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All Journal International Journal of Electrical and Computer Engineering TELKOMNIKA (Telecommunication Computing Electronics and Control) Bulletin of Electrical Engineering and Informatics Bulletin of Electrical Engineering and Informatics Bulletin of Electrical Engineering and Informatics Indonesian Journal of Electrical Engineering and Computer Science
Zahriladha Zakaria
Universiti Teknikal Malaysia Melaka (UTeM)
Computer Science & IT Electrical & Electronics Engineering Engineering

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Wideband power amplifier based on Wilkinson power divider for s-band satellite communications Mussa Mabrok; Zahriladha Zakaria; Tole Sutikno; Ammar Alhegazi
Bulletin of Electrical Engineering and Informatics Vol 8, No 4: December 2019
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (631.684 KB) | DOI: 10.11591/eei.v8i4.1552

Abstract

This paper presents design and simulation of wideband power amplifier based on multi-section Wilkinson power divider. Class-A topology and ATF-511P8 transistor have been used. Advanced Design System (ADS) software used to simulate the designed power amplifier. The simulation results show an input return loss (S11)<-10dB, gain (S21)>10 dB over the entire bandwidth, and an output power around 28dBm at the Centre frequency of 3GHz. The designed amplifier is stable over the entire bandwidth (K>1). Inter-modulation distortion is -65.187dBc which is less than -50dBc. The designed amplifier can be used for the microwave applications which include weather radar, satellite communication, wireless networking, mobile, and TV.
Design of Quasi-Elliptic Bandpass Filter for Substrate Integrated Waveguide (SIW) Using Cross Coupling Technique Muhajir Mustapa; ZahrilAdha Zakaria; Noor Azwan Shairi
Indonesian Journal of Electrical Engineering and Computer Science Vol 12, No 3: December 2018
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v12.i3.pp1366-1372

Abstract

This paper proposes a quasi-elliptic band pass filter in substrate integrated waveguide (SIW) by using cross coupling technique to produce transmission zeros (TZs) at both side. Finally, a fourth pole SIW quasi-elliptic filter at 5.75 GHz is designed in single layer substrate. Simulation results show that the filter has a center frequency of 5.75 GHz with the bandwidth of 100 MHz. The minimum insertion loss in the passband is 0.3 dB, and the return loss is better than 20 dB. Due to the TZs, the SIW filter has rapid transition performance at both lower and upper sidebands, good selectivity is achieved, while the SIW filter presents a very compact implementation and goodspurious rejection.
High efficiency Doherty power amplifiers for modern wireless communication systems: A brief review Mussa Mabrok; Zahriladha Zakaria; Tole Sutikno
Indonesian Journal of Electrical Engineering and Computer Science Vol 23, No 3: September 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v23.i3.pp1855-1860

Abstract

Dueto the high peak to average power ratio (PAPR) of modern modulated signals, power amplifiers (PAs) have been forced to operate at the back-off (BO) region of their saturation power in order to avoid signal clipping and distortion. However, classical PAs suffer from low efficiency in the BO region operation. Therefore, efficiency has to be enhanced in that region. Many techniques have been proposed. Among them, the Doherty power amplifier (DPA) is considered as the most suitable technique due to its simple structure and high performance. However, its conventional design is limited to a 6 dB BO level, which does not satisfy the requirements of modern communication systems. In this paper, a brief review of the most significant techniques of high-efficiency DPA is presented. First, DPA topology and its operation principles are briefly discussed. Second, efficiency enhancement techniques such as an asymmetrical DPA, output combiner modification, gate bias adaption, offset line optimization, and multi-way DPA were discussed. The study shows that the most suitable, simple, and effective solution is an asymmetrical approach. However, it needs to be investigated in terms of bandwidth in order to meet the efficiency-bandwidth requirements of modern wireless communication systems such as 5G.
UWB Filtenna with Electronically Reconfigurable Band Notch using Defected Microstrip Structure Ammar Alhegazi; Zahriladha Zakaria; Noor Azwan Shairi; Tole Sutikno; Sharif Ahmed
Indonesian Journal of Electrical Engineering and Computer Science Vol 8, No 2: November 2017
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v8.i2.pp302-307

