Ammar Kouki

École de Technologie Supérieure · Département de génie électrique

Dielectric and conducting liquids with varying electromagnetic properties can offer novel alternatives for building tunable microwave passive components as well as antennas. Injecting these fluidics in or around microwave substrates alters their overall electrical characteristics, enabling circuit reconfigurability. Alternatively, changing the shap...

In this letter, the second source harmonic in continuous-mode class GF (CCGF) is optimized to flatten the power amplifier's (PA) frequency response over a wideband. A new design space is explored by considering the effects of controlling the input nonlinearity of the gate-source capacitance ( $C_{{gs}}$ ) on the drain current waveforms under cont...

This paper proposes a methodology for the fast translation of ideal lumped-element values to the form of a 3D physical layout using low-temperature co-fired ceramic (LTCC) dielectric. It is explained how this approach is implemented without requiring complex formulas and use a simulation-based process which leads to consume less optimization/tuning...

A millimeter-wave dielectric resonator antenna array with an integrated feeding network and a novel alignment superstrate in Low Temperature Cofired Ceramics (LTCC) technology is presented. The antenna array consists of 16 cylindrical DR antenna (CDRA) elements operating at 28 GHz for mm-Wave 5G applications. The array is fed by an inverted microst...

In this article, a continuous-mode inverse class GF (CCGF <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> ) power amplifier is introduced based on a new closed-form expression for the drain current. This analytical expression is utilized to exploit second source harmonic impedance manipulation...

This paper investigates the optimal design permitting to recover thermal heat released from electronic power components mounted on ceramic substrates. Accordingly, the methodology and the characterization of thick-film/Low-Temperature Co-fired Ceramic (LTCC)-based multilayer thermo-electric micro-generators (TEGs) fabrication were detailed. Hence,...

Thirty‐nine years of archived meteorological data measured at two stations located in the northern and southern parts of Quebec, Canada are used to estimate the surface refractivity and its dry and wet components. The results of the comparison of the obtained estimates showed that for all months the values of the dry component are higher in the nor...

For the aim of surface refractivity analysis, the overall territory of Quebec has been divided in a desired number of areas from North to South using clustering analysis. The meteorological data used in the analysis are collected from 50 stations located in various climatic regions over Quebec for the year 2013. It is found that the best input data...

This article presents a frequency reconfigurable RF impedance tuner using eight cascaded fluidic cells to cover the frequency band [0.9, 2.4] GHz. The tuner is made of eight fluidic fillable cavities on top of a coplanar waveguide transmission line in a single low-temperature cofired ceramic (LTCC) substrate. Each cavity is either kept empty or fil...

In this paper, local meteorological data of one year have been used to calculate the surface atmospheric radio refractivity (N) and estimate the vertical refractivity gradient (dN 1) as well as the geoclimatic factor (K) in the lowest atmospheric layer above the ground surface in the station Kuujjuaq (Quebec, Canada). In this region, the climate is...

A novel, low complexity approach for the analysis of nonuniform lossy substrate‐integrated waveguide transmission lines based on the method of moments is proposed. The approach uses frequency‐dependent basis functions derived from the structure's propagation characteristics. Two tapered structures are analyzed, fabricated, and measured to validate...

The loop-gap resonator (LGR) was originally developed to provide a uniform microwave magnetic field on a sample for electron spin resonance (ESR) experiments. The LGR is composed of one or more loops and gaps acting as inductances and capacitances respectively. Typical LGR designs produce a uniform field on a sample at a single resonant frequency,...

The loop-gap resonator (LGR) was originally developed to provide a uniform microwave magnetic field on a sample for electron spin resonance (ESR) experiments. The LGR is composed of one or more loops and gaps acting as inductances and capacitances respectively. Typical LGR designs produce a uniform field on a sample at a single resonant frequency,...

