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 S_ii.

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.

Objectives: This work is devoted to the study and design of a small and flexible CPW patch antenna (26x30x0.64) mm3 for microwave tumor detection. Methods : The suggested flexible CPW antenna for breast cancer detection is made with a Rogers RO 3010 substrate (0.64 mm thickness). The simulation was carried out using HFSS software and the experimental validation was done with liquid phantoms which have the same EM characteristics of breast and tumor. Two tumor phantoms of different sizes, 8 and 15 mm, were tested. Two scenarios for breast cancer detection are proposed. In the first scenario, the proposed CPW antenna is used only as a receiver of the RF signal traveling through the breast. In the second scenario, two CPW antennas are used, one as a transmitter and the other as a receiver. Findings: Both the simulation and experimental results in free space of the antenna performance show that the resonance frequency of the proposed antenna is around 4.5 GHz and there is a good agreement between the simulated and experimental results. In addition, the proposed antenna has a gain of 2 dB at the desired frequency. The achieved radiation efficiency of the antenna is 86%. The comparative study of the transmission coefficient (S12) in the two scenarios yielded almost the same results, and the tumor detection was demonstrated at the frequency of 2.95 GHz with both tumor sizes (without tumors: S12 =-43.72 dB; with tumors: S12 =-55.36dB for the 15 mm tumor and S12 =-48.36 dB for the 8 mm one). Novelty: The proposed CPW antenna is useful as a sensor for tumor detection because of its relatively high radiation efficiency, flexible and small size. Keywords: Microwave imaging; breast cancer detection; tumor; CPW antenna; Phantom

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.

This paper presents a new monolithic microwave integrated circuit (MMIC) based on coplanar waveguide (CPW) design for a tunable resonator based on RF MEMS. This RF structure, which can be used for system on chip (SOC), is constituted with MEMS Bridge placed between two meander inductors and the tenability is controlled by a variable applied DC voltage. Moreover, this device presents a compactness characteristic and the possibility to operate at high frequencies. The resonant frequency and the bandwidth can be changed easily by changing the bridge gap of the RF MEMS. The numerical simulations of this novel structure of a tunable RF MEMS resonator were performed with the electromagnetic solvers CST MWS (Computer simulation Technology Microwave Studio) and validated by the more accurate electromagnetic solver HFSS (High Frequency Structural Simulator). The simulation results, for three different spacing of the bridge gap, show that the tunable frequency band are between 10 and 40 GHz with the two electromagnetic solvers and exhibiting three resonant frequencies (21, 23.1 and 24.6 GHz).The simulation results of the return loss using CST achieves 29 dB with an insertion loss less than 1 dB; However, the HFSS simulation shows similar performance in the resonant frequencies and in the bandwidth giving better results in terms of the return loss (about 35dB instead of 29 dB) and showing a good adaptation.