This paper presents a single-layer antenna array with wideband circular polarization. The array is formed by 2 × 2 element antennas, each element including two radiators mutually coupled to each other and fed by a sequential feeding network. The antenna array is designed, fabricated and measured with overall size of $1.49\lambda \times 1.49\lambda$ at the center frequency of 28 GHz. The proposed antenna achieves the desired radiation patterns and provides excellent characteristics, including a wide bandwidth and compact structure. The results show a large bandwidth of 31.32% and a wide axial ratio of 20.2%, which is the largest found in the literature for similarly sized arrays on a single layer. Besides, the peak gain of 13.8 dBi is achieved over the operating frequency range. These merits confirm the proposed antenna design as a suitable choice for 5G communications.

Electronics is a field of study ubiquitous in our daily lives, since this discipline is undoubtedly the driving force behind developments in many other disciplines, such as telecommunications, automation, and computer science. Nowadays, electronics is becoming more and more widely applied in life science, thus leading to an increasing interest in bioelectronics that is a major segment of bioengineering. A bioelectronics application that has gained much attention in recent years is the use of sensors for biological samples, with emphasis given to biosensors performing broadband sensing of small-volume liquid samples. Within this context, this work aims at investigating a microfluidic sensor based on a broadband one-port coplanar interdigital capacitor (IDC). The microwave performance of the sensor loaded with lossless materials under test (MUTs) is achieved by using finite-element method (FEM) simulations carried out with Ansoft’s high frequency structure simulator (HFSS). The microfluidic channel for the MUT has a volume capacity of 0.054 μL. The FEM simulations show a resonance in the admittance that is reproduced with a five-lumped-element equivalent-circuit model. By changing the real part of the relative permittivity of the MUT up to 70, the corresponding variations in both the resonant frequency of the FEM simulations and the capacitance of the equivalent-circuit model are analyzed, thereby enabling assessment of the permittivity sensitivity of the studied IDC. Furthermore, it is shown that, although the proposed local equivalent-circuit model is able to mimic faithfully the FEM simulations locally around the resonance in the admittance, a higher number of circuit elements can achieve a better agreement between FEM and equivalent-circuit simulation over the entire broad frequency going range from 0.3 MHz to 35 GHz.

Microwave imaging had been around for some time in the research field of imaging technologies. Most researchers have focused on breast imaging and a few others on brain imaging. This article presents a review, a part feasibility study and proves of concept into the possibility of imaging the lungs in similar manner as the breast and brain. We present reviews of usage of microwave energy in various lung-heart related diseases, heart and breathe detector and lung tumour detection. The basis for tumour detection using microwave, various tumour and normal tissues compared were also reviewed. We aim to motivate researchers towards imaging the lungs using UWB microwave imaging methods.

A Vivaldi antenna for ultra-wideband application with complete dispersion analysis has been investigated in this work. By using a wideband microstrip-to-slot transition feeding mechanism, the antenna is excited. The measured return loss shows the antenna has an impedance bandwidth from 1.45 GHz to 5.35 GHz. An end-fire radiation pattern is achieved with a measured peak gain of 10.5 dBi at 4.5 GHz. Both time and frequency domain dispersion analysis of the proposed Vivaldi antenna are performed with experimental results. Measurement results indicate reasonable phase linearity with a measured group delay variation of almost 1 ns over its operating bandwidth that ensures dispersion-free characteristic of the proposed antenna. Moreover, transmitted and received ultrawideband time domain pulses of the proposed antenna have been experimentally validated to verify dispersion characteristics of the proposed antenna. The proposed antenna has a physical dimension of 19.5 cm ×14.5 cm×0.152 cm which can be easily integrated in a compact pulse-based ultra-wideband radar system.

Scattering parameters from a stratified model of the human thorax illuminated by ultra wideband pulses from an antenna is processed in an attempt to detect tumor. Difference of the scattering parameters recorded from the thorax model in the presence and absence of tumor was processed to generate an image showing the presence of a strong `scatterer' which correspond to the tumor. Tumor size of 10mm and antenna distance of 10mm from the model were considered. The results showed that the millimeter sized tumor can be detected. Filtering or smoothing was shown to give a better resolution of the images in the projection plane compared to without smoothing. Thus, it is evident from the images that smoothing enhances the plot quality for better lung tumor detection.

In this paper, polymer magneto-dielectric (PDMS-Fe ₃ O ₄ ) is proposed as a new substrate for multilayer microstrip antenna array for enhancement of bandwidth, gain, and overall efficiency. Nanoparticles of iron oxide (Fe ₃ O ₄ ) have been composited with polymer matrix of polydimethylsiloxane (PDMS) to build up the polymer magneto-dielectric layer (PDMS-Fe ₃ O ₄ ). Polymer magneto-dielectric (PDMS-Fe ₃ O ₄ ) layer was covered by pure polymer PDMS layers to provide the proposed antenna array with flexibility features. The simulation results of the proposed multilayered antenna array show an excellent enhancement in term of bandwidth (up to 2.416 GHz) and improvement in the efficiency of the antenna array compared to the conventional substrates FR-4 and Rogers.