Abstract

A new design of filtenna with electronically reconfigurable band notch for ultra-wideband (UWB) applications is presented. The filtenna is designed based on modified monopole antenna integrated with resonant structure. To produce wider bandwidth with better return loss and higher frequency skirt selectivity, the monopole antenna is modified using microstrip transition in the feedline and block with a triangular-shape slot on each side of the circular patch. The resonant structure is about U-shaped slot defected on the feedline to achieve band notch characteristic. The position of the created band notch is controlled by optimizing the length of the U-shaped slot. By using a PIN diode switch inserted in the U-shaped slot to achieve reconfigurability feature. The experimental results show that the proposed design exhibits a wide bandwidth ranging from 3.0 to 14.0 GHz with reconfigurable band notch at 5.5 GHz (WLAN), and omnidirectional radiation pattern. Therefore, the proposed design is a good candidate for modern UWB applications.
Analysis and Investigation of a Novel Microwave Sensor with High Q-Factor for Oil Sensing Ammar Alhegazi; Zahriladha Zakaria; Noor Azwan Shairi; Tole Sutikno; Rammah A. Alahnomi; Ahmed Ismail Abu-Khadrah
Indonesian Journal of Electrical Engineering and Computer Science Vol 12, No 3: December 2018
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v12.i3.pp1407-1412

Abstract

In this paper, a novel microwave sensor with high Q-factor for oil sensing is analyzed and investigated. The new design is based on a gap waveguide cavity resonator (GWCR). To characterize and evaluate the sample, the oil under tested (OUT) is injected into a Teflon tube, which is passing through the microfluidic channel that is located in the middle of the cavity where the electric field concentrates. The results show that the proposed sensor has a high Q-factor of 4832. Moreover, the proposed design has the ability to sense and detect different types of oils with a small variation of permittivities such as Fish oil, Coconut oil, Olive oil, Linseed oil and Castor oil. The permittivity equation is extracted using the polynomial fitting method to define unknown dielectric properties of the OUT. The results show that the evaluated permittivity using the proposed sensor has a good agreement with the ideal permittivity. Therefore, the proposed sensor is a good candidate for oil processing in food industries.
SPDT discrete switch design using switchable SIW resonators for millimeter wave MIMO transceiver Amirul Aizat Zolkefli; Badrul Hisham Ahmad; Noor Azwan Shairi; Adib Othman; Zahriladha Zakaria; Imran Mohd Ibrahim; Huda A. Majid
Indonesian Journal of Electrical Engineering and Computer Science Vol 24, No 3: December 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v24.i3.pp1542-1549

Abstract

A single pole double throw (SPDT) discrete switch design using switchable substrate integrated waveguide (SIW) resonators is proposed in this paper. It was designed for the millimeter wave multiple input multiple output (MIMO) transceiver. An example application is for 5G communication in 26 GHz band. High isolation between transmitter and receiver (in the transceiver) is needed in SPDT switch design to minimize any high radio frequency (RF) power leakage in the receiver. Therefore, the use of switchable SIW resonators can achieve higher isolation if compared to the conventional series SPDT switch, where the isolation of the proposed SPDT is depend on the bandstop response of the SIW resonators. The switchable SIW resonators can be switched between allpass and bandstop responses to allow the operation between transmit and receive modes. As a result, the simulation and measurement showed that the proposed SPDT switch produced an isolation higher than 25 dB from 24.25 to 27.5 GHz compared to the conventional design.
Dual-band bandpass filter based on two U-shaped defected microstrip structure Mussa Mabrok; Zahriladha Zakaria; Yully Masrukin; Tole Sutikno
Indonesian Journal of Electrical Engineering and Computer Science Vol 22, No 2: May 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v22.i2.pp909-918

Abstract

This paper presents design of dual-band bandpass filter by integrating conventional quarter-wavelength short circuit stubs bandpass filter with U-shaped defected microstrip structure notch filter. Based on the parametric analysis, it is found that high attenuation level can be achieved by using two U-shaped defected microstrip structure separated by specific distance. The designed circuit simulated using advanced design system and fabricated based on Roger 4350B. The simulation results are in good agreement with measured results. The designed filter covered two pass bands centered at 2.51 GHz and 3.59 GHz with 3-dB fractional bandwidth of 15.94% and 15.86%, respectively, return losses better than 15 dB, and insertion losses better than 1 dB. The designed device can be used for wireless communication applications such as WLAN and WiMAX.
Design of compact ultra wideband antenna for microwave medical imaging application Adib Othman; Nur Ishmah Sabirah Shaari; Abdullah M. Zobilah; Noor Azwan Shairi; Zahriladha Zakaria
Indonesian Journal of Electrical Engineering and Computer Science Vol 15, No 3: September 2019
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v15.i3.pp1197-1202

