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This paper presents a performance comparison of the circular patch unit cell as a unit cell for reflector application at 3.5 GHz frequency using a dielectric substrate between FR4 and F4BMX220 substrates. A circular patch is chosen as the unit cell of a reflector because it is commonly used, fabricated, and has a wider bandwidth compared to other structures. A performance comparison of the circular patch on both dielectric substrates is presented in a graph of S-parameters, reflection phase, and operating bandwidth, as well as in the table of dimensions, where the result is performed by simulation using CST software. Based on the simulated results, the F4BMX220 has a better performance compared to the FR4 in terms of the reflection value, operating bandwidth, and dielectric substrate thickness. However, a circular patch diameter when using the F4BMX220 is bigger than when using the FR4 substrate because the FR4 substrate has a higher dielectric constant than the F4BMX220, which is twice the F4BMX220 dielectric constant. Also, the F4BMX220 substrate has a narrower bandwidth compared to the FR4 substrate, which is a difference of around 0.1 GHz. The circular patch when using the F4BMX220 substrate has 0.96 of a reflection value, 0.007 of an absorption value, -6.77° of the reflection phase, and 0.24 GHz of the operating bandwidth at the normal incident wave angle (0°). Also, it can be properly worked if the incident wave angle is moving until 60°. The F4BMX220 substrate has the best performance compared to the FR4 substrate because the reflection value is much better value, even at the incident wave angle of 60°.

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.

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.

Perkembangan budi daya ikan yang menggunakan keramba jaring apung (KJA), saat ini tersebar di berbagai waduk dan danau di seluruh Indonesia, saat ini tumbuh pesat dan menjadi andalan pendapatan daerah. Selama ini monitoring kualitas air dilakukan secara manual, yaitu melakukan pengukuran kualitas air di tempat budidaya ikan tersebut. Selain memerlukan waktu yang lama, biasanya budi daya ikan tersebut berada jauh dari pusat kota. Dalam makalah ini akan dijelaskan desain dan realisasi sistem monitoring kualitas air dan peringatan dini secara real-time yang terintegrasi. Sistem ini telah diterapkan secara khusus untuk memantau parameter suhu, DO (dissolved oxygen) dan pH di sentral budidaya ikan di Waduk Cirata. Tujuannya adalah memantau kualitas air secara real-time, bisa diakses di mana saja dan sekaligus mencegah kematian ikan secara massal yang disebabkan oleh terjadinya up-welling dengan menggunakan sistem peringatan dini. upwelling terjadi apabila nilai suhu menurun drastis mencapai 25 derajat celcius lalu nilai DO menurun sampai 2,38 mg/L. Di sisi lain, data dari stasiun pengukuran yang dikumpulkan di stasiun perantara dapat diakses atau dikirimkan ke stasiun pengendali dengan menggunakan sistem telemetri. Hasil dari penelitian ini memperlihatkan suatu sistem monitoring kualitas air untuk memantau parameter suhu, DO dan pH sekaligus peringatan dini terjadinya upwelling. Sistem ini untuk mendukung pembudidayaan ikan di danau-danau di Indonesia.

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.

Dewasa ini telah banyak dilakukan penelitian dan pengembangan radar . Salah satunya adalah radar yang ditempatkan di Kapal Laut. Penempatan radar di kapal laut mempunyai kendala pada tiang agung kapal. Tiang agung akan mengganggu fungsi radar karena adanya pantulan sinyal jarak dekat pada tiang agung. Hal ini dapat diantisipasi dengan mematikan pancaran radar saat arah pancaran radar menuju pada tiang agung kapal laut. Oleh sebab itu didalam penelitian ini dirancang prototype untuk mengatur otomatis aktif dan tidaknya pancaran radar berdasarkan arah pancaran radar. Kontrol aktif dan tidaknya pancaran radar ini dikontrol menggunakan perpaduan sensor ultrasonik dan sensor kompas dengan dilengkapi metode fuzzy sebagai logika jauh dekatnya tiang agung. Jika sensor ultrasonik membaca adanya halangan maka pancaran tidak aktif begitu sebaliknya. Penggabungan kedua sensor ini bertujuan jika sensor ultrasonik tidak dapat bekerja karena hujan maka kontrol sudut pada sensor kompas yang akan bekerja Setelah dilakukan perancangan dan pengujian pada alat ini maka diperoleh sudut deviasi dengan range 14,30 – 29,30 dengan eror ± 30. Dengan acuan jangkauan titik tiang agung 60-120cm dari poros radar dengan lebar tiang 30cm. Kecepatan yang diperoleh saat fuzzy berlangsung sebesar 20 kali rpm dari kecepatan normal saat prototype mengenai halangan. Serta adanya sensor hujan berperan sebagai switch sensor ultrasonik ke mode off dan mode on untuk sensor kompas dengan menggunakan inisialisasi awal. Dari data yang dihasilkan prototype ini maka diperoleh keberhasilan sebesar 85% dilihat dari pengujian beberapa sensor dan peggabungannya. Oleh sebab itu apabila prototype ini direalisasikan akan membantu penelitian industri perkapalan dalam pembuatan radar sesungguhnya.

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

Filter will be one of the most important components of the next generation of optical communications. Micro-ring resonators have been widely studied as a potential device for dense wavelength filter due to its advantages. In this paper, a waveguide-based microring-resonator type of interleave filter is investigated. The cascade structure is applied to obtain better characteristics of filter spectra. Our calculation shows that, compared with 2-stage or 4-stage cascade, 3-stage cascaded microring resonator has better performance with pass-band width of 22 GHz, ripple ratio < 1 dB, crosstalk of -33 dB for 1×2 interleaver and -24 dB for 1×4 interleaver. Numerical calculation also clearly shows that general optical waveguide types is reasonable as microring resonator with insertion loss < 2 dB

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.