Norfatihah Bahari
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Preferred name
Norfatihah Bahari
Official Name
Norfatihah, Bahari
Alternative Name
Bahari, N.
Bahari, Norfatihah
Bahari, N. I.
Main Affiliation
Scopus Author ID
56610151300
Researcher ID
CCZ-6056-2022

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A triangular MIMO array antenna with a double negative metamaterial superstrate to enhance bandwidth and gain

2020-08-01 , Ojo R. , Jamlos M.F. , Soh Ping Jack , Mohd Aminudin Jamlos , Norfatihah Bahari , Lee Y.S. , Al-Bawri S.S. , Abdul Karim M.S. , Khairi K.A.

Multiple-input-multiple-output (MIMO) array antenna integrated with the double negative metamaterial superstrate is presented. The triangular metamaterial unit cell is designed by combining two triangular elements positioned in complementary on the same plane at different sizes. Such design with more gaps is used to excite rooms for more capacitance effects to shift the resonance frequency thus enlarging the bandwidth of the MIMO antenna. The unit cell is arranged in 7 × 7 periodic array created a superstrate metamaterial plane where the Cstray exists in parallel between the two consecutive cells. It is found that the existence of Cstray and gaps for each unit cells significantly influenced the bandwidth of the MIMO antenna. The higher value of the capacitance will lead to the negativity of permittivity. The superstrate plane is then located on top of the 4 × 2 MIMO with a gap of 5 mm. The integration resulted in improving the bandwidth to 12.45% (5.65-6.4GHz) compared to only 3.49% bandwidth (5.91-6.12GHz) of the MIMO antenna itself. Moreover, the negative permeability characteristic is created by a strong magnetic field between the complementary unit cells to have 14.05-dBi peak gain. Besides that, the proposed antenna managed to minimize the mutual coupling and improve the mean effective gain, envelope correlation coefficient, and multiplexing efficiency.

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An IoT-based automated gate system using camera for home security and parcel delivery

2024-02-08 , Mohd Wafi Nasrudin , Jamaluddin A.F. , Ismail I. , Norfatihah Bahari , Vijayasarveswari Veeraperumal , Wan Azani Wan Mustafa , Abdul Syafiq Abdull Sukor , Abdul Rahim A.N.

The Internet of Things (IoT) has made it possible to set up smart home security and parcel delivery. Therefore, this work proposed an automated gate system using camera for home security and parcel delivery with integrated Internet of Things (IoT). An automated gate system will capture and identify the image of face visitors and delivery riders for admin authentication to open the gate and parcel box. This proposed work is controlled and monitored through mobile apps. The primary purpose and inspiration of this work are to help the delivery rider put the parcel into the parcel box provided if there is no person in the house, and the owner can pick up the parcel without being broken or robbed when she/he comes back home. When the delivery rider presses the button near the gate, the admin will receive the notification "Someone coming,". The admin will click the "okay"button and the system will take a picture using the camera in Blynk App. After the admin verifies that is the delivery rider, the admin will open the box and the delivery rider can access the parcel door box and put the goods inside the box. Another advantage of this work, it also allows familiar people to access our home. The same process with the delivery rider where the visitor needs to press the bell and the admin needs to verify before the visitor can access the single gate. The result indicates that this work is able to monitor and control the gate and parcel door box using an IoT application.

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Antenna Performance Enhancement using AMC Structure for 5G Frequency Range

2023-02-01 , Norfatihah Bahari , Rokhizan M.Z.N. , Rashidah Che Yob , Mohd Wafi Nasrudin , Nur Hidayah Ramli , Mohd Aminudin Jamlos , Lago H.

This paper presents a microstrip patch antenna operated at the fifth generation (5G) frequency range, which is at 3.5 GHz. To enhance the performance of the proposed antenna, an Artificial Magnetic Conductor (AMC) structure is implemented into the design. The 1x3 AMC is sandwiched between two FR-4 substrates and the performance of the proposed antenna is compared with the antenna without AMC structure. The simulated results prove that the proposed antenna offers better reflection coefficient with-50.45 dB compared to only-15.55 dB for the conventional antenna. Wider bandwidth is also achieved with 427 MHz of frequency bandwidth as opposed to only 135 MHz for the antenna without AMC. Besides that, the integration of AMC enhances the gain of the antenna when 3.7 dBi is achieved in contrast to only 3.21 dBi for the conventional antenna. Moreover, the efficiency of the antenna with AMC is also improved up to 68.54%. Furthermore, the ability to shrink 52.23% of the size of the antenna without AMC making it very favorable to be applied in 5G bands.

