Research Output
1 - 10 of 33
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PublicationDesign of a 1-Bit Programmable Coding Unit Cell Beamforming Metasurface( 2023-01-01)Traditional phased array antennas rely on costly phase shifters to steer beams by manipulating the phase of induced currents in each antenna element. In this study, we introduce a 1-bit coding metasurface as an alternative to traditional phased array antennas for beam control and modulation of electromagnetic waves. The metasurface operates at 5.8 GHz and consists of digitally controlled unit cells, each incorporating a pin diode. These diodes enable binary coding states of "1" and "0" with a significant 180-degree phase difference. The unit cell, with a dimension of 0.81λ x 0.81λ, comprises two metal patches separated by the pin diode on an FR-4 substrate. Simulation results demonstrate the distinct behavior of the metasurface, with the off-state exhibiting a reflection amplitude response of 1.8dB and the on-state showing a reduced amplitude due to on-resistance. The far-field patterns obtained from the simulations clearly indicate a 90-degree change in the radiation pattern between bit "0" and bit "1." This innovative design offers a cost-effective solution for beam control and versatile electromagnetic wave modulation, making it suitable for various applications, including beamforming in radar and communication systems.
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PublicationLow loss waveguide-based Butler matrix with iris coupling control method for millimeterwave applications( 2023-01-01)This paper proposes a low loss 4 × 4 Butler matrix based on rectangular waveguide cavity resonators technology for millimeterwave beamforming network using iris coupling method. This method has the advantage of controlling the electrical fields and the coupling factor inside a complex medium such as waveguide cavity resonators. The coupling factor of 6 dB for 4 × 4 Butler matrix is achieved by tuning the iris coupling k-value between the waveguide cavity resonators. Thus, avoiding a higher phase difference losses and component losses at upper millimeterwave bands. To validate the proposed method, CST software simulations are performed under several iris coupling k-values to achieve a 6 dB coupling factor. Then, the proposed 4 × 4 Butler matrix is 3D metal printed using selective laser melting (SLM) technique. The measured reflection and isolation coefficients are observed below −10 dB, with coupling coefficients ranging between −6 and −7 dB. The phase differences of −42.02°, 42.02°, −130.95°, and 133.3° are achieved at the outputs. It confirmed that using this proposed method has the superiority over the conventional microstrip and waveguide coupling methods by a 1 dB coupling factor loss and a 3° phase difference error.
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PublicationDesign of a Compact Reconfigurable Antenna with Hybrid Polarization and Frequency Control for Geofencing Application( 2023-01-01)A frequency reconfigurable antenna for location monitoring is proposed. The antenna developed can be reconfigured at two frequencies with suitable polarization and radiation pattern which designed for geofencing application, thus it either can operate at 1.575 GHz band or 2.45 GHz band. The expected outcome of this work is that when the user is within the geo-fence area it will use WIFI, while when the user exits the geo-fence area, GPS application will be selected. With the use of two switches, the antenna can operate either at band from 2.335 GHz to 2.593 GHz for S11< -10 dB and from 1.546 GHz to 1.588 GHz at S11 <-6 dB. The axial ratio results of less than 3 dB is achieved at 1.575 GHz with a bandwidth of 20 MHz.
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PublicationReconfigurable pattern patch antenna for mid-band 5G: A review( 2022-01-01)New requirements in communication technologies make it imperative to rehash conventional features such as reconfigurable antennas to adapt with the future adaptability advancements. This paper presents a comprehensive review of reconfigurable antennas, specifically in terms of radiation patterns for adaptation in the upcoming Fifth Generation (5G) New Radio frequency bands. They represent the key of antenna technology for materializing a high rate transmission, increased spectral and energy efficiency, reduced interference, and improved the beam steering and beam shaping, thereby land a great promise for planar antennas to boost the mid-band 5G. This review begins with an overview of the underlying principals in reconfiguring radiation patterns, followed by the presentations of the implemented innovative antenna topologies to suit particular advanced features. The various adaptation techniques of radiation pattern reconfigurable planar antennas and the understanding of its antenna design approaches has been investigated for its radiation pattern enhancement. A variety of design configurations have also been critically studied for their compatibilities to be operated in the mid-band communication systems. The review provides new insights on pattern reconfigurable antenna where such antennas are categorized as beam steering antenna and beam shaping antennas where the operation modes and purposes are clearly investigated. The review also revealed that for mid-band 5G communication, the commonly used electronic switching such as PIN diodes have sufficient isolation loss to provide the required beam performance.
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PublicationSwitchable Beam Antenna with Five Planar Element using PIN Diode in Elevation Plane( 2020-09-28)This work focuses on the switchable beam parasitic patch antenna for the point to point communication system. This concept gives more flexibility due to their ability to modify the radiation and providing multiple functionalities. This work focuses on two points directly to minimize the number of PIN Diode and to maximize its reconfiguration capabilities. First, the concept of two parasitic element is addressed. The mutual coupling effect between both driven and parasitic has manage to steer the beam to-28{\mathrm{o}}, \ 0{\mathrm{o}} and +28o different angles in a single layer. The design consists of four parasitic elements with full ground and four pin diode switch HPND-4005, five different directions have been reached which are-450,-30{\mathrm{o}}, \ 0{\mathrm{o}}+30{\mathrm{o}} and +450. The parasitic patch antenna has achieved high gain of 8. 92dBi at 5.8 GHz with the beam ability to steer unti145o for both side of the parasitic element.
