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All Journal Bulletin of Electrical Engineering and Informatics ELKOMIKA: Jurnal Teknik Energi Elektrik, Teknik Telekomunikasi, & Teknik Elektronika Jurnal Penelitian Pendidikan IPA (JPPIPA) Makara Journal of Technology International Journal of Electrical, Computer, and Biomedical Engineering (IJECBE) Journal of Robotics, Automation, and Electronics Engineering
Eko Tjipto Rahardjo
Universitas Indonesia
Agriculture, Biological Sciences & Forestry Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Education Electrical & Electronics Engineering Engineering Materials Science & Nanotechnology Mechanical Engineering Medicine & Pharmacology Physics

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Hybrid optical communications for supporting the Palapa Ring network Ucuk Darusalam; Fitri Yuli Zulkifli; Purnomo Sidi Priambodo; Eko Tjipto Rahardjo
Bulletin of Electrical Engineering and Informatics Vol 9, No 3: June 2020
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (973.832 KB) | DOI: 10.11591/eei.v9i3.2008

Abstract

In order to connecting villages in rural area with a city, a hybrid optical communication is proposed. The Optical fiber communications that are implemented as a backbone on the Palapa Ring network has an opportunity to be expanded to reach rural area through the implementation of free-space optical communications (FSO) as the optical relaying networks (ORN). The major problem of FSO as the ORN is turbulence effects induce an optical propagation. In this research, FSO as the ORN implements novel technique to improve the performance of hybrid FSO where the amplification of signal is produced through serial configuration of optical amplifiers in cascaded meanwhile to reduce the noise in the end of receiver, optical band pass filter is implemented. The simulation of hybrid FSO is performed in Optisystem 7.0 where ORN is implemented in two nodes. The length of optical fiber connection to FSO is set to be constant at 75 km. The range of optical propagation in FSO is set at 1–9.4 m. The results of simulation show that at the range of 1–8 Km of optical propagation under atmospheric turbulence, range values for SNR and BER are achieved at 46.23–26.61 dB and 6.7x10-17–1.5x10-6, respectively.
Design of Generating Dual Frequency Operation for Triangular Microstrip Antenna Using Electromagnetic Coupling Surjati, Indra; Rahardjo, Eko Tjipto; Hartanto, Djoko
Makara Journal of Technology Vol. 9, No. 2
Publisher : UI Scholars Hub

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Abstract

Design of Generating Dual Frequency Operation for Triangular Microstrip Antenna Using Electromagnetic Coupling. A new design is proposed in this paper by applying a pair of slits using a microstrip feed line. Therefore the microstrip line feeding system is electromagnetically coupled to the patch. The antenna works at two different frequencies in the range from 2 GHz to 4 GHz (S band frequency). The results of the simulation shows that the dual frequency operation can be created when the slit width is 1 mm and the height of the slits ranges from 10 mm to 14 mm with inter slit distance of 3 mm, 5 mm and 7 mm as well.
Two Element Microstrip Antenna Array with Defected Ground Structure Zulkifli, Fitri Yuli; Rahardjo, Eko Tjipto; Asvial, Muhamad; Hartanto, Djoko
Makara Journal of Technology Vol. 12, No. 2
Publisher : UI Scholars Hub

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Abstract

Two Element Microstrip Antenna Array with Defected Ground Structure. This paper presents a two element microstrip antenna array using trapezium shape defected ground structure (DGS). The DGS is inserted in the ground plane between two elements of antenna array. Insertion of the DGS is intended to suppress the mutual coupling effect produced by antenna array. Simulation and measurement results were taken and compared between antenna array with and without DGS. Measurement results show that the antenna with DGS compared to antenna without DGS can suppress mutual coupling effect to 7.9 dB, improve the return loss to 33.29% from -30.188 dB to -40.24 dB and axial ratio bandwidth enhancement to 10 MHz. This bandwidth enhancement is achieved from frequency 2.63 GHz – 2.67 GHz for antenna without DGS and from frequency 2.63 GHz – 2.68 GHz for antenna with DGS. In addition, the DGS antenna also improved the antenna gain to 0.6 dB. The results show that the implementation of the trapezium DGS can improve the radiation properties of the antenna without DGS.
Circularly Polarized Microstrip Array Antenna for Ground Segment in Quasi-Zenith Satellite System Zulkifli, Fitri Yuli; Rahardjo, Eko Tjipto
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