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Compact Parallel Coupled Line Microstrip BPF Design for 5G Applications

2023-01-01 , Anak Temuli H.U. , Khairul Najmy Abdul Rani , Fairul Afzal Ahmad Fuad , Khairil Syahmi Musa , Norfatihah Bahari , Faizah Abu Bakar , Mohd Aminudin Jamlos , Rahayu Y.

A compact parallel coupled line microstrip bandpass filter (BPF) for sub-6 GHz fifth generation (5G) applications is designed operating between edge frequencies of 3.40 and 3.80 GHz. The design is designed and simulated by means of the Advanced Design System (ADS) software using the flame retardant-4 (FR-4) board as the substrate. The BPF design applies the insertion loss method (ILM) to generate a parallel coupled line filter structure that performs passband permission and unwanted noise attenuation below 3.40 GHz and above 3.80 GHz, respectively. Consistent and relevant performances in terms of matching impedance, return loss (S11), insertion loss (S21), voltage standing wave ratio (VSWR), far field radiation pattern, gain, directivity, and radiated efficiency promise the microstrip BPF design has a potential for sub-6 GHz 5G applications.

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Compact bidirectional circularly polarized dedicated short range communication antenna for on-board unit vehicle-to-everything applications

2020-05-01 , Rahman N.A.A. , Mohd Aminudin Jamlos , Jamlos M.F. , Soh Ping Jack , Norfatihah Bahari , Hossain T.M.

This article presents a newly circularly polarized (CP) antenna for V2X's dedicated short range communications applications. Its CP characteristic is enabled by a 70 Ω sequential phase feeding network and sequential rotation technique designed on top of the substrate. It has features of ≈90° phase difference in sequence between ports of S21 = 2.4°, S31 = −87°, S41 = −180°, and S51 = −276°, resulting in a 2.19 dB axial ratio centered at 5.9 GHz. The length of the SP feeding network to each ports designed in the different form of meander lines are the key to control the generated phase at the center frequency It also contributes to the smaller final size of 0.59λ × 0.59λ. The proposed antenna operated from 5.850 to 5.925 GHz with a gain between 4 and 6 dBi. The gains are radiated in bidirectional mode due to the presence of the complimentary dipoles located on the opposite side of the substrate. These features indicate the suitability of the proposed antenna in compliance to the ITS-G5 OBU V2X standard.

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Cylindrical Dielectric Resonator as Dielectric Matching on Microwave Amplifier for the Unconditionally Stable and Conditionally Stable Transistor at 5 GHz Frequency

2022-12-01 , Rashidah Che Yob , Mahyuddin N.M. , Ain M.F. , Mohd Aminudin Jamlos , Nur Hidayah Ramli , Norfatihah Bahari , Mohd Wafi Nasrudin , Liyana Zahid

Stability and matching techniques on microwave amplifier have been an important consideration to maintain their required performances, but typically its frequency dependent. Thus, a frequency variable mechanism is required. The dielectric matching employing the stability and matching techniques on microwave amplifier with cylindrical dielectric resonator has been investigated and realized. The cylindrical dielectric resonator (CDR) with parallel microstrip lines is proposed at 5 GHz frequency for unconditionally stable and conditionally stable transistor as dielectric matching. Hence, the proposed dielectric resonator with +2 mm spacing and 155Ëš of curved configuration indicated the best performances for preliminary study. The result improves the performance of the parallel inhomogeneous CDR by 9.77%. Subsequently, the homogeneous CDR is also successfully working as the variable frequency mechanism for unconditionally stable and conditionally stable transistor at 5 GHz frequency in maintaining their stability performances.

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An Impedance Matching Network towards Amplifier Design from Conceptual to Practical: Simulation Study

2021-07-26 , Yob R.C. , Ramli N.H. , Norfatihah Bahari , Zahid L. , Nasrudin M.W.

