2D electronics based on graphene field effect transistors: tutorial for modelling and simulation

This paper provides modeling and simulation insights into field-effect transistors based on graphene (GFET), focusing on the devices’ architecture with regards to the position of the gate (top-gated graphene transistors, back-gated graphene transistors, and top-/back-gated graphene transistors), substrate (silicon, silicon carbide, and quartz/glass), and the graphene growth (CVD, CVD on SiC, and mechanical exfoliation). These aspects are explored and discussed in order to facilitate the selection of the appropriate topology for system-level design, based on the most common topologies. Since most of the GFET models reported in the literature are complex and hard to understand, a model of a GFET was implemented and made available in MATLAB, Verilog in Cadence, and VHDL-AMS in Simplorer—useful tools for circuit designers with different backgrounds. A tutorial is presented, enabling the researchers to easily implement the model to predict the performance of their devices. In short, this paper aims to provide the initial knowledge and tools for researchers willing to use GFETs in their designs at the system level, who are looking to implement an initial setup that allows the inclusion of the performance of GFETs.This research was funded by PTDC/EEI-TEL/29670/2017—(POCI-01-0145-FEDER-029670); co-financed by the European Regional Development Fund (ERDF), and through COMPETE 2020, by grant SFRH/BD/137529/2018

Study and Design of Reconfigurable Wireless and Radio- Frequency Components Based on RF MEMS for Low-Power Applications

This chapter intends to deal with the challenging field of communication systems known as reconfigurable radio-frequency systems. Mainly, it will present and analyze the design of different reconfigurable components based on radio-frequency microelectromechanical systems (RF MEMS) for different applications. This chapter will start with the description of the attractive properties that RF MEMS structures offer, giving flexibility in the RF systems design, and how these properties may be used for the design of reconfigurable RF MEMS-based devices. Then, the chapter will discuss the design, modeling, and simulation of reconfigurable components based on both theoretical modeling and well-known electromagnetic computing tools such as ADS, CST-MWS, and HFSS to evaluate the performance of such devices. Finally, the chapter will deal with the design and performance assessment of RF MEMS-based devices. Non-radiating devices, such as phase shifter and resonators, which are very important components in the hardware RF boards, will be addressed. Also, three types of frequency reconfigurable antennas, for the three different applications (radar, satellite, and wireless communication), will be proposed and evaluated. From this study, based on theoretical design and electromagnetic computing evaluation, it has been shown that RF MEMS-based devices can be an enabling solution in the design of the multiband reconfigurable radio-frequency devices

Metamaterial vivaldi antenna array for breast cancer detection

The objective of this work is the design and validation of a directional Vivaldi antenna to detect tumor cells’ electromagnetic waves with a frequency of around 5 GHz. The proposed antenna is 33% smaller than a traditional Vivaldi antenna due to the use of metamaterials in its design. It has an excellent return loss of 25 dB at 5 GHz and adequate radiation characteristics as its gain is 6.2 dB at 5 GHz. The unit cell size of the proposed metamaterial is 0.058λ × 0.054λ at the operation frequency of 5 GHz. The proposed antenna was designed and optimized in CST microwave software, and the measured and simulated results were in good agreement. The experimental study demonstrates that an array composed with the presented antennas can detect the existence of tumors in a liquid breast phantom with positional accuracy through the analysis of the minimum amplitude of Sii.FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/202

Electromagnetic study of the breast for biomedical applications

This work presents an electromagnetic test of the breast for biomedical applications. The test is given in the Industrial Scientific Medical (ISM) band where the frequency equal to 2.4 GHz. The simulation results of the electromagnetic aspects of the proposed test are given by Computer Simulation Technology Microwave Studio (CST-MWS) based on finite integration technique (FIT) method. The treated parameter for the immunity test of the breast is the Specific Absorption Rate (SAR). We propose four models of the breast phantom to obtain a comparative study in terms of the size effect and the thickness of different layers. The simulation results show that the immunity of the breast is depends to the Power energy and the breast size

Breast cancer detection based on CPW antenna

This work presents the design of CPW antenna for microwave tumor cell detection. The simulation results of the antenna performance in free space using CST-MWS are shown at 4.5 GHz. In order to study, the influence of the antenna movement on its electrical properties during breast cancer diagnosis, the CPW antenna is placed at a distance of 32 mm from the surface of the breast phantom with and without tumor cells by using different positions of the antenna to cover the entire breast surface and with various cross sections of the breast phantom. The tumor is represented by the sphere of diameter equal to 10 mm. In this paper, three interesting antenna parameters are analyzed, the return loss, the radiation pattern and the E-field inside the breast. This study shows good results to can detect the incidence of the tumor at 4 GHz. Comparing these results without and with tumor, it can be said that increasing the angle between the antenna and the breast phantom (from 0° to 60°), the return loss increases from -17 dB to -19.34 dB in 0°, from -15.37 dB to -19.28 dB in 30° and from -12.18 dB to -15.44 dB in 60°. The gain increases from 4.22 dB to 4.26 dB in 0°, from 1.13 dB to 1.2 dB in 30° and from 3.91 dB to 4.06 dB in 60°. In addition, to the increase of the e-field values inside the different cross sections of the breast phantom.(undefined

Modelling, design and fabrication of a novel reconfigurable ultra-wide-band impedance matching based on RF MEMS technology

This study proposes an adaptive impedance-matching network with tremendously reduced dimensions and presents its fabrication process. The proposed radio-frequency micro-electromechanical system (RF MEMS) device is based on a coplanar waveguide design and relies on suspended bridges for impedance tuning. The tuning is controlled by a variable applied DC voltage to the bridges. Preliminary tests validate the device's operation mechanism, and simulations were performed on both the mechanical aspects of the device (bridge gap manipulation) and tuning capabilities. This device presents the possibility of operating in a wide band of frequencies, namely [1-6] GHz, and for load impedances in the interval of [30-90] omega for the real part and [-10-30] for the imaginary part. The device's resonant frequency and its bandwidth can be modified easily by changing the bridge gap in the RF MEMS.This work was supported by the Laboratory of Circuit and Electronic System in High Frequency of University of Tunis El Manar and Research Center for Microelectromechanical Systems (CMEMS) of the University of Minho Braga, Portugal. Foundation for Science and Technology (FCT) project PTDC/EEI-TEL/5250/2014, by FEDER funds through POCI-01-145-FEDER-16695 and Projecto 3599-Promover a Produção Científica e Desenvolvimento Tecnológico e a Constituição de RedesTemáticas, and by grant SFRH/BD/116554/2016

Design of biomedical passive RFID tag antenna

This work is devoted to the study and design of passive RFID tag antenna, this tag can be used in biomedical applications; Essentially for detection of the patient’s condition in a hospital. This study based on the electromagnetic simulation results, the proposed test is given by Computer Simulation Technology Microwave Studio (CST-MWS) based on finite integration technique (FIT) method. We propose a dipole tag antenna in the 2.4-2.48 GHz Industrial Scientific Medical (ISM) band that’s meant to be incorporated in a wristband of a patient. The wristband antenna in free space has a good results in terms of S11 (-33dB), gain (2.73dB), directivity (2.89dBi), bandwidth (5.3%) and efficiency (97%). In order to study the effect of the human body on the performance of the antenna, this wristband will be placed on a phantom arm. Despite the high losses introduced by the human tissue, the antenna shows a good S11 (-17.8dB), gain (1.31dB), directivity (4.06dBi), bandwidth (5.7%) and efficiency (49%)