In this paper, local meteorological data for a period of 35 years (from 1979 to 2013) from Kuujuaq station have been used to calculate the surface refractivity, N (a link for the data is available in the acknowledgements), and to estimate the vertical refractivity gradient, dN1, in the lowest atmospheric layer above the ground. Monthly and yearly v...

This paper presents the design optimization of thermoelectric generators (TEGs) based on low temperature co-fired ceramic (LTCC) technology. Three designs, containing 45 Ag/Ni thermocouples each, were studied: two conventional designs (π-type and Y-type TEGs) and one newly proposed design. The optimization was carried out to improve the temperature...

A new lumped-element circuit model suitable for dual-band bandpass filter (D-BPF) response is proposed. Using even-/odd-mode analysis, analytical equations are developed and used for the development of a direct synthesis design procedure. The proposed procedure is applied to the design and realization of a D-BPF prototype in low-temperature cofired...

The effects of high-rise buildings on satellite propagation in the vicinity of urban canyons are investigated. A comparison between a conventional canyon model (CCM) and two modified canyon models (MCMs), which take into account the presence of high-rise buildings, is presented for both narrow-band and wide-band signal cases. The narrow-band is dev...

A new vertical guiding structure in low-temperature cofired ceramics (LTCC) substrates is proposed. This vertical LTCC integrated waveguide (V-LIW) allows transmitting signals and realizing components in the body of the LTCC substrate perpendicular to its surface. This vertical integration leads to considerable footprint reduction while opening the...

In this work, we show that a stub‐loaded open‐loop double resonator filter can produce three transmission zeros at finite frequencies close to the passband when designed using our proposed asymmetric feed point topology. We demonstrate that by selecting the length of the stub, the placement of double transmission zeros on either the high side of th...

This paper presents conversion rules between X-parameters, linearized impedance parameters, linearized admittance parameters, linearized cascade parameters, linearized scattering transfer parameters, linearized hybrid parameters, and linearized inverse hybrid parameters of a two-port network under large-signal operating conditions. The rules have b...

This paper introduces new analytical expressions that relate between voltage and current of a nonlinear two-port network. These formulas are defined and derived, analytically, from ${X}$ -parameters. They are also extension of the well-known linear two-port network parameters. These formulations are defined as follows. Linearized impedance paramet...

The mechanical vibration of metal structures has a great effect on Low Frequency (LF) Radio Frequency Identification (RFID). The return signal link established from the tag to the reader is affected by induced current caused by magnetic coupling. The interference affects the performance of the RFID reader by distorting the binary information transm...

The main purpose of this paper is to convert the heat released by a heat source into electrical energy. In this aim, we intend to fabricate a thermoelectric generator based on LTCC technology. We will discuss, then, the different stages of the generator's fabrication. Also, we will study the electrical output parameters of three different generator...

This paper presents in detail the extension of the T - Ω formulation for eddy currents based on higher-order hierarchical basis functions so that it can automatically deal with conductors of arbitrary topology. To this aim, we supplement the classical hierarchical basis functions with nonlocal basis functions spanning the first de Rham cohomology g...

This paper proposes a novel design process of a piezoelectric micromachined ultrasonic transducer (PMUT) for achieving the best operating performance. The electromechanical coupling coefficient (EMCC) k² for thin-film piezoelectric devices defining PMUT performance was investigated analytically for design optimization. A unimorph PMUT disk formed b...

Fast frequency sweep using model order reduction (MORe) techniques is one of the most valuable and efficient features in high-frequency simulators. These techniques usually use a single full solution at a given frequency to build a smaller approximation reduced model, which might be insufficient for wideband and ultrawideband simulations of high qu...

Freestanding nanostructures play an important role in optical and mechanical devices for classical and quantum applications. Here, we use reactive ion beam angled etching to fabricate optical resonators in bulk polycrystalline and single crystal diamond. Reported quality factors are approximately 30 000 and 286 000, respectively. The devices show u...

