This letter presents SiC/Si diodes fabricated by the selective growth of SiC on Si substrate under ambient (atmospheric) conditions. The selective growth of β-SiC was obtained by irradiating a high-power KrF excimer laser beam on a polymethyl methacrylate (PMMA)-coated Si wafer. The laser decomposed carbon atoms from the PMMA, which dissolve into molten Si to form SiC. The Raman spectrum of the grown samples shows a dominant band in the range of 930-990 cm ^-1 , i.e., the spectral region characteristic for β-SiC. The quality of SiC can be optimized by changing the induced power. The best performing SiC/Si diode shows a good rectification ratio of ~3×10 ⁴ (±1 V), a low leakage current density of ~1 μA/cm ² (-1 V), and high breakdown (>200 V), which confirms the high quality of the SiC/Si interface. The doping of SiC was calculated from 1/C ² versus V plot and found to be ~5 × 10 ¹⁵ cm ^-3 . In addition, the measured photoelectric response shows a short circuit current density of 17 mA/cm ² , an open circuit voltage of 0.33 V, and a fill factor of 62%.

This paper presents the fabrication and characterization of radio frequency (RF) and microwave passive structures on an air substrate using additive manufacturing (3-D printing). The air substrate is realized by 3-D printing RF structures in two separate pieces and snapped together face to face using a LEGO-like process. Spacers printed on the periphery provide the desired air substrate thickness. Metal patterning on nonplanar printed plastic structures is carried out using a damascene-like process. Various RF structures such as low dispersion transmission line, T-line resonator, high-gain patch antenna, slot antenna, and cavity resonator are demonstrated using this process. Good performance is achieved; for example, measured 50-Ω transmission line shows low loss of 0.17 dB/cm at 4 GHz, and a patch antenna (center frequency of 4.5 GHz) shows gain and bandwidth of 7.6 dB and 0.2 GHz, respectively. Details of both measured and simulation results are presented.

In this paper, a variety of 3D printed microwave antennas are presented including wide band, narrow band, multiband and reconfigurable designs. In particular, single layer patch, folded E-patch, a bilateral Vivaldi, Spartan logo and Lego-like assembled antennas are demonstrated. 3D printing provides significant flexibility in the design of antennas that combine the assembly of both dielectric and metal layers to achieve desired performance characteristics such as resonant frequency and radiation pattern. Also, small Lego-like blocks can be printed that allows in the design and assembly of novel antennas structures using a combination of dielectric and metal coated blocks.

The advent of electric and flying vehicles (EnFVs) has brought significant advancements to the transportation industry, offering improved sustainability, reduced congestion, and enhanced mobility. However, the efficient routing of messages in EnFVs presents unique challenges that demand specialized algorithms to address their specific constraints and objectives. This study analyzes several case studies that investigate the effectiveness of genetic algorithms (GAs) in optimizing routing for EnFVs. The major contributions of this research lie in demonstrating the capability of GAs to handle complex optimization problems with multiple objectives, enabling the simultaneous consideration of factors like energy efficiency, travel time, and vehicle utilization. Moreover, GAs offer a flexible and adaptive approach to finding near-optimal solutions in dynamic transportation systems, making them suitable for real-world EnFV networks. While GAs show promise, there are also limitations, such as computational complexity, difficulty in capturing real-world constraints, and potential sub-optimal solutions. Addressing these challenges, the study highlights several future research directions, including the integration of real-time data and dynamic routing updates, hybrid approaches with other optimization techniques, consideration of uncertainty and risk management, scalability for large-scale routing problems, and enhancing energy efficiency and sustainability in routing. By exploring these avenues, researchers can further improve the efficiency and effectiveness of routing algorithms for EnFVs, paving the way for their seamless integration into modern transportation systems.

This paper investigates a step by step design procedure of a hybrid passive wireless sensor. The hybrid sensor measures both the electrical (dielectric constant) and the mechanical (viscosity) properties of liquid, providing a two-factor quality control. The hybrid sensor is based on an inductor-capacitor resonant tank coupled with a magnetoelastic strip. The mechanical and the electrical resonances change as a function of viscosity and dielectric constant, respectively. Two different hybrid sensor designs are investigated: 1) a parallel plate capacitor coupled with a separate amorphous ferromagnetic magnetoelastic strip (Metglas) and 2) a capacitor made using two parallel mounted magnetoelastic strips. The sensors are integrated as part of the “smart vial” making it field operable for food quality monitoring and control. Here, detection of adulteration in extra virgin olive oil is achieved by measuring the change in viscosity and dielectric constant for different adulteration levels. The real part of the dielectric constant for different liquid samples is measured in the frequency range of 3-24 MHz. The hybrid sensor is able to detect adulteration levels below 10% in volume. These sensors can be integrated with passive RFIDs for simultaneous measurement of multiple samples in an array format.

This paper presents the design and characterization of 3D printed photonic crystal filter (quasi optic component) and dielectric ridge waveguide (integrated component). Commercially available 3D printer was used to print polymer based components. Design and characterization of these devices is carried out over a frequency range of 0.15 - 0.5 THz. The photonic crystal filter shows a stop band from 0.25 - 0.35 THz. Also a very narrow defect mode (notch filter) was introduced by altering the structure of photonic crystal. The dielectric ridge waveguide shows broadband THz propagation characteristics. The transmission loss was determined to be largely dominated by the loss characteristics of the polymer material used.