Teguh Firmansyah

Bio: Teguh Firmansyah is an academic researcher from Sultan Ageng Tirtayasa University. The author has contributed to research in topics: Microstrip & Band-pass filter. The author has an hindex of 10, co-authored 55 publications receiving 220 citations. Previous affiliations of Teguh Firmansyah include Shizuoka University & University of Indonesia.

Dual‐wideband band pass filter using folded cross‐stub stepped impedance resonator

Abstract: In this letter, a dual-wideband band pass filter (DW-BPF) using cross-stub stepped impedance resonator (CS-SIR) was simulated, fabricated, and measured accordingly. The CS-SIR was used to replace the conventional half-wavelength open stub resonators. Compare to the conventional resonator, the CS-SIR resonator has a wider fractional bandwidth and ease of fabrication. Furthermore, the DB-BPF was fabricated on microstrip with ɛr = 4.4, h = 0.8 mm, and tan δ = 0.0265. The DW-BPF with CS-SIR achieves transmission-coefficients/fractional-bandwidth of 0.22 dB/94.19% and 1.87 dB/33.52% at 1.14 GHz and 2.31 GHz, respectively. In order to reduce the filter size, a folded CS-SIR (FCS-SIR) was also proposed. As a result, this BPF size was reduced to 53%, with the BPF size of 0.30 λG2 and 0.14 λG2 for DW-BPF with CS-SIR and DW-BPF with folded CS-SIR, respectively. The λG is the wavelength at the first frequency. Further, the DW-BPF with FCS-SIR achieves transmission coefficients/fractional bandwidth of 0.19 dB/89.08% and 1.29 dB/31.90% at 1.21 GHz and 2.41 GHz, respectively. Measured results are in a very good agreement with the simulated results.

Design of Triple-Band Bandpass Filter Using Cascade Tri-Section Stepped Impedance Resonators

Abstract: In this research, a triple-band bandpass filter (BPF) using a cascade tri section step impedance resonator (TSSIR), which can be operated at 900 MHz, 1,800 MHz, and 2,600 MHz simultaneously, was designed, fabricated and evaluated. Advanced Design System (ADS) was used to design and simulate the proposed BPF. The proposed BPF using cascade TSSIR was fabricated on an FR4 substrate with dielectric permittivity, substrate thickness and loss tangent at 4.3, 1.6 mm and 0.0017, respectively. The performance parameters of the proposed BPF were characterized by insertion loss, return loss, voltage standing wave ratio (VSWR) and group delay. The performance results from the simulation were compared to those of the fabricated BPF. The results showed that the performances from both the simulated and the fabricated BPF satisfied the design specifications and were in close agreement with each other. Furthermore, the results indicated that the proposed BPF using cascade TSSIR performed better than a hairpin BPF with TSSIR.

A highly independent multiband bandpass filter using a multi-coupled line stub-sir with folding structure

Abstract: The main problem in designing a multiband bandpass filter (BPF) is making each passband response highly independent, where each bandwidth of multiband BPF can be controlled and adjusted separately. To overcome this problem, this paper proposes a highly independent multiband BPF based on a multicoupled line stub-SIR with a folding structure. The proposed multiband BPF is constructed as a multicoupled line to generate a highly independent inter-passband. Moreover, the multiband performance is produced separately and independently by using three sets of resonators: resonator A1/A2 (R A1 and R A2 ), resonator B1/B2 (R B1 and R B2 ), and resonator C1/C2 (R C1 and R C2 ). The three passband frequencies can be independently arranged and designed. To miniaturize the multiband BPF, a folding structure is also proposed. As a result, the multiband BPF has a compact size that is reduced by over 61.29 % compared to previous structures. The even-odd excitation model and the equivalent circuit model are used to analyze the multiband BPF structure. This BPF is designed for GPS applications at 1.57 GHz, WCDMA (3G) at 1.8 GHz, WLAN (WiFi) at 2.4 GHz, LTE (4G) at 2.6 GHz, and 5G communication at 3.5 GHz. To evaluate and validate the proposed structure of the multiband BPF, the circuits are fabricated and tested. The simulated and measured results of the multiband BPF show good agreement. In conclusion, the proposed multiband BPF structure has a highly independent inter passband response and a compact size.

Bandwidth and Gain Enhancement of MIMO Antenna by Using Ring and Circular Parasitic with Air-Gap Microstrip Structure