This paper extends the $T$-$\Omega$ formulation for eddy currents based on higher order hierarchical basis functions so that it can deal with conductors of arbitrary topology. To this aim we supplement the classical hierarchical basis functions with non-local basis functions spanning the first de Rham cohomology group of the insulating region. Such...

A new architecture of multi-standard transmitter that combines single and double frequency conversion is presented. The transmitter is able to generate waveforms of different cellular standards (GSM, UMTS, Wimax), LAN standards (Bluetooth, Zigbee, IEEE802.11 b/g) and Radio navigation standards (GPS, Galileo) as well. Depending on the selected stand...

In this paper, we aim to analyze the gain ratio in the output induced voltage of a CMOS-compatible miniaturized electrodynamic microphone which is based on the use of two coplanar concentric inductors. These latter are comparable to a concentric transformer with a secondary situated on the microphone diaphragm top. The study has been applied when t...

An Empty LTCC (Low Temperature Cofired Ceramics) Integrated Waveguide (E-LIW) for the 57-64 GHz band is proposed. In addition to being air-filled, this SIW-like structure uses long rectangular side-wall vias to reduce conductor and radiation losses. In simulation, the proposed structure shows an insertion loss of 0.084 dB/cm at 60 GHz compared to 0...

This paper presents a new design technique and analysis for a microstrip Rotman lens which is feeding a wide bandwidth series-fed microstrip patch antenna array. In the proposed Rotman lens method, the length of the transmission lines does not affect the progressive phase delay. This reduces the complexity of the design and improves the performance...

Ray tracing simulation results indicate that a high-resolution database is not needed to exploit user position knowledge in the 28 GHz band, even in the case of inexact information. A proposed antenna alignment algorithm (using maximum position errors and database resolutions of 10 m and 4 m, respectively) that takes advantage of the propagation ch...

In this paper, a new accurate small-and large-signal equivalent-circuit-based modeling technique for gallium nitride (GaN) HEMT transistors grown on silicon substrate is presented. Despite X-parameters are developed as tools for the development of black-box modeling, they are used for equivalent-circuit-based model extraction. Unlike traditional mo...

This paper presents a deterministic propagation model to predict the path loss in urban environments specifically in high-rise building areas. The simulation results including narrowband and wideband channel simulation of path loss and normalized signal level in urban model are compared to the conventional line of sight (LOS) model. The significant...

A wide-band wide-scan phased array is investigated by utilizing the beamforming network that is based on a microstrip Rotman lens. A wide beam scanning capability of ±40° for the frequency range 8–12 GHz is demonstrated. The most crucial part is to design a wide beam scanning rotman lens in conjunction-with a good impedance matching over the entire...

In this study, three different parameter extraction approaches for GaN high electron mobility transistors are presented and evaluated. The first approach depends on only cold pinch-off measurements, the second approach based on cold pinch-off and forward measurements and the last one uses de-embedding open structure in addition to unbiased cold mea...

Low temperature co-fired ceramic (LTCC) based microfluidic sensors have been developed for biomedical and environmental sensing systems. This paper introduces a microfluidic chamber based on impedance spectroscopy measurements using LTCC technology for wireless Lab-On-A-Chip (LOC) applications. To overcome the channel sagging during the fabrication...

Microelectromechanical Systems (MEMS) are often used in transceiver modules, especially for telecommunication and radar applications. In this paper, we present recent progress in the development on a MEMS-on-LTCC process. We focus on the Low Temperature Co-fired Ceramic (LTCC) substrate issues and we present a successful solution for overcoming the...

The wireless telecommunication systems have an undeniable role in today's society. The rapid progress of wireless services and applications accelerates demands for high data-rate reliable systems. The 60 GHz band with its 5 GHz globally unlicensed available spectrum, provides a great opportunity for the next generation of high data-rate wireless co...

