This paper presents a trust-region parallel Bayesian optimization (TRPBO) method for simulation-driven antenna design problems. In this method, a multi-points acquisition function and trust region-based design space were developed to accelerate the solution efficiency of antenna design optimizations. For each optimization cycle in TRPBO, the acquisition function is applied to choose multiple updating points in a dynamic sampling space managed by a gradient-free trust region, and then the responses at the updating points are calculated using parallel electromagnetic simulations. The proposed TRPBO was illustrated and tested on several benchmark problems, and then the TRPBO was applied to perform the design optimizations of a circularly polarized antenna, two wideband antennas and an array antenna. Compared with the state-of-the-art methods, the proposed TRPBO achieves better optimization results with significantly less calculation time. The measured results of three fabricated antenna prototypes further show great potential of the TRPBO for solving simulation-driven antenna design problems.

A two-dimensional (azimuth and elevation) beam steering partially reflective surface (PRS) antenna is proposed in this paper. It consists of a probe-fed square patch antenna acting as the radiator and a reconfigurable PRS structure serving as the beam steering superstrate. The reconfigurable superstrate employs 6×6 reconfigurable unit cells and is equally divided into four sections. By controlling the states of the PIN diodes inserted in each unit cell, four sections have diverse biasing combinations, which can generate 10 different radiation models. As a result, the proposed antenna can radiate a boresight beam or a ±22° tilted beam in the plane of phi=0°, 45°, 90°, 135°. To verify the design feasibility, an antenna prototype operating at 5.5 GHz is fabricated and measured. The simulated and measured results for the input reflection coefficients and radiation patterns are in good agreement. The measured realized gains are around 10 dBi for all states. Moreover, the gain variation from the broadside direction to the tilted direction (22°) is less than 0.8 dBi. Compared with some reported two-dimensional beam steering PRS antennas, the proposed design can achieve a much wider beam tilting range with a more stable radiation performance and fewer tunable diodes.

A novel study on monitoring and analysis of debilitating condition of patients suffering from neurological disorder is presented. Parkinson’s disease is characterized by limited motor-ability of a patient. Freezing-of-gait is a major non-motor condition among ageing patients and its evaluation can reduce the chances of any secondary disorders. In this work, amplitude and phase information of the radio signals observed for a fixed period of time are used to differentiate the motor and non-motor symptoms. The amplitude information is classified using Support Vector Machine while linear transformation is applied to obtain sanitized phase information for detection. The proposed method is very handy with minimum deployment overhead. The analysis shows that this method also offers a high accuracy level of around 99% based on the observation of a number of patients. These features make it an attractive solution for real-time patient monitoring systems.

A non-intrusive sleep apnea detection system using a C-Band channel sensing technique is proposed to monitor sleep apnea syndrome in real time. The system utilizes perturbations of RF signals to differentiate between patient's breathing under normal and sleep apnea conditions. The peak distance calculation is used to obtain the respiratory rates. A comparison of the datasets generated by the proposed method and a wearable sensor is made using a concordance correlation coefficient to establish its accuracy. The results show that the proposed sensing technique exhibits high accuracy and robustness, with more than 80% concordance with the wearable breathing sensor. This method is, therefore, a good candidate for the real-time wireless detection of sleep apnea.

A novel design concept to reduce the frequency- ratio of a dual-band dual-circularly polarized (CP) microstrip patch antenna (MPA) is presented by using its reshaped TM10, TM01, and TM20 modes. Firstly, the far-zone radiated fields of the traditional MPA are theoretically investigated. It demonstrates that the broadside |E| and |E| fields of xoz-plane radiation patterns are orthogonally generated under TM10 and TM01 modes, respectively. Unfortunately, the antenna working in TM20 mode radiates the non-broadside |E| component at xoz-plane. Then, an open-ended stub is loaded around the edge of the radiating patch, resulting in reshaping the TM20 mode as the broadside radiation. After that, the width of core radiator is decreased with the loaded of two shorting pins. The main target is to reallocate the TM01 mode resonating between TM10 and TM20 modes. In final, the proposed antenna is fabricated and tested. The results illustrate that its LHCP and RHCP radiation patterns are satisfactorily acquired at around 2.134 and 2.223 GHz, respectively, thus gaining a small frequency-ratio of around 1.04. Meanwhile, the antenna holds the low-profile (0.02 free-space wavelength), small backlobe, single-layer, single-fed, and single-radiator properties.

Medical healthcare is one of the fascinating applications using Internet of Things (IoTs). The pervasive smart environment in IoTs has the potential to monitor various human activities by deploying smart devices. In our pilot study, we look at narcolepsy, a disorder in which individuals lose the ability to regulate their sleep-wake cycle. An imbalance in the brain chemical called orexin makes the sleep pattern irregular. This sleep disorder in patients suffering from narcolepsy results in them experience irrepressible sleep episodes while performing daily routine activities. This study presents a novel method for detecting sleep attacks or sleepiness due to immune system attacks and affecting daily activities measured using the S-band sensing technique. The S-Band sensing technique is channel sensing based on frequency spectrum sensing using the orthogonal frequency division multiplexing transmission at a 2 to 4 GHz frequency range leveraging amplitude and calibrated phase information of different frequencies obtained using wireless devices such as card, and omni-directional antenna. Each human behavior induces a unique channel information (CI) signature contained in amplitude and phase information. By linearly transforming raw phase measurements into calibrated phase information, we ascertain phase coherence. Classification and validation of various human activities such as walking, sitting on a chair, push-ups, and narcolepsy sleep episodes are done using support vector machine, K-nearest neighbor, and random forest algorithms. The measurement and evaluation were carried out several times with classification values of accuracy, precision, recall, specificity, Kappa, and F-measure of more than 90% that were achieved when delineating sleep attacks.