Abstract

A compact ultra wideband (UWB) antenna for operation at 6 GHz intended for microwave medical imaging (MMI) application is proposed. The microstrip patch antenna (MPA) was design in hexagon shape which is contain H-slot at the centre top of the patch and a slot at the ground. Those slots method is utilised to enhance the operating bandwidth as well as minimising the antenna’s impedance mismatch caused by its proximity to material. Results shows that, the implementation of slot on the patch has profoundly enhance the bandwidth (BW) of the antenna to 503.54 MHz. Measurement of fabricated antenna produce significant result in term of producing wide bandwidth of 520 MHz, with slightly shifting on operating frequency. Therefore, it has been proved that the required performance of UWB antenna has been achieved successfully. 
High efficiency Doherty power amplifier based on asymmetrical matching network Mussa Mabrok; Zahriladha Zakaria; Tole Sutikno
Indonesian Journal of Electrical Engineering and Computer Science Vol 23, No 2: August 2021
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v23.i2.pp910-917

Abstract

Doherty power amplifier (DPA) with high efficiency at the output power back off is highly demanded for modern wireless communication systems to achieve high data rates and reduce the power consumption and operation costs. This paper presents a new design strategy for enhancing DPA’s back-off efficiency. New design strategy called asymmetrical matching network is used to achieve asymmetric operation, which helps to compensate for the low power delivered by the peaking stage in the conventional DPA. The simulation results showed an enhancement in the back-off efficiency, where the proposed design is able toachieve 46-52% drain efficiency at 8 dB output power back-off while maintains high efficiency of 73-80 % at saturation over the designed bandwidth of 3.4-3.6 GHz. The proposed design is suitable for high efficiency sub-6 GHz fifth-generation wireless applications. 
Reconfigurable bandstop to allpass filter using defected ground structure in K-band for millimeter-wave communications Adib Othman; Noor Azwan Shairi; Huda A. Majid; Zahriladha Zakaria; Imran Mohd Ibrahim; Mohd Haizal Jamaluddin; Anwar Faizd Osman
Indonesian Journal of Electrical Engineering and Computer Science Vol 28, No 2: November 2022
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v28.i2.pp820-829

Abstract

In this paper, a reconfigurable bandstop to allpass filters using Defected Ground Structure (DGS) in K-Band for millimeter-wave communications is proposed. Mathematical analysis of the DGS is discussed in this paper for the bandstop and allpass responses. The reconfigurable filter is performed by using an ideal switch with open circuit and short circuit conditions on DGS at several locations. Hence, two filter designs with different DGS are investigated for their performance in both simulation and measurement. As a result, the ideal switch at location S3 gives the best performance for both DGSs with a narrowband bandstop response and a wideband allpass response with insertion loss of less than 1 dB and return loss of more than 10 dB at the 26 GHz band. Hence, the proposed reconfigurable filter is suitable for millimeter-wave front-end communications.
Co-Authors A. A. Md Isa A. Ahmad A. R. Othman Abdullah M. Zobilah Adib Othman Adib Othman Ahmed Ismail Abu-Khadrah Ahmed M. Dinar Amirul Aizat Zolkefli Ammar Alhegazi Anwar Faizd Osman Ariffuddin Joret Azahari Salleh Badrul Hisham Ahmad Faza Syahirah Mohd Noor Herwansyah Lago Herwansyah Lago Huda A. Majid Huda A. Majid Imran Mohd Ibrahim Ismail Bin Mohd M . K. Abdulhameed M. K. Abdulhameed Maizatul Alice Meor Said Mohamad Harris Misran Mohamad Zoinol Abidin Abd Aziz Mohd Fareq Abdul Malek Mohd Haizal Jamaluddin Mohd Khairy Ismail Mohd Mawardy Abdullah Mohd Nor Husain Mothana L. Attiah Mowafak K. Mohsen Muhajir Mustapa Muhammad Faiz Liew Abdullah Muhammad Suhaimi Sulong Mussa Mabrok Naim Che Pee Nasrullah Saifullah Noor Azwan Shairi Nornikman Hassan Norshidah Katiran Nur Ishmah Sabirah Shaari Nurhasniza Edward Nursyahirah Mohd Sanusi Rammah A. Alahnomi Rammah A. Alahnomi S. Alani Sajjad Ahmed Sam Weng Yik Sameer Alani Sharif Ahmed Siti Nadzirah Salleh Tole Sutikno Yosza Dasril Yully Erwanti Masrukin Yully Masrukin