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This research focuses on the design and optimization of a graphene-based microwave ablation applicator (MWA) for tumor treatment. The unique properties of graphene, such as high impedance at microwave frequency and tunable Fermi energy, make it an ideal candidate for inducing charge carriers through an electric field or chemical doping. The study further employs machine learning techniques, including support vector regression (SVR) and artificial neural networks (ANN) to predict the ablation zone. The applicator design incorporates a helix antenna element connected to a coaxial cable working at 2.45 GHz with a graphene sheet and T-ring attached to the outer conductor. The challenge of achieving a zero-Fermi energy is addressed by introducing defects to increase surface resistivity, resulting in an impedance close to the required value. The results show that the graphene-based applicator enhances the ablation zone, leading to efficient and controlled tumor treatment. To predict the ablation zone accurately, the study employs machine learning techniques, including SVR and ANN utilizing Taguchi method to reduce computational complexity. Large and round ablation zone is achieved using novel applicator. Further, the performance metrics, including root-mean-squared error and coefficient of determination (R2), are utilized to evaluate the predictive capabilities of the model and found to be optimum. The research demonstrates the potential of graphene in improving MWA treatment and highlights the importance of machine learning in optimizing MWA and predicting treatment outcomes. [ABSTRACT FROM AUTHOR]

Summary: In this communication, a dual port printed multi‐input and multi‐output (MIMO) antenna with high isolation of dimension 12 × 8.5 × 0.8 mm3 is designed, analyzed, and investigated for 28‐GHz 5G mm‐wave applications. The metasurface layer is suspended over the MIMO antenna to convert the linearly polarized (LP) wave to a circularly polarized (CP) wave. The unit cell of the metasurface consists of a square‐shaped conducting strip with one side of diagonal points interconnected. The conducting strip and rectangular gap between the strips etched on the substrate are capable of generating the π/2 phase shifted electric field components (Ex and Ey) resulting in polarization conversion from LP to CP. The machine learning concept is used to characterize the dimensional configuration of the antenna to achieve the optimum throughput. The MIMO diversity performance parameters and antenna essential results are validated by the measured counterparts. [ABSTRACT FROM AUTHOR]

In this communication, a planar dual port multiple input multiple output antenna of size 1.2λ0 × 0.6λ0 × 0.008λ0 with LHCP/RHCP features is reported for the fifth-generation new radio n77/n78 sub-6 GHz wireless applications band. The single unit of the proposed design consists of a modified L-shape rectangular radiator with Z-shape slot loaded DGS. The defected ground structure is optimized through machine learning algorithms to achieve the maximum ARBW (output) by Right Shifting (RS) and left shifting (LS) the DGS and obtaining input features. The performance metric for ANN with ADAM optimizer was found to be optimal with MSE and R2 of 0.99 and 0.82, respectively. ANNs can leverage gradient information to guide the optimization process. This enables faster convergence towards optimal solutions compared to popular GAs and PSO, which are often gradient-free optimization methods. The MIMO configuration is achieved by creating a mirror image of the single unit about the x-axis. The salient features of the proposed design are (a) Impedance bandwidth (IBW) of 3.0–4.2 GHz covering the n77/n78 band, (b) 3-dB axial ratio bandwidth (ARBW) of the 2.6–3.9 GHz (c) Port-1 is generating RHCP while Port-2 is generating LHCP, results in polarization diversity. Different diversity performance parameters (ECC < 0.005, DG ~ 9.99 dB, and MEG < 3 dB) are in the optimum range confirming the proposed configuration as a suitable design for a MIMO radiator. [ABSTRACT FROM AUTHOR]

This work proposes a novel dielectric resonator antenna design for 5G-based IoT applications that operates in the sub-6 GHz frequency range. The DR antenna is built on a 1.6-mm-thick FR-4 substrate with dimensions of 30*50 mm2. The proposed dielectric resonator antenna is made of alumina and is excited using a microstrip feedline of 50 Ω. Because of the hybrid arrangement of cylindrical and rectangular dielectric resonator elements on the FR4 substrate, this proposed structure has improved the radiation mechanism. The antenna design process begins with creating the antenna in the Ansys HFSS EM simulator, which is then optimized using machine learning based on the antenna geometry's target factors. A data set of 2625 sample data values is generated in HFSS and fed to various machine learning algorithms for further optimization based on data trends. Post-optimization, the antenna design is fabricated and tested. The proposed antenna offers a wide bandwidth of 1.1 GHz between 3.5 and 4.6 GHz and resonates at 3.9 GHz making it suitable for 5G sub-6 GHz IoT applications. [ABSTRACT FROM AUTHOR]

