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International audience; Transmit-arrays (TAs) are a popular cost-effective solution for high-gain antennas at millimeter waves (mmW). The design of these antennas relies on the fine tuning of the sub-wavelength unit-cells that compose the aperture. The intricacy of the unit-cells increases as new features are implemented, such as dual-band operation and wide-angle beam steering, making this antenna even more computationally challenging. In this work, a high gain (25 dBi @ 20 GHz and 28 dBi @ 30 GHz) multi-scale Ka dual-band TA for beam-steering applications is analyzed using a massively parallel implementation on multicores clusters of the Finite Element Tearing and Interconnecting method, with a two Lagrange Multiplier (FETI-2LM) technique. The main contribution of this work is the implementation of 3D non-periodic grids with sub-domains of different scales, that is suitable for proper modelling of different regions of the antenna (horn feed, lens cells, air region). An automatic batch file procedure is proposed for the TA meshing, allowing the limited set of constitutive unit-cells of the TA to be meshed separately. Additionally, we are using a block-Krylov strategy to efficiently capture the TA beam-steering capability, without restarting from scratch the interface problem for each feed position. Since other Finite Element Method (FEM) results were not accessible due the size of the problem, the FETI-2LM numerical results provided in this work are compared with other MultiLevel Fast Multipole Method (MLFMM) [1] and Transmission Line Modeling Method (TLM) [2] of CST Microwave Studio solvers, as well as with the measured results of the corresponding Ka dual-band prototype. The computational infrastructure has been used only a fraction of its capacity. Therefore, a much higher gain design (40 dBi) can be assessed, opening a new realm of applicability of TAs in the space segment usually occupied by reflector-based solutions.

This letter presents a first step toward the design of an enhanced multifeed EBG structure that serves as a focal-plane array for a Ka-band reflector for space applications in the 29.5-30-GHz band. The desired Earth coverage is the starting point for the antenna design. As shown in this letter, significant coupling can deteriorate the performance of the multifeed EBG antenna. In order to demonstrate this, the results are compared to those of the single-feed reflector antenna. Filters are then connected to the multifeed antenna ports to control the coupling in a constructive way and obtain good radiation characteristics. Finally, the global feed architecture (EBG structure + filters) is used to illuminate a reflector antenna in order to characterize the antenna performance (C/I ratio, EoC gain).

This paper describes the method of design of an electromagnetic bandgap antenna. This antenna is able to radiate in vertical, horizontal, and dual polarization with an omnidirectional pattern in azimuth. Through the given abacuses, it is possible to conceive the structure to obtain specific performances in each polarization. To illustrate this purpose, a dual polarization antenna, operating in the lower HiperLAN frequency band, i.e., 5.15-5.35 GHz, is presented.

An `EBG antenna (Electro-Magnetic Band Gap)' is built with a semi-reflective screen over a set of horns feeding a reflector. A clever application of the partial spreading of the electro-magnetic field in such a structure is to provide `overlapped radiating apertures', which generate `overlapped beams' when feeding a reflector. This is a unique single-antenna solution, fitting with multi-beams missions from satellite which require low gain ripple over a regional coverage, e.g. for high data-rate communication in Ka-band. A prototype has been optimised and built, as a co-operation between Thales Alenia Space France & XLIM/Antenna Lab, supported by space agencies ESA & CNES. Adding a very light meanderline polariser (honeycomb based) transforms the alternated orthogonal linear polarisations into orthogonal circular ones, coping with most recent missions.

This article describes the design of an ultrawide band (UWB) biconical antenna operating in the 400–3000 MHz frequency band. The antenna will be used for high-rate communication applications. The method for designing an UWB biconical antenna will be given. As the antenna must operate starting from 400 MHz, the size of the designed antenna will exceed the dimensions constraints, required in the specifications. Thus, the antenna edges are curved, which allows us to decreasing its dimensions while keeping the same performances. Finally, a prototype of the antenna is fabricated and measured, and the measured results are compared to the simulated ones. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:404–408, 2014

This article presents a solution to bypass the cost and flatness problems for low-cost electronic devices which is the inkjet printing. This process allows the use of flexible substrate materials, such as paper or plastics, suitable for a real-to-real process. More precisely, the procedure to design an electromagnetic band gap antenna using frequency selective surfaces and coplanar wire-patch antenna for 2.5-GHz applications is detailed. This kind of antenna has been designed before, but the used substrate is expensive and thin. These antennas were fabricated using inkjet printing technology on a flexible, low-cost paper substrate using a simple, fast, and cheap process compared to the photolithography technology. The design characteristics of the antennas were verified and the experimental measurements were successfully compared to the simulated ones. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1520–1526, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27613

International audience; This article presents a first step towards the design of a multi-feed circularly polarized EBG antenna which serves as a reflector focal array. The circular polarization is obtained by using a multilayer meander lines polarizer, placed above a linearly polarized EBG antenna. The details of the antenna and the polarizer are given and the "transparent" effect of the polarizer on the antenna feed performance is emphasized after comparing the performance with and without the polarizer. The designed antenna is used to illuminate a reflector antenna for RX Ka-band space applications [29.5 - 30] GHz, and the coverage performance will be shown.

