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The far-ultraviolet C (UVC) light has been used recently as an alternative disinfection system to deactivate the novel coronaviruses that cause coronavirus disease (COVID-19) without introducing any health damage to humans. We investigate that the far-UVC light from far-UVC excimer lamps (BEST 20 Watt) is a promising candidate for a far-UVC disinfection system to prevent human-to-human transmission of COVID-19. The optical characterization of far-UVC excimer lamps was examined. The maximum irradiance of the far-UVC excimer lamps is 219 nm, which is known to have antimicrobial capabilities on microorganisms, including coronaviruses. We propose a design of a disinfection chamber system based on eight 219 nm far-UVC excimer lamps which are attached vertically about 35 cm to each other, and the irradiation angle was installed at the angle of approximately 120° in order to optimize the irradiation of far-UVC light to a human body. For microorganism inactivation at a distance of around 10 cm from the human body, 219 nm far-UVC excimer lamps requires less than 5 s of irradiation time and the required intensity of 840 mW/cm2 at a low dose of 3000 mJ/cm2. We recommend that our proposed disinfection chamber can be used for humans and applied in public areas to decrease the spread of COVID-19 without any adverse health effect.

Collision is the main issue in safe transportation, including in the railway system. Sensor systems have been developed to detect obstacles to prevent a collision, such as using cameras. One disadvantage of the camera systems is that performance detection decreases in a not clean environment, like the target position behind the fogs. This paper discusses the development of frequency modulated continuous wave (FMCW) radar signal processing for high-speed railway collision avoidance. The development of radar signal processing combines a two-dimensional constant false alarm rate (2D-CFAR) and robust principal component analysis (RPCA) to detect moving targets under clutter. Cell average (CA) and Greatest of CA (GOCA) CFAR are evaluated under a cluttered wall environment along the railway track. From the experiment, the development of FMCW radar can detect stationary or moving obstacles around 675 meters in front of the locomotive. Combining 2D-CFAR and RPCA algorithm outperforms average background subtraction in extracting moving targets from strong clutter signals along the railway track.

This paper presents a study of a narrow bandwidth of the bandpass filter with a cross-coupled line structure. This structure was designed to have a good filter selectivity with the transmission zeros and a simple design. Since the structure has a cross shape, cross-coupling between the resonators consequently occurs. This interferes with the passband of the filter. Optimization in the size of the coupled lines and transmission lines was done to minimize the interference. Rogers RT/duroid 5880 was used as a substrate to fabricate the bandpass filter to verify the proposed design. As a result, the fabricated cross-coupled line bandpass filter has an 80 MHz of 3 dB bandwidth with operating frequency ranges from 2.97 GHz to 3.05 GHz. The bandwidth is reduced by 20 % from the specification.It shows that the cross-coupled line structure can yield a narrow bandwidth. Based on the 3 dB bandwidth, the center frequency is shifted 0.33 % above the specification. Meanwhile, the return loss and insertion loss of the proposed bandpass filter successfully comply with the required specifications. In conclusion, the proposed bandpass filter can be applied to S-Band applications that require narrow bandwidth.

Microwave imaging, such as images for radiological inspection in the medical profession, is one of the applications utilized in ultra-wideband (UWB) frequency ranges. The Vivaldi antenna is one of the most popular antennas for this purpose. The antenna is utilized because of its simple, lightweight, and compact design, as well as its excellent efficiency and gain capabilities. In this work, we present a high-gain Vivaldi antenna for microwave imaging applications. The proposed Vivaldi antenna is designed using a double-slot structure method with the addition of corrugated edges and a semicircle director aimed at improving the gain. The antenna is designed to operate at frequencies ranging from 3.1 to 10.6 GHz. Based on the modeling findings, the suggested antenna attain a bandwidth of 7.5 GHz with operating frequencies from 3.1 GHz to 10.6 GHz for a VSWR of less than two. In comparison to a typical single slot antenna, the suggested antenna provides a substantial boost in gain performance. The increase in gain is proportional to the frequency of operation. The constructed antenna has a lower bandwidth than the simulated one, with operating frequencies of 3.5 GHz – 3.75 GHz and 4.25 – 10.89 GHz, respectively, and useable bandwidths of 250 MHz and 6.64 GHz. All these results suggest that the antenna is suitable for microwave imaging applications.

