We are always interested in solving problems that engineers in industry could face. However, as regard to our planned research, we are currently working on the following research tasks:

EM-Based CAD Tools for RF/Microwave Circuit Modelling and Design
Any RF/microwave circuit simulated response, like gain or dispersion, depends closely on how the implemented miniaturized components are modeled. To be efficient, this aspect requires the resolution of several EM issues related to the complexity of the integrated structure due to the hybrid nature of the EM field. Strip thickness, finite conductivity, and number of layers, are factors that can significantly affect the propagation and attenuation characteristics of EM field in high-density multilayered hybrid/monolithic MICs. Such characteristics have been widely investigated using various techniques like the perturbation technique, the mode-matching method, and the method of lines. However, the perturbation approach is not suitable for MICs since the skin depth and the strip thickness are in the same order, while the above fullwave methods are CPU time consuming. Thus, easier and faster methods need to be developed to meet the evolution of MICs.
Our team has developed various EM numerical tools using the spectral domain method through the derivation of dyadic admittance Green’s functions via a recursive process, which significantly enhances the CPU time.

EM-Based CAD Tools for RF/Microwave Circuit Simulators
Another key aspect to be considered in MIC design is the parasitic coupling. Coupling is becoming more of a concern in MICs as packing densities of devices are increased and frequencies are pushed higher. Although such coupling plays an important role in circuit performance, this quantity is very complex to evaluate and several numerical techniques in bringing this forward into circuit design space have been investigated. Mainly based on the resolution of Maxwell’s equations, such EM methods have demonstrated their efficiency, but still require huge computation time and memory space. This aspect is crucial when modern design tools lead to massive and highly repetitive computational tasks during simulation, optimization and statistical analysis. Furthermore, recent lumped EM-based models seem to be helpful in obtaining a quick initial design, but they are developed under perfectly shielded conditions excluding parasitic coupling between neighbouring components, and hence, they tend to be inefficient for circuit-level simulation.
In this topic, our team has proposed a novel technique for computation of EM parasitic coupling in passive structures based on simple circuit theory and de-embedding concepts.

Compact Transistor Models For RF/Microwave Circuit Design
Since Field Effect (FETs) and Heterojunction Bipolar Transistors (HBTs) are widely used in the RF/microwave range, a large number of modelling approaches are being proposed. Detailed physics-based transistor models are accurate, but slow. Table look-up models can be fast, but suffer from the disadvantages of large memory requirements and limitations on number of parameters. Nevertheless, they are difficult to develop, equivalent circuit models remain the most common modelling approach, where the element values can be determined either by direct extraction or by optimization-based extraction. Fast and simple to implement, direct-extraction techniques provide adequate values for the more dominant circuit elements, but they cannot determine all the extrinsic elements uniquely. On the other side, optimization-based extraction techniques are more accurate but computationally intensive and relatively sensitive to the choice of starting values. Furthermore, to make them attractive to non-experienced users, such extraction techniques often assume a prior universal circuit topology referred as the FET standard topology or the HBT standard topology.
Determining the most suitable small-signal equivalent circuit configuration (topology) and accurately extracting its element values was the preliminarily target of our team. Based on an exhaustive literature review, a circuit library has been created that contains the most widely used topologies. Thus, by combining the Fuzzy c-means method and neural network capabilities, a method was developed that efficiently selects the most suitable small-signal circuit topology for a given set of measured S-parameters. The goal is to extend this generic approach to generate nonlinear/thermal FET and HBT models. In fact, many roadmaps now recognize advanced nonlinear and thermal analyses as two of the major challenges in electronic product innovation due to ongoing push of technology towards higher power and complexity, and reduced size.

Advanced Tools for RF/Microwave Antenna Design
Our team has demonstrated its know-how in antenna design. We completed successful contracts for the Defence Research and Development Canada (DRDC) on the topic of designing planar antennas for ultra wideband (UWB) applications, especially for direction finding systems. We developed an innovative technique for UWB (2-18GHz) sinuous planar antenna design and balun integration, along with original non-uniform tapered UWB couplers for the sinuous antenna feed.
Furthermore, we designed new kinds of very sensitive and highly miniaturized dosimetric probes for accurate measurements of EM radiation effects on the human body. Such probes will enhance the knowledge of EM radiation effects of cellular phones, microwave ovens and other daily RF equipment on human health.

RFID
Design of Passive and active RFIDs, Miniature antenna design for RFID tags, Wireless sensor networks.