This work presents the design and fabrication of a wideband dual polarized patch antenna to be used in an array for applications such as satellite communication. Our proposed patch is made of 591 Green Tape made by Low Temperature Co-Fired Ceramic and Rogers RT5870, and is designed to work in the frequency range of 10.7–12.7 GHz. Our result shows t...

Simulation data from a ray-tracing tool applied in specific urban environments in the 28-GHz band suggest that the utilization of arbitrary base station (BS) angles in a directional search procedure may not be of maximum benefit for users located in non-line-of-sight positions, because certain angles restrict the radio frequency illumination to a l...

Unlike digital designs where very complex circuits can be designed with minimal designer worries about the details of the physical technology, RF circuit and systems designs and techniques have seen very little evolution over the years and remain largely manual requiring extensive user intervention and considerable expertise. While digital hardware...

Implantable medical devices have been implemented to provide treatment and to assess in vivo physiological information in humans as well as animal models for medical diagnosis and prognosis, therapeutic applications and biological science studies. The advances of micro/nanotechnology dovetailed with novel biomaterials have further enhanced biocompa...

In this paper, a nonlinear modeling approach for gallium nitride high-electron mobility transistor (GaN HEMT) on Si substrate is proposed. A reliable method has been developed to extract the extrinsic elements of the model. Its main advantage is its accuracy and dependency on only pinched-off and unbiased S-parameter measurements. The extrinsic ele...

Fast frequency sweep using Model Order Reduction (MORe) techniques is one of the most important features in modern FEM-based simulation software. In fact MORe techniques, and the Well-Conditioned Asymptotic Waveform Evaluation (WCAWE) technique in particular, reduce considerably the simulation time by providing accurate S-parameter approximations o...

This chapter presents advances in automating RF design through the adoption of a framework that tackles primarily the issues of automation, complexity reduction, and design collaboration. The proposed framework consists of a design cycle along with a comprehensive RF hardware abstraction strategy. Being a model-centric framework, it captures each R...

This paper discusses the mechanical vibration effect of metal structure on RFID and presents a solution to circumvent it. The transmission link between a tag and RFID reader is affected by induced current issued from magnetic coupling. This interference affects mainly the performances of the RFID reader. A new practical technique that avoids the re...

This paper presents experimental results of overwater radio path loss in the 4.4 to 5.0 GHz band. These measurements involve horizontal and vertical polarizations. Based on electromagnetic theory, a deterministic two ray model that mimics measurements is developed. The model can predict the received power level for all distances lower and higher th...

Conference Paper in the IEEE Wireless and Microwave Technology Conference, Cocoa Beach, Florida, USA, April 2015.

Conference Paper in the IEEE Wireless and Microwave Technology Conference, Cocoa Beach, Florida, USA, April 2015.

This paper proposes a new filter’s design process and modeling that can be employed in RF wireless communication systems. The filter is constructed by two similar rectangular piezoelectric plates vibrating in the width-extensional mode. Each plate is formed by a piezoelectric film and is sandwiched between two metallic electrodes. The vibrating pla...

Many factors could be considered to produce spectral regrowth in communications systems as well as the nonlinearity of power amplifiers. This paper proposes a novel reduced complexity dual band power amplifier (PA) digital predistortion. A new approach that is based on orthogonal polynomials is presented to overcome the limits of the nonlinear comp...

Heart failure afflicts the developed world, causing mortality more than any other diseases. This is due to the fact that humans' heart possesses a very limited capacity to regenerate. Heart attacks or myocardial infarction (MI) could result in an irreversible loss of cardiomyocytes and consequently heart failure. Besides, zebrafish and neonatal mic...

In this paper a reliable and cost-effective modeling approach for GaN HEMT on both Si and SiC substrates is presented. The developed model is validated in terms of small-and large-signal simulations for 2-mm GaN-on-Si and 1-mm GaN-on-SiC HEMTs.