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PublicationHigher Order OAM Mode Generation Using Wearable Antenna for 5G NR Bands( 2023-01-01)This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum (OAM) waves with Mode +2 at 3.5 GHz (3.4 to 3.6 GHz) of the sub-6 GHz fifth-generation (5G) New Radio (NR) band. The proposed antenna is based on a uniform circular array of eight microstrip patch antennas on a felt textile substrate. In contrast to previous works involving the use of rigid substrates to generate OAM waves, this work explored the use of flexible substrates to generate OAM waves for the first time. Other than that, the proposed antenna was simulated, analyzed, fabricated, and tested to confirm the generation of OAM Mode +2. With the same design, OAM Mode −2 can be generated readily simply by mirror imaging the feed network. Note that the proposed antenna operated at the desired frequency of 3.5 GHz with an overall bandwidth of 400 MHz in free space. Moreover, mode purity analysis is carried out to verify the generation of OAM Mode +2, and the purity obtained was 41.78% at free space flat condition. Furthermore, the effect of antenna bending on the purity of the generated OAM mode is also investigated. Lastly, the influence of textile properties on OAM modes is examined to assist future researchers in choosing suitable fabrics to design flexible OAM-based antennas. After a comprehensive analysis considering different factors related to wearable applications, this paper demonstrates the feasibility of generating OAM waves using textile antennas. Furthermore, as per the obtained Specific Absorption Rate (SAR), it is found that the proposed antenna is safe to be deployed. The findings of this work have a significant implication for body-centric communications.
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PublicationWearable UHF RFID Antenna based Metamaterial( 2021-01-01)This paper presents the development a wearable RFID application that is flexible, compact, low-cost, and suitable for the human body. The study's main goal is to design, build, and test a small and flexible RFID wristband tag antenna with UHF RFID operating frequency at 910 MHz. The result shows a good radiation pattern and an almost ideal VSWR which 1.09. Thus, a wearable UHF RFID tag antenna is designed with a gain of -11.87 dB for bending analysis. The tag features a meander dipole antenna with two square split-ring resonators (SRR) cells. A meander dipole antenna with two square split-ring resonators (SRR) cells is featured on the tag. It's built on a 0.277mm thick photo paper substrate with a dielectric constant of 3.2 and a loss tangent of 0.05. The proposed antenna is then combined with an RFID tag (NXP SL3S1213 UCODE G2iL chip) with an impedance of 23-j224 to evaluate its performance in terms of reflection coefficient, antenna gain, and maximum reading range. The overall size of the antenna tag dimensions is 117 mm × 26 mm.
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PublicationMulti-Mode Yagi Uda Patch Array Antenna With Non-Linear Inter-Parasitic Element Spacing( 2023-01-01)A low-profile and broad steerable patch array antenna is presented. The improvement of the multi-directional functions from the broadside is very limited for the patch array antenna. In this work, the number of directional beams is enhanced by 40% using a novel approach, inter-parasitic element expansion technique and adopted only four PIN diode switches. Results in simulation and measurement have verified that the patch parasitic array antenna is capable -of generating seven beam patterns directed towards -52°, -30°, -10°, 0°, +10°, +30°, and +52° at the xz-plane. Applying the inter-parasitic element spacing's optimization and minimizing the switching circuitry using four RF PIN diodes on the parasitic elements have contributed to the gain achievement of more than 7 dBi.
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PublicationOrbital Angular Momentum Vortex Waves Generation Using Textile Antenna Array for 5G Wearable Applications( 2022-01-01)The development of wireless systems for fifth-generation technology (5G) has enabled the use of textile antennas for a wide range of applications, and it has now become one of the world's most in-demand technology. As the number of wireless devices and users increase, operators would need higher channel capacity to deliver better possible service to their customers. This paper presents the generation of Orbital Angular Momentum (OAM) vortex waves with mode 1 using a wearable textile antenna. OAM introduces a new scheme called Mode Domain Multiple Access (MDMA). OAM mode is an orthogonal mode with each mode carrying individual signals. Therefore, multiple signals can be sent using the same carrier frequency without additional resources. This allows the channel capacity and spectrum efficiency to be enhanced. The proposed antenna array comprises rectangular microstrip patch elements with an inset fed technique. Felt textile fabric was used as an antenna substrate. A carefully planned feeding phase shift network was used to excite the elements by supplying similar output energy at output ports with the required phase shift value. The generated OAM waves were confirmed by measuring the null in the boresight direction of their 2D radiation patterns as well as simulated phase distribution, intensity distribution and mode purity. The antenna covered portions of the 5G n77 band with a bandwidth of 81.7 MHz and an overall gain of 2.9 dBi. This is, to the best of our knowledge, the first work on generating OAM waves using a flexible textile material.
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PublicationHigh Gain Beam-Steerable Reconfigurable Antenna using Combined Pixel and Parasitic Arrays( 2021-01-12)This paper presents a pattern reconfigurable antenna for wide beam steering applications at the 9.5 GHz band. The beam steering performance is based on the combination of a Yagi-Uda antenna and its complimenting top pixel structure. The integration of this driven antenna element with its parasitic elements is capable of providing steering of up to ±40° (at -40°, 0° and +40°). However, with the added combination of a reconfigurable pixel array on top, the steering angle of the antenna can then be improved to -45°, 0° and +45°, and with measured gains of between 6.5 and 7.5 dBi. A factor critical in enabling the added beam steering capability is the control of the mutual coupling within the bottom antenna array and the top pixel layer. Results indicate that the proposed antenna could be useful for X-Band radar and other applications that require beam steering.