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Öğe Dual-polarized wideband 5G N77 band slotted MIMO antenna system for next-generation smartphones(Institute of Electrical and Electronics Engineers Inc., 2024) Kiani, Saad Hassan; Münir, Mehr E.; Savcı, Hüseyin Şerif; Rmili, Hatem; Alabdulkreem, Eatedal; Elmannai, Hela; Pau, Giovanni; Alibakhshikenari, MohammadIn this work, a slotted wideband eight-element multiple-input multiple-output (MIMO) antenna system is presented, which covers the N77 (3.2-4.2 GHz) frequency band. The MIMO antennas are printed on a 0.8-mm-thick FR-4 substrate with dimensions of $150\times75$ mm2. The antennas are placed along the length and width of the printed circuit board (PCB). The arrangement of antenna elements offers pattern and polarization diversity, enhancing the smartphone's ability to receive signals from various directions. The wideband characteristics in the frequency range of 3.25-4.49 GHz are achieved by utilizing a T-slot and an inverted C-slotted stub together. The radiation and total efficiency are found to be >60% for all the MIMO elements. For enhanced isolation between antenna elements placed along the width of the PCB, a slot is introduced, which ensures an isolation of 14.5 dB. This helps achieve an envelope correlation coefficient (ECC) < 0.025, diversity gain (DG) >9.95 dB, and a maximum channel capacity (CC) of 40 bps/Hz. The performance of the MIMO antenna is also assessed in the presence of a human, and comparable results are observed. In addition, the examination of the specific absorption rate (SAR) confirms that it remains well within the safety margins when in proximity to humans.Öğe Future smartphone: MIMO antenna system for 5G mobile terminals(IEEE-Institute of Electrical and Electronics Engineers Inc., 2021) Abdullah, Mujeeb; Altaf, Ahsan; Anjum, Muhammad Rizwan; Arain, Zulfiqar Ali; Jamali, Abdul Aleem; Alibakhshikenari, Mohammad; Falcone, Francisco; Limiti, ErnestoIn this article, an inverted L-shaped monopole eight elements Multiple Input Multiple Output (MIMO) antenna system is presented. The multi-antenna system is designed on a low cost 0.8 mm thick FR4 substrate having dimensions of 136 x 68 mm(2) resonating at 3.5GHz with a 6dB measured bandwidth of 450MHz, and with inter element isolation greater than 15 dB and gain of 4 dBi. The proposed design consists of eight inverted L-shaped elements and parasitic L-shaped strips extending from the ground plane. These shorted stripes acted as tuning stubs for the four inverted L-shaped monopole elements on the side of chassis. This is done to achieve the desired frequency range by increasing the electrical length of the antennas. A prototype is fabricated, and the experimental results show good impedance matching with reasonable measured isolation within the desired frequency range. The MIMO performances, such as envelope correlation coefficient (ECC) and mean effective gain (MEG) are also calculated along with the channel capacity of 38.1bps/Hz approximately 2.6 times that of 4 x 4 MIMO system. Due to its simple shape and slim design, it may be a potential chassis for future handsets. Therefore, user hand scenarios, i.e. both single and dual hand are studied. Also, the effects of hand scenarios on various MIMO parameters are discussed along with the SAR. The performance of the proposed system in different scenarios suggests that the proposed structure holds promising future within the next generation radio smart phones.Öğe Isolation improvement in UWB-MIMO antenna system using slotted stub(MDPI, 2020) Altaf, Ahsan; Iqbal, Amjad; Smida, Amor; Smida, Jamel; Althuwayb, Ayman A.; Hassan Kiani, Saad; Alibakhshikenari, Mohammad; Falcone, Francisco; Limiti, ErnestoMultiple-input multiple-output (MIMO) scheme refers to the technology where more than one antenna is used for transmitting and receiving the information packets. It enhances the channel capacity without more power. The available space in the modern compact devices is limited and MIMO antenna elements need to be placed closely. The closely spaced antennas undergo an undesirable coupling, which deteriorates the antenna parameters. In this paper, an ultra wide-band (UWB) MIMO antenna system with an improved isolation is presented. The system has a wide bandwidth range from 2-13.7 GHz. The antenna elements are closely placed with an edge to edge distance of 3 mm. In addition to the UWB attribute of the system, the mutual coupling between the antennas is reduced by using slotted stub. The isolation is improved and is below -20 dB within the whole operating range. By introducing the decoupling network, the