This paper discusses the mechanical vibration effect of metal structure on RFID and presents a solution to circumvent it. The transmission link between a tag and RFID reader is affected by induced current issued from magnetic coupling. This interference affects mainly the performances of the RFID reader. A new practical technique that avoids the re...

A new parasitic elements extraction technique for GaN HEMT transistors on Si substrate is presented. This technique is based on the use of two de-embedding GaN structures: open and thru-short. The equivalent circuit models along with the extraction procedure are detailed. A very good agreement between measurements and simulations validate the devel...

Novel techniques to increase the self-resonant frequency (SRF) of parallel plate capacitors and toroid inductors are presented. A new capacitor interconnection technique is proposed and shows 23% increase in SRF. Judiciously placed air cavities are proposed for toroid inductors and lead to a 22% increase in SRF. All inductors and capacitors are des...

New architecture for a compact dual-band coupler filter suitable for avionic systems operating in the VHF 108-137 MHz and UHF 329-335-MHz bands is proposed. A systematic design methodology is presented, whereby, starting with a distributed branchline coupler, equivalent lumped-element models are generated and augmented to obtain the desired functio...

Monitoring of structural health plays a crucial role in condition-based maintenance and prediction of unsafe or damaged infrastructures. We have developed an interdigitated capacitive (IDC) strain sensor integrated in a wireless monitoring system that could be used for structural health monitoring (SHM). The 125-μm thin brass IDC sensors were fabri...

It is well known that the propagation of electromagnetic waves is affected by the refractivity of the atmosphere. This refractivity is characterized by the value of the radio refractive index, which depends on the temperature, pressure, and humidity in the atmosphere. In this paper, we estimate the radio refractive index (N), the point refractivity...

A new architecture for a compact dual-band coupler suitable for avionic systems operating in the VHF and UHF bands is proposed. The structure is implemented using lumped inductor and capacitor elements. The required elements and their integration to form the dual band coupler are designed and fabricated in LTCC technology with very small form facto...

There is described a duplexer comprising: a dielectric substrate having a circuit-receiving surface and an opposite surface; a ground structure deposited on the circuit-receiving surface or the opposite surface; a first filter connectable to a first terminal and having a first frequency bandpass; a second filter connectable to a second terminal and...

This paper presents a signal processing block intended for a NARMA-based linearization of an RF power amplifier that exhibits a non-monotonic voltage response. This type of response may be obtained when applying a dynamic hardware reconfiguration of the amplifier for power efficiency improvement, through the activation or deactivation of sections i...

Different kinds of RF power combiner are studied. Wilkinson and hybrid combiner show very good linearity but low power efficiency. Chireix combiner using stubs at the input shows good efficiency and bad linearity of system. This paper shows that an unmatched chireix combiner without stub used at the output of class-B amplifiers can be optimized in...

Microwave telecommunications links are severely influenced by the frequency and climatic parameters as refractivity gradient (dN1), geoclimatic factor (K), rain, temperature, pressure, and humidity. This influence increases with the frequency of the wave. In microwave band, recent research has shown that the geoclimatic factor (K), rain and tempera...

AbstractA wideband circularly polarized single‐patch single probe‐fed patch antenna is investigated for applications of GPS L5, L2 and Galileo E5a, E5b bands. The wideband circular polarization (CP) is achieved by corner‐truncated square patch and insertion of a thick air layer between the radiating patch and the ground plane. A conducting circular...

An analytical design methodology of outphasing amplification systems is proposed using new simplified analytical expressions for the instantaneous efficiency and the input/output voltages of Chireix outphasing combiners. These expressions are derived first for ideal voltage sources with nonzero internal impedance and later for ideal Class-B amplifi...

A new system level architecture for multi-standard receivers to cover all the VHF and UHF band avionic systems is proposed. The proposed architecture relies on special RF front-end filtering to separate different services. A dual band-pass filter is designed using only two resonators. The resonators are designed and fabricated in LTCC technology us...