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The design of Massive MIMO Antennas presents challenges due to their large size, which can impede the design process. Additionally, the arrangement of multiple antenna elements in Massive MIMO Antennas poses a challenge, as it surpasses the capabilities of simulation software and involves complex procedures. Therefore, to address these issues, a scalability technique utilizing array factor theory is employed to determine the relationship between the configuration of MIMO antennas and the corresponding values of gain and half-power beamwidth (HPBW). By utilizing a simpler MIMO Antenna array with incremental configurations, such as 2x2, 4x4, 8x8, and 16x16 MIMO element schemes, the array factor theory allows for the prediction of the gain and HPBW values for a Massive MIMO Antenna array with a specific configuration. This research aims to explore the scalability process and derive equations that relate the gain and HPBW values to the different MIMO configurations. The designed MIMO antenna arrangement is based on rectangular antennas with truncated corners and circular antennas with X slots, allowing for the investigation of various configurations operating at a frequency of 3.5 GHz.

This paper presents a comprehensive review of the advancements and challenges in scalable modular antenna arrays for 5G Massive MIMO (Multiple Input Multiple Output) networks, a pivotal technology for the next-generation wireless communication. Tracing the evolution of wireless technologies from 1G to 4G, the paper contextualizes the paradigm shift brought by 5G, characterized by enhanced spectral efficiency, massive device connectivity, and higher frequency bands. Focusing on Massive MIMO, the paper explores its role in augmenting network capacity and signal quality via advanced techniques like beamforming and spatial multiplexing. It delves into the intricacies of designing and implementing scalable modular antenna arrays, essential for the flexibility and optimization of rapidly evolving 5G networks. The review also covers mathematical modeling, advantages of Massive MIMO, and the challenges in integration, performance under diverse conditions, and cost-complexity balance. Concluding with insights into the commercialization trajectory of MIMO technology and its integration into modern telecommunications, the paper highlights the ongoing research directions and future potential of scalable modular antenna arrays in meeting the ambitious demands of 5G and beyond.

This article presents a hybrid metasurface split beam antenna for fifth-generation (5G) mobile applications at 3.5 GHz. Multi-beam antennas with high directivity are required for a 5G mobile network. It can be achieved by having an array antenna. Using an antenna array at low frequency increases the complexity and size of the whole network. Therefore, a metasurface (MS) is proposed to direct surface current and to have high gain and multibeam properties. To achieve that, a square split ring resonator (SSRR) and U-shaped unit cell metasurface is implemented as a superstrate to a single square patch antenna. The manipulation of this hybrid metasurface configuration can create opposite current flow on the unit cell and thus split the beam. The hybrid metasurface superstrate and antenna are fabricated on FR-4 ( $\varepsilon \text{r}\,\,=4.4$ , tan $\delta =0.02$ ). Results show that the antenna resonates well at 3.5 GHz, with a less than −10 dB reflection coefficient. The arrangement of the unit cells on the superstrate metasurface is able to split the current, and thus the radiation pattern beam is split into two beams in the E-plane at ± 45°. This antenna is a good candidate for future 5G Pico cell base stations in urban or suburban areas with high capacity and interferences.

This paper aims to produce a high data capacity and miniaturized flexible chipless RFID tag based on the frequency signature using the Modified Complementary Split Ring Resonator (MCSRR). The proposed 19 bits chipless RFID tag using the frequency shifting technique consists of five slotted overlaying MCSRR with Different Width (MCSRR with DW) structures and the dimension of 48 mm × 48 mm. The structure is designed by using a flexible (Polyethylene Terephthalate) PET substrate with permittivity of 0.2. The operating frequency is between 0.9 GHz and 2.7 GHz. The advancement of slotted overlaying MCSRR with DW structures has successfully miniaturized the chipless RFID tag structure to about 107 mm2/ bit, 0.02λmid2/bit and 0.09 GHz/bit by maximizing the number of resonators in a limited space and minimizing the frequency separation between the resonators. The omnidirectional tag antenna is incorporated with the proposed MCSRR structure using the retransmission measurement method. The log-periodic antenna with a gain of 5-7 dBi is used for this measurement to improve the range distance between tag and reader system. Based on the retransmission measurement involving the antenna tag, the 19 bits chipless RFID tag which consists of five MCSRR with DW structures can be detected with a maximum range distance of 30 cm and a power transmitted level of 30 dBm.

