Laurent Desclos

Active metallic photonic band-gap materials (MPBG): experimental results on beam shaper

We focus our attention on the possibilities to control the beam radiated by antennas, which are initially omnidirectional using active metallic photonic band-gap materials (AMPBG). In fact, MPBG composed of continuous or discontinuous wires present different and interesting characteristics when they are used as an antenna reflector or a radome. Adding active components on wires allows one to switch from continuous to discontinuous structures. Wires with active elements on can then be placed inside a structure, which shapes the beam radiated by a dipole antenna. Experimental results show that it allows one to switch on/off the beam or to change its shape.

Mobile handset system performance comparison of a linearly polarized GPS internal antenna with a circularly polarized antenna

There is a popular believe that the GPS antenna has to be right hand circularly polarized (RHCP). But, the circularly polarized signal is susceptible to deformation in the presence of multi-path environment. With the integration of GPS functionality in consumer products, especially in mobile handsets, chances are, the consumers are going to use these GPS-enabled devices mostly in an urban environment. And multi-path is omnipresent in these environments. Linearly polarized (LP) signal is less susceptible to distortions from surrounding environment. Therefore, a low profile, omni-directional linearly polarized antenna was developed. The number is satellites tracked, and the number of satellites used for navigation purposes were observed. The Carrier to Noise Ratio in dBHz was evaluated for each satellite used. The measurement results for both antennas in realistic environments will be presented.

A 5-GHz-band multifunctional BiCMOS transceiver chip for GMSK modulation wireless systems

This paper reports the first multifunctional 0.4-/spl mu/m BiCMOS-based transceiver chip developed for 5-GHz-band Gaussian minimum-shift keying modulation wireless systems. The chip integrates a low-noise radio-frequency amplifier, a down-mixer, and an intermediate-frequency (IF) amplifier in the down-converter path; an IF amplifier, a limiter, an up-mixer, and a buffer amplifier in the up-converter path; and a frequency doubler and a local oscillator amplifier in the local oscillator path. The chip featuring gain attenuation as well as standby mode operation uses a single 2.6-5.2-V bias voltage and dissipates 56 mW in receive mode and 66 mW in transmit mode. The transceiver chip size is 3.0/spl times/2.4 mm/sup 2/.

A sub-nanosecond resonant-type monolithic T/R switch for millimeter-wave systems applications

This paper is concerned with the design consideration, fabrication process, and performance of a V-band monolithic transmit/receive (T/R) switch for millimeter-wave wireless networks applications. The developed switch integrated circuit (IC) has a novel structure in which to pass a signal, it presents a parallel resonant circuit to the signal by forward biasing a pair of switching heterojunction FETs (HJFETs), but to block the signal, it presents a series resonant circuit to the signal by reverse biasing the switching HJFETs. With a control voltage of 0/3.2 V, the developed T/R switch exhibits a minimum insertion loss of 3.9 dB, a maximum isolation of 41 dB, and a high switching speed of 250 ps, over 57-61 GHz. The monolithic T/R switch chip size is 3.3 mm/spl times/1.7 mm.

A high-speed resonance-type FET transceiver switch for millimeter-wave band wireless network

This paper concerns with the design consideration, fabrication process, and performance of a CPW monolithic AlGaAs/InGaAs HJFET switch for V-band wireless networks applications. The Switch utilizes a resonance concept in order to either pass, or to block a signal by presenting, respectively, a parallel, or a series resonant circuit to the signal. A developed T/R switch exhibits state-of the art switching-speed and isolation of 250psec and 41dB, respectively, and an insertion loss of 3.9dB ovr V-band frequencies.

A K-band monolithic CPW oscillator co-integrated with a buffer amplifier

This paper describes the design approach, fabrication process, and performance of a monolithic CPW oscillator incorporating a buffer amplifier on the same chip, for K-band wireless network applications. At 21 GHz, the output power of the oscillator recorded 17 dBm with an overall DC-RF efficiency of 22%. By changing the length of a source feedback line, the oscillation frequency was varied up to 26 GHz. For all cases, the output power remained higher than 16 dBm.<<ETX>>

An interdigitated printed antenna for PC card applications

A quarter-wavelength diversity patch configuration for the 2.4-GHz ISM band PC card application is reported. The structure is based on partly interdigitation of two quarter wavelength separated patches through a set of fingers for achieving the required space diversity on single side printed substrate with an easy matching on 50 /spl Omega/, high cross-polarization and within a given maximum space of 30 mm/spl times/50 mm. Measured antenna patterns for the developed structure are the same as for a classical patch and the bandwidth for a VSWR less than two is 2% with a maximum gain of 1.5 dB. This antenna has been incorporated in a high-speed wireless LAN PC card system.

Set of new compact antennas suitable for integration on PCB

A novel compact antenna design is presented in this paper which is well suited for direct integration on the printed circuit board for a wide range of applications. In order to describe the concept four antenna structures scaled for operation at 433 MHz, 868 MHz, 1600 MHz and 2450 MHz is presented in this paper. In addition to the ease of integration, this type of structure exhibits a multi band frequency response with excellent radiation pattern stability over the different frequency bands.

Double frequency printed antennas for multi-mode communication application

The paper considers a new class of small size, single substrate layer, double frequency printed antennas for multi-mode PC card systems. A 2.4/5 GHz fabricated antenna exhibits a matching of 16 dB and 5 dB and a gain of 5 dB and 3 dB, respectively. On the other hand a 17.4/23.4 GHz fabricated antenna presents a matching of, respectively, 16 dB and 12 dB and a gain of 5.1 dB and 4.7 dB.

Metallic photonic band-gap materials (MPBG) as angular selective reflector or radome: application to antenna grating lobe reduction

This paper presents numerical and experimental results on metallic photonic band-gap materials (mpbg), composed of metallic wires and used as antenna reflector or radome. Attention is focused on mpbg angular response. In fact, with specified angular characteristics, MPBG materials can be interesting in order to reduce antenna grating lobes. One possible grating lobe reduction solution is based on the use of mpbg as angular filter. The radiation characteristics obtained with this solution are then improved by using a mpbg reflector to enhance the gain. Regarded to a classical metallic reflector, 20 dB and 12 dB gain improvement in the theoretical and in the experimental cases are respectively obtained, when the reflector is composed of more than two layers. The scanning performances are also presented. We show that angular filtering characteristics can be improved either by changing the array interface or by changing the mpbg lattice. In order to select the structure with the best angular behavior, an experimental and numerical characterization method is also presented.RésuméCet article présente les résultats numériques et expérimentaux sur les matériaux à bande interdite photonique métallique (bipm), composés de fils et utilisés en tant que réflecteur ou radôme. L’attention est particulièrement portée sur la réponse angulaire des bipm. En effet, certains comportements angulaires peuvent se révéler très intéressant pour réduire les lobes de réseau des antennes. Une méthode consiste notamment à utiliser un bip comme filtre angulaire. Les caractéristiques de rayonnement ainsi obtenues peuvent encore être améliorées grâce à l’utilisation d’un réflecteur bip. Ceci permet notamment d’augmenter le gain par rapport au cas d’un simple réflecteur métallique. L’augmentation est respectivement de 20 dB et 12 dB théoriquement et pratiquement, quand le réflecteur est composé d’au moins deux couches. Les performances de balayage de telles structures sont aussi présentées. Les auteurs montrent qu ’un changement du type de réseau permet d’améliorer le comportement angulaire de l’antenne tout en conservant une bonne réjection des lobes de réseau.