated with a standard printed-circuit board technology. The simulated results show the performances of the unit-cells as well as the whole arrays, and detail their power budget. The experimental results in V-band are in very good agreement with the simulations and demonstrate very satisfactory characteristics. Power efficiencies up to 53.7% are reached with a 1-dB gain-bandwidth up to 9.1%, and low cross-polarization level

Optical and modal features of hemielliptic dielectric lenses

Any dielectric lens has a finite closed boundary and therefore is, in fact, an open dielectric resonator capable of supporting resonant modes whose Q-factor depends of the lens parameters (size, shape, and material). The hemielliptic lens, that is an essential building block of many mm-wave and THz antennas, is not an exception: it supports the so-called halfbowtie (HBT) resonances that can strongly affect performance of such antennas. In this paper we illustrate the interplay between the optical and modal features in the electromagnetic behaviour of hemielliptic lenses and highlight the drastic influence of the HBT resonances on radiation characteristics of lens antennas. We also discuss the difficulties associated with accurate description of the resonant phenomena in compact-size hemielliptic lenses with conventional techniques and provide recommendations on how to minimize the parasitic impact of HBT resonances on the antenna performance.Comment: 5 pages 6 figure

Unit-cell for dual-circular polarisation reflectarrays

International audience—A new unit-cell composed of two layers for dual-CP reflectarrays is proposed for the first time with the unique capability to reflect independently and simultaneously the two incident circular polarisations at the same frequency. The experimental results demonstrate that this unit-cell exhibits a 3.8% bandwidth around 8.4 GHz for a phase resolution better than 1.92 bits in LHCP and in RHCP. As a first step towards a reflectarray in dual-CP, this innovative unit-cell is studied in an array configuration. To increase the value of the maximum incidence angle up to 30°, a matching dielectric layer is placed over the cell

Unit-cell design for antenna arrays efficiently matched to uni-travelling-carrier photodiodes

International audienceWe present an antenna array with a backing reflector that allows one to obtain efficient matching to integrated sources or loads with low input resistance. In the infinite array limit, it is possible to describe the proposed unit-cell as an equivalent network with closed-form expressions for its different constituents. This analytic approach enables the preliminary design of arrays with improved matching efficiency for optimum power transmission/reception. The proposed solution has enabled an improved matching to a uni-travelling-carrier photodiode with a maximum improvement of 3 dB in the radiated power with respect to a 72-Ω antenna, and featuring a 50% bandwidth

A millimeter-wave inflatable frequency-agile elastomeric antenna

This letter reports a millimeter-wave frequency agile microstrip antenna printed on an ultrasoft elastomeric PDMS substrate. The microstrip patch antenna is supported by a PDMS membrane suspended over an air cavity. The distance H between the patch and the ground plane, and thus the resonant frequency of the antenna, are tuned using pneumatic actuation, taking advantage of the extreme softness of the PDMS membrane. A continuous frequency shift varying from 55.35 to 51 GHz ( ≈8%) has been obtained for a tuning range of H between 200µm and 575µm. In all configurations, the antenna remains matched and its radiation characteristics are very satisfactory