Advanced RF/microwave filtering circuits for wireless communications and radar applications.

The recent rapid development in modern communication systems has presented some constraints caused by the introduced noises, as well as further requirements of low costs and miniature designs. Such noises are overcome using efficient designs of filtering devices which are essential components in many satellite, radar and mobile communication systems. As a result, balanced or differential filtering components have recently received increasing attention. A wideband microstrip balanced bandpass filter based on modified stub line approach is presented in here. The proposed idea of extended transmission lines (TLs) at the input and output (I/O) ports enables for very good stopband rejection and common-mode suppression. On the other hand, the recently introduced multilayer liquid crystal polymer (LCP) material and fabrication technique are exclusively applied in this work for adapting the potential solutions offered within. Therefore, a comprehensive in-house fabrication process has been developed and extensively illustrated in this thesis starting from mask preparation covering the entire procedure up to producing the final piece of output. As a demonstrator of the potential capability of multilayer LCP technology, a novel miniaturized ultra-wideband (UWB) balun with self-packaging is introduced in this study. The broadside coupled stripline structure is adopted in this work to realize UWB performance and TEM mode which results in excellent amplitude and phase balances. In turn, a novel compact UWB multilayer balanced bandpass filter using LCP technology is also presented in this thesis. The design utilizes the transversal signal-interference concept for realizing an outstanding common-mode suppression while constructed in a stripline configuration. All of the designs covered in this thesis are initially simulated using CAD tools to be then validated by measurements of fabricated prototypes

SARS-CoV-2 detecting rapid metasurface-based sensor

We have proposed a novel approach to detect COVID-19 by detecting the ethyl butanoate which high volume ratio is present in the exhaled breath of a COVID-19 infected person. We have employed a refractive index sensor (RIS) with the help of a metasurface-based slotted T-shape perfect absorber that can detect ethyl butanoate present in exhaled breath of COVID-19 infected person with high sensitivity and in-process SARS-CoV-2. The optimized structure of the sensor is obtained by varying several structure parameters including structure length and thickness, slotted T-shape resonator length, width, and thickness. Sensor’s performance is evaluated based on numerous factors comprising of sensitivity, Q factor, detection limit, a figure of merit (FOM), detection accuracy, and other performance defining parameters. The proposed slotted T-shape RIS achieved the largest sensitivity of 2500 nm/RIU, Q factor of 131.06, a FOM of 131.58 RIU-1 , detection limit of 0.0224 RIU

Design and Development of Ultrabroadband, High-Gain, and High-Isolation THz MIMO Antenna with a Complementary Split-Ring Resonator Metamaterial

The need for high-speed communication has created a way to design THz antennas that operate at high frequencies, speeds, and data rates. In this manuscript, a THz MIMO antenna is designed using a metamaterial. The two-port antenna design proposed uses a complementary splitring resonator patch. The design results are also compared with a simple patch antenna to show the improvement. The design shows a better isolation of 50 dB. A broadband width of 8.3 THz is achieved using this complementary split-ring resonator design. The percentage bandwidth is 90%, showing an ultrabroadband response. The highest gain of 10.34 dB is achieved with this design. Structural parametric optimization is applied to the complementary split-ring resonator MIMO antenna design. The designed antenna is also optimized by applying parametric optimization to different geometrical parameters. The optimized design has a 20 μm ground plane, 14 μm outer ring width, 6 μm inner ring width, and 1.6 μm substrate thickness. The proposed antenna with its broadband width, high gain, and high isolation could be applied in high-speed communication devices

6G Network Architecture Using FSO-PDM/PV-OCDMA System with Weather Performance Analysis

This paper presents a novel 160 Gbps free space optics (FSO) communication system for 6G applications. Polarization division multiplexing (PDM) is integrated with an optical code division multiple access (OCDMA) technique to form a PDM-OCDMA hybrid. There are two polarization states: one is X-polarization generated from adjusting the azimuthal angle of a light source at 0° while the other is Y-polarization which is generated by adjusting the azimuthal angle of a light source at 90°. Each polarization state is used for the transmission of four independent users. Each channel is assigned by permutation vector (PV) codes and carries 20 Gbps data. Four different weather conditions are considered for evaluating the performance of our proposed model. These weather conditions are clear air (CA), foggy conditions (low fog (LF), medium fog (MF), and heavy fog (HF)), dust storms (low dust storm (LD), moderate dust storm (MD), heavy dust storm (HD)), and snowfall (wet snow (WS) and dry snow (DS)). Bit error rate (BER), Q-factors, maximum propagation range, channel capacity, and eye diagrams are used for evaluating the performance of the proposed model. Simulation results assure successful transmission of 160 Gbps overall capacity for eight channels. The longest FSO range is 7 km which occurred under CA while the minimum is achieved under HD, which is 0.112 km due to large attenuation caused by HD. Within fog conditions, the maximum propagation distances are 1.525 km in LF, 1.05 km in MF, and 0.85 km in HF. Likewise, under WS and DS, the proposed system can support transmission distances of 1.15 km and 0.28 km, respectively. All these transmission distances are achieved at BER less than 10−5

Parametric Optimization and Numerical Analysis of GaAs Inspired Highly Efficient I-Shaped Metamaterial Solar Absorber Design for Visible and Infrared Regions

Renewable energy demand is increasing as fossil fuels are limited and pollute the environment. The solar absorber is an efficient renewable energy source that converts solar radiation into heat energy. We have proposed a gallium arsenide-backed solar absorber design made with a metamaterial resonator and SiO2 substrate. The metamaterial resonator is investigated with thin wire metamaterial and I-shaped metamaterial designs. The I-shape metamaterial design outperforms the thin wire metamaterial design and gives 96% average absorption with a peak absorption of 99.95%. Structure optimization is applied in this research paper using parametric optimization. Nonlinear parametric optimization is used because of the nonlinear system results. The optimization method is used to optimize the design and improve the efficiency of the solar absorber. The gallium arsenide and silicon dioxide thicknesses are modified to see how they affect the absorption response of the solar absorber design. The optimized parameter values for SiO2 and GaAs thicknesses are 2500 nm and 1000 nm, respectively. The effect of the change in angles is also investigated in this research. The absorption is high for such a wide angle of incidence. The angle of 30° only shows a lower absorption of about 30–50%. The effect of the change in angles is also investigated in this research. The design results are verified by presenting the E-field results for different wavelengths. The optimized solar absorber design applies to renewable energy applications