In many systems, the impedance matching networks are vital to ensure their having good performances, especially in such systems performances that related to the gain, linearity, and quality factors. This article mainly focuses on the simulation study of the impedance matching network from conceptual to practical on amplifier design. This simulation study from the conceptual of the ideal transmission-line based design to the practical of the microstrip-line based circuit implemented by using LineCalc of the ADS tool. The gallium nitride high electron mobility (GaN-HEMT) transistor by Cree is being one of the key components in understanding the importance of the impedance matching networks on the amplifier design a t the operating frequency of 5 GHz. The Agilent's Advance Design Systems (ADS) is used to perform this research. The obtained voltage standing wave ratio (VSWR) are approximately to 1 for both conceptual and practical of the impedance matching towards the amplifier design a t5 GHz. Thus, it is showing the maximum power transfer was occurring from the power stages to the load.

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Artificial Magnetic Conductor to Enhance Microstrip Patch Textile Antenna Performance for WiMAX Application

2020-12-18 , Zahid L. , Abu Bakar H. , Abdul Rani K.N. , Thennarasan Sabapathy , Mohd Aminudin Jamlos , Mohamad Rizal Abdul Rejab , Musa K.S. , Hamzah D. , Norfatihah Bahari , Rashidah Che Yob

A rectangular microstrip patch textile antenna with Artificial Magnetic Conductor (AMC) operated at the center frequency of 5.80 gigahertz (GHz) for Worldwide Interoperability for Microwave Access (WiMAX) application was designed and simulated using the CST Microwave Studio 2016 and fabricated in this study. The use of AMC could solve the inflexibility of FR4 substrate that limits human body movement and reduce the radiation scattered on the human body whilst increasing the antenna gain and directivity. The antenna consists of 5 5 square shape gap of AMC unit cells ground layer using ShieldIt Super, five substrate layers using cotton (viscose) fabric as well as patch layer and another ground layer using the same ShieldIt Super. AMC is a metamaterial that imitates the conduct of zero reflection phase of Perfect Magnetic Conductor (PMC) on the resonant frequency not evidently existed in nature. Overall, the antenna with AMC has the significant return loss, S11 below than -30 decibel (dB), gain improved to more than 8 dB, and directivity elevated to more than 9 dBi at resonant frequency near to 5.80 GHz, respectively.

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Gain enhancement of microstrip patch antenna using artificial magnetic conductor

2019-03-01 , Norfatihah Bahari , Jamlos M.F. , Muammar Mohamad Isa

The paper presents an artificial magnetic conductor (AMC) structure to enhance the gain of the double microstrip patch antenna. By placing this kind of metamaterial in between the two Rogers RT5880 substrates, the antenna achieved lots of improvement especially in terms of size miniaturization, bandwidth, return loss, gain and efficiency. The antenna is intended to operate at 16 GHz where the prospect fifth generation (5G) spectrum might be located. Integration of AMC structure into the proposed antenna helps to improve nearly 16.3% of gain and almost 23.6% of size reduction.

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Left-Handed Metamaterial Wearable Antenna at 5G Frequency Range for Wireless Body Area Network

2023-01-01 , Ramli N.H. , Lokman M.A.F. , Norfatihah Bahari , Liyana Zahid , Rashidah Che Yob , Mohd Hafizuddin Mat , Mohd Aminudin Jamlos , Alzubaidi L.H. , Hussein A.H.A.

Wearable antennas are typically required to be small in weight, provide high bandwidth, high gain and efficiency, low price, and be installation-free for many modern applications. Due to the non-static human movement, an antenna with wide-angle scanning is necessary. This project is carried out by designing a small metamaterials wearable antenna at a 5G frequency range. The combination of left-handed metamaterial (LHM) and the wearable antenna is designed to operate for such a system. Results prove that the small wearable metamaterial antenna offers good performances where the gain is 5.8 dBi with an efficiency of 91.86% and provides an omnidirectional radiation pattern compared to the wearable antenna without LHM structure. The communication links of the antenna between the base station and the human body are investigated. The antenna can receive the signals for long distances may be up to 2 meters with wide angles. All the results will be a guideline while designing the systems in the future.

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