M. Himdi

High-Efficient and High-Gain Superstrate Antenna for 60-GHz Indoor Communication

A high-efficient and high-gain aperture coupled patch antenna with superstrate at 60 GHz is studied and presented. It is noted that adding superstrate will result in a significant effect on the antenna performances, and the size of the superstrate is critical for the optimum performance. The maximum measured gain of a single antenna with superstrate is 14.6 dBi, which is higher than that of a classical 2 x 2 array. It is found that the gain measured of a single antenna with superstrate increases nearly 9 dB at 60 GHz over its basic patch antenna. This superstrate antenna gives a very high estimated efficiency of 76%. The 2:1 measured VSWR bandwidth with superstrate is 6.8%. The radiation patterns are found to be broadside all over the frequency band. Also, this letter explains a comparison to another source of parasitic patch superstrate antenna with normal microstrip coupling. It is found that aperture coupling is better for high-gain antenna applications.

A Novel Broadband Eighth-Wave Conical Antenna

A novel antenna is composed of a conical monopole with metallic parasitic elements and a capacitive disk placed above a ground plane. A dielectric substrate is used in order to optimize the performances. This antenna provides broadband characteristics and omnidirectional radiation patterns over the whole bandwidth with a height limited to a one eighth wavelength associated to the lowest frequency. Simulations and experiments demonstrate that this structure exhibits a 2.9:1 impedance bandwidth with VSWR below 2:1 and very good radiation patterns and gain in spite of a size extremely reduced.

Circuit Modeling of a Small Broadband Conical Antenna

Equivalent circuit modeling methodology is proposed in this letter for a small broadband antenna composed of a conical monopole with metallic parasitic elements, a capacitive disk, and a dielectric substrate around the feed region. This omnidirectional antenna provides broadband performances over the whole bandwidth with a height limited to a one-eighth wavelength associated to the lowest frequency. The proposed modeling procedure presents excellent agreement with electromagnetic and experimental results.

Multibeam Antenna in Millimeter Waves

This paper deals with a multibeam antenna in 60 GHz band. This structure is based on a Butler Matrix which fed a four printed antenna array. Two different solutions are presented to avoid the crossing point of the microstrip line : a microstrip-thick slot-microstrip transition or two hybrids 90°. The authors present the feeding line network of the matrix and compare results for the two solutions in term of losses, radiation pattern and tilt angle.

Millimeter Wave Reconfigurable Antenna Based on Active Printed Array and Inhomogeneous Lens

This paper deals with radiation pattern reconfigurable antenna in millimetre wave range. An active printed antenna array is designed in 24 GHz band and feed an inhomogeneous lens (Half Maxwell Fish Eye) to obtain reconfigurable patterns and in particular sectorial and directive cases. In the first part, the authors describe a four patches multilayer active array which allows achieving radiation pattern control by associating a commutator to each element and by changing the fed patches number. In a second part, this array feed an inhomogeneous lens to shape radiation pattern.

Use of RF MEMS and micromachined parts to realize highly integrated V band active feed for satellite antennas

Micromachining and microelectromechanical systems (MEMS) technologies can play a key role in miniaturization of satellite antenna front-ends. Alcatel Alenia Space France has demonstrated for the first time the operation of a V band integrated active feed combining 3D stacking concepts and micromachining technologies. The realized integrated module size is 35 times 35 mm2 with a thickness of 7 mm including miniaturized DC and RF connectors. In this paper, we present the latest test results obtained on this MEMS based active antenna

Far field millimetric band antenna test facility : Positioning procedure using phase measurements

Since several years IETR has been conducting active research activities on the modelling and design of millimetric radiating structures and devices. The experimental validation of innovative designs and homemade electromagnetic CAD tools is of uppermost importance. To this end, prototyping capabilities and complementary sets of antenna test facilities at millimetre waves are available for routine experiments (e.g. [18-110] GHz far field chamber, [2-110]GHz coaxial vector network analyser). In such a context, antenna measurements are considered as a key step of the research process. Even though our measurements facilities are not used for certification purposes, they need to provide reproducible, reliable and accurate data for a wide diversity of antenna topologies and dimensions. Then, the definition of the same coordinates system for measurements and simulations remains a sensitive point. We present in this paper an easy-to-use positioning procedure based on phase measurements from Ka-band to W-band. This technique is briefly described in Section 1. Various experimental results are given in Section 2 and conclusion are drawn in section 3..

RCS measuring procedure and distribution for automotives in the context of ITS

This paper presents a measuring procedure for vehicle RCS estimation at 77 GHz. The RCS measurements were performed on a Ford Focus Break model vehicle and a Peugeot 206 and are presented in function of the relative angular position of the vehicles with respect to the radar system.

Electromagnetic modeling of stratified inhomogeneous lenses fed by real sources

An analytical method, the mode matching technique based on spherical wave functions, has been described and applied to both spherically and hemispherically stratified lenses fed by an open-ended waveguide such as respectively, multishell Luneburg and half Maxwell fish-eye lens antennas. A way to deal with any real source as well as to handle hemispherical lenses is explained, yielding to remarkably accurate results. The agreement between the far field radiation patterns and directivity obtained by the analytical method, commercial softwares and measurements are indeed excellent. A semi analytical method, allowing to deal directly with arbitrary shaped stratified lenses, is now under investigation.

Multilayer antenna array in Q band for spatial communications

This paper deals with a multilayer printed antenna array. This study takes place in European MIPA project [1] concerning an antenna prototype which is apart of Q band (50 GHz) one-feed-per-beam antenna reflector. In millimetre waves, it is highly required to separate active layer (MEMS, MMIC, ‥) and radiating elements to avoid electrical spurious generated by coupling radiation. This separation is done with a very thick metallic support (2 mm). Moreover, this thick ground plane is important for thermal dissipation aspect. In this aim, the authors present an original feed of antenna array via a H shape thick slot transition. Results of antenna array radiating patterns, power gain and efficiency are given in the considering bandwidth (47.2 to 50.2 GHz).