One of the challenges of antenna development for wireless communication systems is to create an antenna that can be operated in wide frequency so that a single antenna can be used in various wireless communication technologies. This paper discussed the wideband antenna with Telkom University Logo-shaped patch, using Fr-4 (?r = 4.3) substrate with 1.6 mm thickness. The antenna can be operated in the frequency range of 760 MHz – 13.75 GHz. The gain performance at the working frequency is still above 0 dBi. Hence, the antenna design to work properly for wireless communication systems which require relatively long distances. The Defected Ground Substrate (DGS) method is applied to achieve that bandwidth. Measurement shows the logo-shaped patch antenna achieves 12.994 GHz bandwidth with 1.33 VSWR and gain 2.85 at 921.5 MHz frequency.

Penyerap gelombang elektromagnetik (GEM) berbentuk planar mulai banyak diteliti dalam dekade terakhir. Dengan bentuknya yang tipis, fleksibel, dan mudah untuk difabrikasi membuat penyerap GEM berpotensi untuk digunakan pada teknologi baru di masa depan. Salah satu bentuk yang memiliki penyerapan yang baik adalah menggunakan Split Ring Resonator (SRR). Pada makalah ini, absorber berbentuk patch persegi, Axially Symmetric SRR (AS-SRR), dan Axially Asymmetric SRR (AAS-SRR) didesain dan diamati pada C-Band. Dari hasil simulasi didapatkan ukuran sel persegi sebesar 30 mm, AS-SRR sebesar 20 mm, dan AAS-SRR sebesar 18 mm. Ketiga bentuk tersebut menghasilkan penyerapan di atas 92% dengan bandwidth masing-masing 0,055 GHz, 0,076 GHz, dan 0,081 GHz. Selanjutnya, dilakukan karakterisasi terhadap parameter desain AAS-SRR dan didapatkan parameter yang paling memengaruhi bandwidth dan frekuensi resonansi adalah panjang resonator dan tebal resonator. Bandwidth maksimal dari karakterisasi sebesar 0,087 GHz.

In this work, wearable resistive gas sensors based on hybrid graphene/zinc oxide (ZnO) nanocomposites were fabricated on a flexible cotton fabric and employed to monitor odorless and colorless carbon monoxide (CO). Dip-coating and chemical bath deposition (CBD) was used to deposit the graphene layer and grow the ZnO nanorods, respectively. The films were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-Ray diffraction (XRD) to investigate their morphological structures, elemental composition, and crystal phase, respectively. Those characterizations were also confirming the growth of ZnO nanorods on the already-deposited graphene layer on fabrics. From the gas sensor measurements at room temperature, it was revealed that these graphene/ZnO nanocomposites were highly sensitive and selective towards CO gas at low concentration down to 10 ppm. The shortest response and recovery times of the sensors were measured to be 280 s and 45 s, respectively. Moreover, in comparison to bare graphene sensors, the surface modification by ZnO nanorods could obviously enhance the sensing response by up to 40% (i.e., doubled sensitivity). These flexible hybrid sensors are therefore expected to be a promising alternative for the existing rigid CO sensors in the market by offering unique nanostructures, low-cost fabrication, high flexibility, and good sensing performances.

The telecommunication has a tremendous improvement in terms of data rates and bandwidth requiring sufficient frequency allocation and wideband spectrum availability. The millimeter-wave frequency band is one of the solution to these requirements, however communications in this band is facing new challenges on the climate effect to the channel propagation In this paper, we propose a 5G channel model considering the effect of humidity based on the characteristic of the natural environment of Palembang city. The channel model is represented by power levels and delay called a Power Delay Profile (PDP and is derived based on a series of computer simulations using parameters of nature in Palembang. The 5G channel model is important to further derive the outage performance to be used as the theoretical performance of 5G in Palembang since the the Shannon Channel Capacity Theorem is involved in the derivation. We conduct a series of computer simulations to evaluate the validity of the proposed channel model and its characteristics. We found that humidity affect to the performances, where high humidity makes the performances of outage and BER slightly worse, although the effect may be ignored for some applications. The results of this paper are expected to be the references for the development and implementation of 5G Networks especially at the mm-Wave band in Palembang.