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Abstract

In satellite communication system, antenna plays an important role. Therefore, the antenna must meet some requirements, such as high gain, circular polarization, and good directivity. In this paper, a four element linear array triangular patch microstrip antenna with cross slot is designed to be used for Quasi-Zenith satellite system. A simulation study as well as experimental study was carried out. The simulation showed that the 3 dB axial ratio bandwidth of 87 MHz (2.569-2.656 GHz) is achieved while the measured results showed 96 MHz (2.556-2.652 GHz). The linear array of 4 element antenna has a gain of 13.73 dB and maximum radiation pattern at 40° and -40°. Simulation and experiment results show that this antenna has met the characteristic requirements of Quasi-Zenith satellite.
Radiation Characteristics of a Planar Strip Dipole Antenna and a Slot Dipole Antenna for THz Applications Apriono, Catur; Rahardjo, Eko Tjipto
Makara Journal of Technology Vol. 17, No. 3
Publisher : UI Scholars Hub

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Abstract

The development of a THz system often requires a device that is used to radiate or detect THz waves. One way to fulfill this requirement is to use an antenna. Therefore, we need to consider the radiation characteristics of an antenna working in the THz region. In this paper, we present simulation study of two dipole antennas, i.e. a planar strip dipole antenna and a slot dipole antenna. The simulation results show that a planar strip dipole antenna has a better radiation efficiency (more than 95%) compared to the slot dipole. It also shows that an efficiency of more than 98% can be achieved when using silicon dielectric substrate. Furthermore, a return loss characteristic of 38,752 dB can be achieved by using a silicon dielectric substrate and a metal layer of Au for the planar slot dipole antenna.
Performances of Free-Space Optical Communication System Over Strong Turbulence Darusalam, Ucuk; Priambodo, Purnomo Sidi; Sudibyo, Harry; Rahardjo, Eko Tjipto
Makara Journal of Technology Vol. 18, No. 1
Publisher : UI Scholars Hub

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Abstract

We report an experimental of free-space optical communication (FSOC) system that use tube propagation simulator (TPS) as the turbulence medium. The FSOC system use wavelength of 1550 nm at the rate transmission of 1000 Mbps and amplified with EDFA at the output of +23 dBm. Index structure of 10-15–10-13 as the representation of atmosphere index turbulences are used for simulation of intensity distribution model or scintillation. The simulation use gammagamma and K model as well. The beam wave propagation models used in simulation are plane wave, spherical wave and Gaussian wave. Spherical wave achieves highest performance via gamma-gamma in strong turbulence. While Gaussian wave achieves highest performance also via K model. We also found, characteristical FSOC system performance is calculated more accurately with gamma-gamma method for strong turbulence than K model. The performances from gamma-gamma for strong turbulence are at 22.55 dB, at 5.33´10-4, and at 9.41 ´10-6.
A New Method for Simulating Power Flow Density Focused by a Silicon Lens Antenna Irradiated with Linearly Polarized THz Wave Apriono, Catur; Rahardjo, Eko Tjipto; Hiromoto, Norihisa
Makara Journal of Technology Vol. 19, No. 2
Publisher : UI Scholars Hub

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Abstract

A terahertz system uses dielectric lens antennas for focusing and collimating beams of terahertz wave radiation. Linearly polarized terahertz wave radiation has been widely applied in the terahertz system. Therefore, an accurate method for analyzing the power flow density in the dielectric lens antenna irradiated with the linearly polarized terahertz wave radiation is important to design the terahertz systems. In optics, ray-tracing method has been used to calculate the power flow density by a number density of rays. In this study, we propose a method of ray-tracing combined with Fresnel’s transmission, including transmittance and polarization of the terahertz wave radiation to calculate power flow density in a Silicon lens antenna. We compare power flow density calculated by the proposed method with the regular ray-tracing method. When the Silicon lens antenna is irradiated with linearly polarized terahertz wave radiation, the proposed method calculates the power flow density more accurately than the regular ray-tracing.
Performance of Free-space Optical Communication Systems using Optical Amplifiers under Amplify-forward and Amplify-received Configurations Darusalam, Ucuk; Raj, Arockia Bazil; Zulkifli, Fitri Yuli; Priambodo, Purnomo Sidi; Rahardjo, Eko Tjipto
Makara Journal of Technology Vol. 24, No. 3
Publisher : UI Scholars Hub