In this communication, a planar dual port multiple input multiple output antenna of size 1.2λ0 × 0.6λ0 × 0.008λ0 with LHCP/RHCP features is reported for the fifth-generation new radio n77/n78 sub-6 GHz wireless applications band. The single unit of the proposed design consists of a modified L-shape rectangular radiator with Z-shape slot loaded DGS. The defected ground structure is optimized through machine learning algorithms to achieve the maximum ARBW (output) by Right Shifting (RS) and left shifting (LS) the DGS and obtaining input features. The performance metric for ANN with ADAM optimizer was found to be optimal with MSE and R2 of 0.99 and 0.82, respectively. ANNs can leverage gradient information to guide the optimization process. This enables faster convergence towards optimal solutions compared to popular GAs and PSO, which are often gradient-free optimization methods. The MIMO configuration is achieved by creating a mirror image of the single unit about the x-axis. The salient features of the proposed design are (a) Impedance bandwidth (IBW) of 3.0–4.2 GHz covering the n77/n78 band, (b) 3-dB axial ratio bandwidth (ARBW) of the 2.6–3.9 GHz (c) Port-1 is generating RHCP while Port-2 is generating LHCP, results in polarization diversity. Different diversity performance parameters (ECC < 0.005, DG ~ 9.99 dB, and MEG < 3 dB) are in the optimum range confirming the proposed configuration as a suitable design for a MIMO radiator. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma has been the leading cause of death in recent centuries and with the advent of newer technologies, several thermal and cryo‐ablation techniques have been introduced in the recent past. In this regard, microwave ablation has developed into a promising method for thermal ablation technique. However, due to clinical obligations, in‐vivo analysis is not feasible and ex‐vivo analysis is inaccurate due to changes in the electrical and thermal properties of the tissue. Therefore, in this study, temperature‐dependent permittivity, electrical conductivity, and thermal conductivity along with phase change effect due to temperature reaching above 100°C are incorporated using finite element method model. Further, using an intertwined normal mode helical antenna ablation probe, a change in resonant frequency (Δf) and reflection coefficient (ΔS11) from the actual value (antenna parameter in the air at 5 GHz) is modeled using second‐order polynomial curve fitting to predict the surrounding permittivity in the range of 30–70. A maximum deviation of 0.8 value in permittivity from the actual value is observed. However, to obtain a generalized methodology, XG Boost and CAT Boost algorithms are used. Further, since ablation diameter plays a crucial role in achieving optimal tumor ablation, an artificial neural network (ANN) algorithm with three different optimizers is incorporated to predict ablation diameter using five critical parameters. Such an ANN algorithm which can predict the transversal and axial ablation zone may provide optimal ablation outcomes. [ABSTRACT FROM AUTHOR]

Summary: A novel multiple‐input multiple‐output double asymmetrical cylindrical dielectric resonator antenna (MIMO‐DCDRA) with modified stub line feed is discussed and proposed in this work. Two unequal CDRA are placed diagonally to each other and are electromagnetically coupled with feeding arrangement via two asymmetrical circular apertures. By performing the optimization of the dimensional parameters, a significant impedance bandwidth of 70.84% ranging from 2.87 to 5.76 GHz and axial ratio bandwidth (ARBW) of 34.89% is obtained. Antenna gain is about 5.0 dBi within the operating frequency. The proposed MIMO‐DCDRA exhibits a low mutual coupling of (|S21| & |S12| < −20 dB) with the incorporation of a neutralization line. There are various diversity parameters that are also discussed in terms of mutual coupling, envelop correlation coefficient (ECC < 0.002), diversity gain (DG > 9.995), and channel capacity loss (CCL < 0.3 bits/s/Hz) over the entire impedance bandwidth. [ABSTRACT FROM AUTHOR]

Cancer is the leading cause of death in recent centuries and microwave ablation (MWA) has been evolving to thermally treat cancerous tissue through cell necrosis and is also a promising substitute to radio frequency ablation. In this article, a novel normal‐mode helical antenna based MWA probe is investigated for the effect on ablation diameter in the presence of five critical parameters. The antenna consists of an intertwining helix structure mounted on a very small ground plane. An external tapping is used to match the antenna impedance. In the proposed design at the center frequency, a reflection coefficient of more than 23 dB without insertion into the tissue model and a reflection coefficient of more than 14 dB with insertion into the tissue model have been observed at 5 GHz frequency. The gain and percentage bandwidth of the antenna is 0.6 dB and 10%, respectively. At 20 W power, a maximum ablation diameter of 32 mm (transversal‐T) and 44 mm (axial‐A) is reached within 5 min of application time at a distance of 30 mm from the probe. Further, the L27 Taguchi's orthogonal array has been employed to study the effect on ablation diameter by varying five thermo‐electrical parameters. The outcome of Taguchi's analysis has been ranked according to the contribution of each parameter. Further, F‐ and p‐value test has been employed using analysis of variance to study the significance of each parameter on ablation diameter. [ABSTRACT FROM AUTHOR]