This study presented the development of the bowtie antenna system design as the transmitter in the Ground Penetrating Radar (GPR) system. The Artificial Magnetic Conductor (AMC) reflector was integrated into the antenna system as a ground plane to obtain a high gain, increase bandwidth and produce a low-profile antenna. The antenna is designed to work at a center frequency of 2.1 GHz with a range of 1.6 - 2.6 GHz and has ultrawideband (UWB) characteristics with a fractional bandwidth of ≥ 25%. In addition, the value of late-time ringing must also be reduced to -30 dB to prevent masking effects on the detected object. Antenna modeling and simulation was done to obtain the optimum prototype design. Bowtie antenna realization was carried out using RT Duroid 5880 as a substrate with dielectric constant (εr) = 2.2 and thickness (h) = 1.57 mm. The AMC reflector was fabricated with FR-4 Epoxy substrate with a dielectric constant (εr) = 4.4 and thickness (h) = 1.6 mm. The antenna realization results show that the antenna has bandwidth = 510 MHz, return loss = -15.17 dB and VSWR = 1.15. The AMC integrated bowtie antenna radiation pattern produces a unidirectional pattern with gain = 4.2 dB. However, the ringing level becomes high by -19.18 dB. Further development is needed to achieve ringing level values that meet the GPR antenna system specifications.

ABSTRAK Siaran TV digital umumnya menggunakan antena tipe Yagi dan Kubikal yang berukuran besar sehingga tidak fleksibel digunakan di dalam ruangan. Penelitian ini merancang dan merealisasikan antena mikrostrip miniaturisasi fraktal Köch agar dimensi antena lebih kecil dan bandwidth lebih besar sehingga cocok digunakan di dalam ruangan. Miniaturisasi antena berupa fraktal Köch iterasi-1 pada patch dan teknik slot iterasi-2 pada ground plane menggunakan pencatuan mikrostrip proximity coupled feed pada alokasi frekuensi TV digital Indonesia 478 – 694 MHz dengan bandwidth 216 MHz. Antena dirancang pada software perancang antena, direalisasikan, diukur, dan diaplikasikan pada TV digital. Hasil simulasi antena menunjukkan bandwidth yang lebih besar dari spesifikasi yaitu 245,99 MHz pada rentang frekuensi 477,81 – 723,8 MHz. Return loss dan gain untuk direalisasikan sebesar -16,67 dB dan 3,085 dB pada frekuensi tengah 586 MHz. Pola radiasi berbentuk bidirectional dan polarisasi berbentuk linier. Panjang dan lebar antena hasil realisasi 17,33 cm X 17,33 cm. Kata Kunci: TV digital, antena, mikrostrip, Fraktal, Köch ABSTRACT Digital TV broadcasting generally uses large Yagi and Cubical type antennas, so it is not flexible to be used indoor. This study designs and applies miniaturization of Köch fractal microstrip antennas to obtain smaller dimensions and larger bandwidth. The miniaturization of antenna are Köch fractal iteration-1 on patch and iteration-2 slot technique on ground plane using proximity coupled feed at frequency allocation 478 – 694 MHz and the bandwidth is 216 MHz. The antenna was designed in software and developed, measured, and applied to digital TV. Antenna simulation results show a greater bandwidth than specification, 245.99 MHz, at the frequency range of 477.81 – 723.8 MHz. Return loss and gain simulation results that meet the specifications to be applied to digital TV antennas are -16.67 and 3.085 dB at 586 MHz center frequency. The radiation pattern is bidirectional and polarization is linear. The length and width dimensions of the antenna is 17.33 cm × 17.33 cm. Keywords: TV digital, antenna, microstrip, Fractal, Köch