Abstract: This research was proposed a circular patch MIMO antenna by using a ring and circular parasitic radiator structure. As a novelty, in order to enhance bandwidth and gain of circular patch MIMO antenna, a conventional circular patch MIMO antenna will be added a ring and a circular parasitic. Therefore, this research was investigated a conventional MIMO antenna (C-MA), ring parasitic MIMO antenna (RP-MA), and circular parasitic MIMO antenna (CP-MA) as Model 1, Model 2, and Model 3, respectively. This MIMO antenna was designed on FR4 microstrip substrate with r= 4.4, thickness h=1.6 mm, and tan = 0.0265. This MIMO antenna has center frequency 2.35 GHz which is a frequency band for LTE application in Indonesia. An Advance Design System (ADS) software was used to determine the antenna parameters. The MIMO antenna C-MA / RP-MA/ CP-MA achieves 2.36GHz/ 2.38GHz/ 2.38 GHz, 70 MHz/ 100 MHz/ 120 MHz, 1.625 dBi/ 4.066 dBi/ 4.117 dBi, 6.414 dBi/ 7.26 dBi/ 7.153 dBi, 33.9 %/ 47.8 %/ 49.70 %, -12.35 dB/ -22.21 dB/ -23.66 dB, and -30.924 dB/ -28.46 dB/ -27.59 dB for center frequency, bandwidth, gain, directivity, efficiency, reflection coefficient, and mutual coupling, respectively. Compared to C-MA (Model1) performances, The result showed that proposed antenna has wider-bandwidth/ higher-gain with 42.8%/ 150.2 %, and 71.4%/ 163.3% for RP-MA (Model 2) and CP-MA (Model 3), respectively. The proposed antenna has size of 50 mm x 130 mm x 23.2 mm. Measured results are in a good agreement with the simulated results.

A 3-10-Ghz low-noise amplifier with wideband LC-ladder matching network

Abstract: Reactive matching is extended to wide bandwidths using the impedance property of LC-ladder filters. In this paper, we present a systematic method to design wideband low-noise amplifiers. An SiGe amplifier with on-chip matching network spanning 3-10 GHz delivers 21-dB peak gain, 2.5-dB noise figure, and -1-dBm input IP3 at 5 GHz, with a 10-mA bias current.

Error-correction coding

Abstract: This report describes the progress made towards the completion of a specific task on error-correcting coding. The proposed research consisted of investigating the use of modulation block codes as the inner code of a concatenated coding system in order to improve the overall space link communications performance. The study proposed to identify and analyze candidate codes that will complement the performance of the overall coding system which uses the interleaved RS (255,223) code as the outer code.

Tantalum-Based Electrocatalyst for Polysulfide Catalysis and Retention for High-Performance Lithium-Sulfur Batteries

Abstract: Summary Polysulfide retention and catalysis are currently among the most important factors toward solving much of the technical challenges of lithium-sulfur (Li-S) batteries Taking advantage of the electronic structure specific to tantalum, we explore the application of amorphous tantalum oxide with oxygen vacancies embedded inside a microporous carbon matrix as an electrocatalyst for the Li-S system Through a pore-constriction mechanism, the dimensions of tantalum oxide are controlled to be nanosized with abundant polysulfide-retaining and catalytically active sites High cycle and rate performances were achieved at practically relevant sulfur loadings and electrolyte content We believe our identification of tantalum as a new catalyst material for Li-S batteries will incite more investigation into the specific selection of transition metals based on their electronic structures Meanwhile, the “ship in a bottle” strategy will enlighten the structure design for energy conversion and storage systems

Internet of Things Empowered Smart Greenhouse Farming

Abstract: The rapid change of climate, population explosion, and reduction of arable lands are calling for new approaches to ensure sustainable agriculture and food supply for the future. Greenhouse agriculture is considered to be a viable alternative and sustainable solution, which can combat the future food crisis by controlling the local environment and growing crops all year round, even in harsh outdoor conditions. However, greenhouse farms persist many challenges for efficient operation and management. The evolving Internet of Things (IoT) technologies, which encompass the smart sensors, devices, network topologies, big data analytics, and intelligent decision is believed to be the solution in addressing the key challenges facing the greenhouse farming, such as greenhouse local climate control, crop growth monitoring, crop harvesting and etc. This paper reviews the current greenhouse cultivation technologies as well as the state-of-the-art of IoT technologies for smart greenhouse farms. The paper also highlights the major challenges that need to be addressed.

Highly Dispersed and Crystalline Ta2O5 Anchored Pt Electrocatalyst with Improved Activity and Durability Toward Oxygen Reduction: Promotion by Atomic-Scale Pt–Ta2O5 Interactions

Abstract: Developing highly active and durable Pt-based electrocatalysts for the oxygen reduction reaction (ORR) is a crucial target if actual commercial application of proton exchange membrane fuel cells (PEMFCs) is to be realized. Herein we show that utilizing highly dispersed and crystalline Ta2O5-modified carbon nanotubes (CNTs) as a support can stabilize Pt nanoparticles (NPs) by strengthening the metal–support interactions at the atomic scale, and furthermore, we show that this offers an efficient strategy to improve the ORR catalytic activity and durability of the Pt NPs. These were found to be selectively anchored on the interface of well-dispersed Ta2O5 NPs and CNTs, showing an atomic-coupled interfacial structure between Pt and Ta2O5 with lattice overlap of Pt (200) and Ta2O5 (001). X-ray absorption near edge structure (XANES) analysis shows that the electronic structure of Pt is perturbed by Ta2O5 by virtue of the formation of strong Pt–O–Ta bonds. The presence of highly crystalline Ta2O5 also induces th...