Optical waveguides are important for guiding lightwave from a place to other places. Propagation and insertion losses of the optical waveguides should be considered to be in low values. Recently, optical waveguides with circular structures, which are optical fibers, are used widely for guiding lightwave in long-distance optical communication with very low propagation and insertion losses. Simultaneously, optical waveguides with planar structure are also developed for short distance communication in optical devices. We have reported design and analysis of the planar optical waveguides. In this paper, fabrication of planar optical waveguides using a polyimide material on thin silicon dioxide combined with the silicon substrate is reported. The polyimide material is used for the core of the optical waveguides. The silicon dioxide located on the silicon substrate and the air is used for cladding of the optical waveguides. Fabrication of the optical waveguides such as oxidation, photoresist coating, masking, ultra-violet exposure, and etching was done. The fabricated optical waveguides were characterized physically using a standard microscope and scanning electron microscope (SEM). The fabrication processes and characterization results are reported and discussed in detail.

We analyze the interaction of microwave and optical electric field in a microwave polarization detector based on photonic technology for Electromagnetic Compatibility (EMC) measurement. The detector consists of two orthogonal optical waveguides and patch antennas embedded with two orthogonal gaps fabricated on an Electro-Optic (EO) crystal. Wireless microwave signals can be received, separated and converted directly to lightwave signals through optical modulation using the proposed detector. This detector operates with no external power supply and with low microwave distortion. Microwave polarization can be identified using the proposed interface. In addition, it enables us to measure the magnitude and phase of the wireless signal simultaneously. The analysis of the device was done and presented at the operation frequency of 26 GHz. The proposed interface can be applied for EMC measurement through the radio-over-fiber link.

Optical modulator using channel optical waveguides and planar patch-antennas with gaps on ferroelectric optical crystals were proposed. Basic operations for receiving a wireless microwave signal and directly converting it to a lightwave signal were demonstrated successfully using a prototype device with simple and compact structure. These devices operate with no external power supply and no additional modulation electrode. Therefore the microwave-lightwave conversion with low microwave distortion can be obtained. The advanced microwave-lightwave converters using patch-antennas with a pair of narrow gaps and their applications are also discussed

Cahaya dapat dirambatkan dengan efektif melalui pandu gelombang optik untuk aplikasi teknologi komunikasi. Pandu gelombang optik memiliki beberapa struktur seperti struktur melingkar (serat optik) dan struktur planar (pandu gelombang optik persegi).Serat optik pada umumnya digunakan untuk komunikasi jarak jauh dan pandu gelombang optik persegi digunakan untuk komunikasi jarak pendek. Dalam tulisan ini, dibahas pandu gelombang optik persegi dengan menggunakan bahan polimer pada substrat silikon dioksida untuk panjang gelombang optik 1,55 µm. Bahan polimer digunakan sebagai inti (core) dari pandu gelombang optik. Silikon dioksida dan udara digunakan sebagai selubung (cladding). Bahan polimer digunakan sebagai inti karena nilai indeks biasnya lebih besar dibanding material lain yang digunakan sebagai selubung. Analisis pandu gelombang optik dihitung dengan menggunakan software Wolfram Mathematica yang berdasarkan pada metode Marcatili dan persamaan Maxwell. Distribusi medan dan mode dispersi dari pemandu gelombang optik telah diperoleh untuk panjang gelombang optik 1,55 µm. Moda operasi dari pandu gelombang optik dapat dikontrol dengan mengatur ukuran panjang dan lebar dari inti. Analisis dan hasil pandu gelombang optik dibahas secara rinci.Pandu gelombang optik menggunakan bahan polimer pada substrat silikon dioksida dapat digunakan untuk rangkaian optik terpadu dan perangkat penginderaan optik.

Asymmetric parallel-cascaded micro-ring resonator (APCMR) is proposed. The proposed device is composed of two or more micro-ring-resonators with different diameter. The proposed device is designed using transfer matrix combined with signal flow graph methods. The designed device with crosstalk less than and equal -10 dB can be obtained by setting coupling coefficient. The proposed device can be used for optical filters and sensors.

Optical waveguides are the key component for distributing optical signals with very low propagation loss in optical communication. Several type optical waveguides are established currently such as silica optical fiber. In the planar structure, planar optical waveguides are suitable for implementing to integrated optic applications. In here, rectangular optical waveguides on a planar structure with a LiTaO3 crystal as the substrate are described. The optical waveguides were designed for single mode operation at infrared optical wavelength. The Marcatili method is used for designing by separated the rectangular optical waveguides into two slab optical waveguides. Design rules for the rectangular optical waveguides are discussed in this paper