International audience; We present the design of a multibeam reflector antenna fed by a multifeed dual-band electromagnetic band gap (EBG) antenna to achieve a high-gain multispot coverage for space applications. First, we design a dual-band EBG antenna in monofeed configuration. This antenna is composed of double-layer frequency selective surfaces (FSSs) arranged in the longitudinal direction and a square horn as a feed. Then, the same antenna in multifeed configuration is studied, and the results are compared to those obtained in monofeed configuration in order to emphasize the problem of coupling, generally encountered in multifeed configuration. Consequently, filters are used in order to reduce the parasitic interferences and obtain good radiation characteristics. As shown in this paper, the same EBG phase center is obtained in both frequency bands. Finally, we have studied the whole system composed of the offset reflector and the multifeed EBG dual-band antenna. An edge of coverage (EOC) gain higher than 42 dBi and sidelobes levels lower than −18 dBi are obtained over all spots.

The demand for multimedia communications via satellite systems have increased considerably in the last years. Normally, the satellite coverage is composed of a hexagonal lattice of many small beams. An example of an experimental satellite coverage named “Agora” is composed of 40 0.65°-diameter spots, using 4 frequency channels in a 4x reuse scheme with the same circular polarization. A first solution which meets the requirements of such a mission (C/I, efficiency, roll-off) is the use of 4 Rx/Tx parabolic reflectors on the same satellite, providing each a family of spots at the same frequency. This solution has the drawback of heavy weight and the challenging accommodation of 4 reflectors on the platform. These 4 reflectors could be replaced by only one, when using a focal array which is capable of generating a specific illumination law (overlapped beams). This focal array could be composed of an active BFN which is, unfortunately, expensive and has moderate RF efficiency. Several studies have shown that overlapped beams could be obtained by using multi-feed EBG antennas [1, 2]. The major problem of these structures is the mutual coupling between different feeds. It was demonstrated recently that suitable filter designs could be connected to each feed [3, 4] in order to ensure the isolation between different channels and also to reconstruct properly the radiation patterns which are otherwise disturbed by the coupling. In [4] and [5] it is shown that the use of a matched multi-feed EBG antenna with 2 linear polarizations and 2 frequency channels provides a 4x reuse scheme that simplifies the system architecture. In fact, the use of a matched antenna relaxes the need for the filters to provide matching inside the operating band; they just need to act like a short circuit with the appropriate phase outside their operating band, in order to reconstruct properly the radiation patterns. On the other hand the use of 2 frequency channels reduces the number of required filters (2 filters instead of 4). Finally, linear polarizations are considered in order to prevent the design of bulky filters for circular polarization (6 poles filters with 6 cavities are needed to ensure the transmission of circularly polarized wave and isolation between channels). In this paper, a metallic multi-feed EBG antenna operating in Ka band [29.5–30] GHz is presented, and its performances before and after connecting the filters will be shown. Finally, this antenna is used to illuminate a reflector and the coverage characteristics (C/I) will be given.

International audience; A new simplified methodology for the design of microwave cavity filters has been presented. The presented work is based on the optimization of Belevitch polynomials and inspired from the Simplified Real Frequency Technique (SRFT). one can bypass the use of computationally expensive circuit simulation softwares which are used to optimize the lumped element circuit model of the cavity filters. The procedure is applied for the design of filters for a multi-feed filter-antenna subsystem for space application.

This paper presents an additional work on a previous EBG cylindrical antenna in order to conceive a steerable antenna for Radar applications which require the coverage of the horizontal plane with a high gain (higher than 25 dB). The already designed antenna provides 18 beams with 15 dBi of maximum directivity. That is why some modifications were applied on it in order to obtain more beams in the horizontal plane (30 beams) and increase its gain. Moreover, the theories of cylindrical arrays in the horizontal plane and the multi-feed in the vertical plane are used which allows further gain improvement and reaching the required one.

This article presents a new method to realize sectoral antennas for base station by incorporating metallic partially reflecting surface (M-PRS).The main idea consists in inserting simple radiating elements, as patches, inside a Fabry-Perot cavity resonator. This consists of a ground plane, where the feeding system rests covered by a rectangular M-PRS. A patch array is used as a feeding structure to enhance directivity and radiation bandwidth. A rectangular M-PRS antenna for the uplink UMTS frequency band [1.92–1.98 GHz] working in vertical polarization is designed, and its performances are disclosed. Finally, a prototype is realized and the experimental measurements are compared to the simulated ones. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:990–994, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25044

International audience; We present in this letter the study of a multibeam antenna for telecommunication networks by using cylindrical electromagnetic band-gap (EBG) structures. The EBG structure behaves as a partially reflecting surface (PRS) and enhances the directivity of a simple radiating source. We begin by presenting the principle of the multibeam antenna, and then we present a first version, conceived to operate in WiMAX band [5.45.7] GHz. Simulation results of this antenna will show us that the strong mutual coupling between the different excitation sources of the EBG structure badly influences its performance. In order to reduce the mutual coupling, metallic walls are inserted between the excitation sources. Moreover, excitation sources have been changed to improve the radiation performance of the antenna. A prototype of the final antenna is fabricated to validate our simulation results, and the measurements results are compared to the simulated ones.

This paper presents the study of a new 4 x 90° sectorial metallic EBG antenna. The aim of this study is to increase the range of an EBG omnidirectional antenna by enhancing its gain, using the same EBG material. The procedure is based on dividing the omnidirectional pattern into 4 sectorial patterns with a radiation beam width of 90° for each. (6 pages)