Ahmad Bilal

This paper presents a method of introducing novel bar shaped multiple patches to enhance the gain of the often-ignored North Atlantic Treaty Organization (NATO) radio frequencies E-band, that is from 2–3 GHz while maintaining high gain through the entire bandwidth of the antenna. The patches are introduced in the vicinity of the antenna flares. The length of the patches increases subsequently in the end fire direction to cater for different frequency fields. This approach improves the gain and directivity by field coupling, without getting a tradeoff with the absolute bandwidth of the antenna. This new antenna prototype has dimensions of 100 mm × 90 mm × 1.5 mm with measured gain from 3.8–7.8 dBi from 2–10 GHz and for NATO E-band the gain ranges from 3.8–5 dBi which is better than the previous designs with respective antenna size.

The amyloid- beta (Aβ) protein is a peptide that plays a central role in the development and progression of Alzheimer's disease, originating from the cleavage of the amyloid precursor protein (APP). The peptide's structural variability is linked to different stages and manifestations of Alzheimer's pathology, making it a critical focus for understanding the disease. Current therapeutic strategies primarily involve pharmacological interventions, but they have met with limited success in altering the course of the disease. Our research introduces an innovative approach to address this challenge by employing electromagnetic waves, specifically at a frequency of 900 MHz We performed comprehensive electromagnetic simulations to explore the effects of this frequency on Aβ structures, aiming to offer an alternative non-invasive treatment avenue. Following these electromagnetic simulations, molecular dynamics (MD) simulations were carried out using the Large Scale Atomic/Molecular Massively Parallel Simulation (LAMMPS) software to further investigate the peptide’s response at the atomic and molecular level. These simulations provided insights into the structural dynamics of Aβ under electromagnetic influence, enabling a deeper understanding of the peptide’s behavior. To substantiate the findings from our simulations and the theoretical framework, we conducted a Thioflavin T (ThT) assay and western blot analysis on in vitro Aβ fibril samples which are treated with electromagnetic (EM) wave exposure using a TEM cell device. After 3 hours of EM wave exposure, a noticeable decrease in Aβ fibrils was observed. This experimental validation was essential in confirming the simulation results and reinforcing the theoretical basis of our approach. Together, simulations and experimental evidence provide a strong foundation for exploring electromagnetic-based treatments as a potential therapeutic intervention for Alzheimer’s disease.

This paper proposes a new method to find the optimum frequency offsets in a Frequency Diverse Array (FDA) radar transmit beampattern that minimizes the Peak Side Lobe Level (PSLL) and Half Power Beamwidth (HPBW). This method uses a modified Bayesian Optimization (BO) framework where Bayesian Neural Network (BNN) is used for surrogate modelling of FDA radar transmit beampattern objective function. By resampling the weights and biases of BNN, we get a distribution of predictions whose mean and standard deviation are used to compute the Expected Improvement (EI). A population of frequency offsets where the EI is higher is used to initialize Genetic Algorithm (GA). Unlike the traditional method of random initialization, this method guides GA, which in turn, searches and updates the BNN with function evaluations. Hence, each sub-optimal GA run trains the BNN, and this cycle is repeated until convergence. Simulation results show that this method yields PSLL and HPBW that are lower than state-of-the-art.

Beampattern of a frequency diverse array (FDA) is a function of time, range and angle. The shape of this beampattern is dependent on the frequency offsets (FO) that are applied to each element. These FO are sampled from a window function whose parameters are optimised to yield minimum peak side lobe level (PSLL) and half‐power beamwidth (HPBW). Time‐variance is usually ignored because it can be removed by signal processing at the receiver. However, the travelling beam is still time‐variant. This work shows that, in a time‐variant beampattern, the optimum PSLL of these window functions degrade while HPBW is unaffected. A window function that is based on a sum of three Sinc functions (s‐Sinc) is proposed for FO optimisation. The superiority of this window is established by comparing the optimum PSLL and HPBW in a time‐invariant scenario. Later, time‐variance is introduced, and s‐Sinc function is used to minimise time‐variant PSLL and HPBW. Results show that a beampattern with low time‐variant PSLL and HPBW can be synthesised compared to their time‐invariant counterparts.

This article demonstrates that the complex value of S₁₁ of an antenna, acquired in a multi-monostatic configuration, can be used for localization of a dielectric anomaly hidden inside a dielectric background medium when the antenna is placed close (~5 mm) to the geometry. It uses an Inverse Synthetic Aperture Radar (ISAR) imaging framework where data is acquired at multiple frequencies and look-angles. Initially, near-field scattering data are used for simulation to validate this methodology since the basic derivation of the Multiple Signal Classification (MUSIC) algorithm is based on the plain wave assumption. Later on, from an applications perspective, data acquisition is performed using an antipodal Vivaldi antenna that has eight constant-width slots on each arm. This antenna operates in a frequency range of 1 to 8.5 GHz and its S₁₁ is fed to the 2D MUSIC algorithm with spatial smoothing whereas the antenna artifact and background effect are removed by subtracting the average S₁₁ at each antenna location. Measurements reveal that this methodology gives accurate results with both homogeneous and inhomogeneous backgrounds because the size of data sub-arrays trades between the image noise and resolution, hence reducing the effect of inhomogeneity in the background. In addition to near-field ISAR imaging, this study can be used in the ongoing research on breast tumors and brain stroke detection, among others.