key performance parameters of the antenna are not affected. The system is designed on an inexpensive and easily available FR-4 substrate. To better understand the working of the proposed system, the equivalent circuit model is also presented. To model the proposed system accurately, different radiating modes and inter-mode coupling is considered and modeled. The EM model, circuit model, and the measured results are in good agreement. Different key performance parameters of the system and the antenna element such as envelope correlation coefficient (ECC), diversity gain, channel capcity loss (CCL) gain, radiation patterns, surface currents, and scattering parameters are presented. State-of-the-art comparison with the recent literature shows that the proposed antenna has minimal dimensions, a large bandwidth, an adequate gain value and a high isolation. It is worth noticeable that the proposed antenna has high isolation even the patches has low edge-to-edge gap (3 mm). Based on its good performance and compact dimensions, the proposed antenna is a suitable choice for high throughput compact UWB transceivers.Öğe Modified U-shaped resonator as decoupling structure in MIMO antenna(MDPI, 2020) Iqbal, Amjad; Altaf, Ahsan; Abdullah, Mujeeb; Alibakhshikenari, Mohammad; Limiti, Ernesto; Kim, SunghwanThis paper presents an isolation enhancement of two closely packed multiple-input multiple-output (MIMO) antenna system using a modified U-shaped resonator. The modified U-shaped resonator is placed between two closely packed radiating elements resonating at 5.4 GHz with an edge to edge separation distance of 5.82 mm (lambda(degrees)/10). Through careful adjustment of parametric modelling, the isolation level of -23 dB among the densely packed elements is achieved. The coupling behaviour of the MIMO elements is analysed by accurately designing the equivalent circuit model in each step. The antenna performance is realized in the presence and absence of decoupling structure, and the results shows negligible effects on the antenna performance apart from mutual coupling. The simple assembly of the proposed modified U-shaped isolating structure makes it useful for several linked applications. The proposed decoupling structure is compact in nature, suppress the undesirable coupling generated by surface wave and nearby fields, and is easy to fabricate.Öğe Multiple elements MIMO antenna system with broadband operation for 5th generation smart phones(IEEE-Institute of Electrical and Electronics Engineers Inc., 2022) Kiani, Saad Hassan; Iqbal, Amjad; Wong, Sai-Wai; Savcı, Hüseyin Şerif; Alibakhshikenari, Mohammad; Dalarsson, MarianaIn this work, a simple, low-cost, dual wideband sub6GHz Multiple Input Multiple Output (MIMO) antenna system for a smart phone is presented. The antenna system is fabricated using inexpensive and commercially easily available 0.8 mm thick FR4 substrate. The presented system consists of a single main board and two side boards containing eight antennas and feedings. The radiating elements are etched on the side boards to provide space for other electronic components and RF systems and sub systems. The dimensions of the main board and the two side boards are 150 x 75 x 0.8 mm(3) and 150 x 6 x 0.8 mm(3), respectively. The radiating elements are etched on the side substrates and the feeding network is designed on the main board. The proposed system resonates at 3.5 GHz and 5 GHz providing -10 dB bandwidth of 250 MHz (ranges from 3.3 GHz to 3.55 GHz) and 1700 MHz (ranges from 4.2 GHz to 6.2 GHz), respectively. The design and the arrangement of the structure enable pattern diversity and ensures at least -15 dB of isolation between any two given radiating elements. Moreover, various different key performance parameters such as envelope correlation coefficient (ECC), mean effective gain (MEG), channel capacity (CC), specific absorption rate (SAR), gain, and efficiency are also presented. It is found that the peak gain of the system is 5.8 dBi, ECC is lower than 0.015, efficiency ranges between 58% to 78%, peak SAR is 1.28 W/Kg, and the maximum CC is 40.2 bps/Hz within the frequency band of interest. In addition, to further demonstrate the usefulness of such structure as a smart mobile terminal, single and dual hand scenarios are also presented. To validate the concept and the computed results, a prototype is fabricated and measured. It is found that the simulated results are in very good agreement with the measured results. Based on the performance and the measured results, we believe that this structure holds a promising future within the next generation smart mobile phones.