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Abstract

With the growth of digital technology in the stage of industrial revolution 4.0, the demand for broadcasting large amounts of information to last mile users has increased. Free-space optical (FSO) communication is one of the telecommunication platforms that has shown immense potential in meeting the demand for information broadcasting. In this work, the performance of FSO communication based on wavelength division multiplexing with a data rate of 80 Gbps is investigated through simulations. The configuration of optical amplifiers in the FSO system is set up on the basis of the amplify-forward and amplify-received configurations to expand the network. The investigation is aimed at identifying the best optical signal amplification between an erbium-doped fiber amplifier (EDFA) and a semiconductor optical amplifier (SOA) under an atmospheric channel. Simulation results show that the EDFA performs better than the SOA in terms of the optical signal amplification for eight channels of the C band. The maximum optical propagation path length under the atmospheric channel for the amplify-forward and -received schemes using the EDFA is 1.7 km, with the bit error rate achieved at 10−6.
Reconfiguration of Polarized Antennas for WLAN Applications Filda Ayu Afrida; Fitri Yuli Zulkifli; Eko Tjipto Rahardjo
Jurnal Penelitian Pendidikan IPA Vol 9 No 7 (2023): July
Publisher : Postgraduate, University of Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jppipa.v9i7.4138

Abstract

Wireless technology based on the IEEE 802.11 standard and in accordance with the KEMINFO 2019 regulations requires antennas that can adapt to changing environments. Microstrip antennas are a good solution to meet the current technological advancements because they have several advantages, such as a simple design, lightweight, easy manufacturing, and low cost. When designing a microstrip antenna, bandwidth parameters must be observed. The bandwidth of a microstrip antenna is narrow. In order to work properly, some simple techniques can be used to increase antenna bandwidth. This research proposes a reconfigurable microstrip antenna polarization using a U-slot at a frequency of (2.4– 2.485) GHz for WLAN applications. The proposed antenna reconfiguration utilizes two (2) switching mechanisms that can be turned on and off individually or simultaneously. The results of the simulation showed that Ant. 1 and Ant. 2 have a linear polarization (LP), Ant. 1 has a bandwidth of 85 MHz (2.399 – 2.484) GHz, and Ant.2 has a bandwidth of 87 MHz (2.398– 2.485) GHz, both with S-parameter values ≤-9.54 dB. Then, Ant. 3 has a right circular polarization with a bandwidth value of 124 MHz (2.397 – 2.484) GHz, and Ant. 4 has a left circular polarization with a bandwidth value of 87 MHz (2.398 – 2.485) GHz at the Axial Ratio (AR) limit of ≤ 3 dB.
Design of a Dual-band Wearable Antenna Operating at 2.45 GHz and 5.8 GHz for Medical Communication Applications Rachman, Fajar Aulia; Rahardjo, Eko Tjipto
International Journal of Electrical, Computer, and Biomedical Engineering Vol. 2 No. 1 (2024)
Publisher : Universitas Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.62146/ijecbe.v2i1.31

Abstract

Indonesia's natural demographic which consists of 16,771 islands makes it has many challenges in infrastructure development, especially in the health sector. According to data, Indonesia currently has 10,203 Puskesmas and 2,449 hospitals. In terms of the number of medical personnel, currently in Indonesia there are 124,449 medical personnel. However, of the large number of medical personnel, 61.12% are concentrated in Java and Bali. This inequality causes the need for a technology that makes it easier for medical personnel to provide services to the community. Wireless Body Area Network (WBAN) is one of developed technology that supports telemedical services. In WBAN, wearable antenna is needed as a transmitter to transmit data. In this paper, a compact wearable dual band antenna was designed in ISM frequency band of 2.45 GHz and 5.8 GHz. A combination of rectangular shape radiating structure and cross slot is constructed to achieve dual band frequency. Jeans Textile material with permitivity of 1.7 and thickness of 1 mm is used for fabricating the proposed antenna. The size of antenna is 52.3mm x 58.69mm. The proposed antenna is simulated with and without human body panthom using cst software. The simulations result indicates that antenna resonates at frequency 2.45 GHz and 5.8 GHz with peak gains of 6.92 dBi and 6.5 dBi. SAR values when the proposed antenna simulated at wrist phantom ​​are 0.326W/kg and 1.024W/kg. When simulated at chest phantom, the SAR values ​​are 0.554W/kg and 0.394W/kg. Therefore, The proposed wearable antenna design is well suited for telemedical services.
Co-Authors Basari Basari Catur Apriono Djoko Hartanto Filda Ayu Afrida Fitri Yuli Zulkifli Harry Sudibyo Indra Surjati iqbal, muhamad wahyu Luh Putu Ratna Sundari Norihisa Hiromoto, Norihisa Nugroho Adi Saputro Purnomo Sidi Priambodo Rachman, Fajar Aulia Raj, Arockia Bazil Rizky Hidayat Prasetyo Soares, Fidelio Ucuk Darusalam