scholarly journals MIMO Reconfigurable Antennas for Wi-Fi 2.4 GHz Communication.

We are living in the era of wireless communication. From accessing Internet through smartphones and Wi-Fi, changing TV channels with remote controls, using wireless computer peripherals like mouse, keyboards and headphones to mobile body area networks for keeping track of heart rate, blood pressure and body temperature, applications of wireless communication is everywhere. The most frequent and common use of wireless communication is mobile phones or cellular phones which uses the radio waves to carry data from one place to another. Though there are many advantages of wireless communication which makes it so popular, there are two most significant challenges in implementing a wireless communication system: multipath propagation and limited information rate. The concept of multipath propagation refers to travelling of wireless signal to the receiving antenna via different paths in space resulting in inter-symbol interference and fading. This phenomenon leads to failure of maximum use of the bandwidth resulting in low information rate. The problematic event of multipath propagation can be exploited by using more than one antenna (MIMO) in the sending and the receiving side. Multiple sending antennas use the concept of space diversity by sending same data signal through different path based on the fact that different version of the same signal will be received by the receiver increasing quality and reliability of the received data signal.Though in the current usage scenario, MIMO actually exploits multipath propagation concept for carrying more than one data stream over the same radio signal. One of the most important factors that influence the efficiency of MIMO antenna systems is the design layout of multiple antennas. Microstrip antennas, having small height and width, low cost, low weight and small volume can be a suitable candidate for being used as MIMO. The wireless performance of locally limited wireless communication systems such as Bluetooth and Wi-Fi using 2.4 GHz unlicensed band can be increased significantly by incorporating the advantages of MIMO and microstrip antenna technology. In this paper, the performance of MIMO Microstrip antenna using OFDM technique for 2.4 GHz communication has been evaluated.

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1439
Author(s):  
Janghyuk Youn ◽  
Woong Son ◽  
Bang Chul Jung

Recently, reconfigurable intelligent surfaces (RISs) have received much interest from both academia and industry due to their flexibility and cost-effectiveness in adjusting the phase and amplitude of wireless signals with low-cost passive reflecting elements. In particular, many RIS-aided techniques have been proposed to improve both data rate and energy efficiency for 6G wireless communication systems. In this paper, we propose a novel RIS-based channel randomization (RCR) technique for improving physical-layer security (PLS) for a time-division duplex (TDD) downlink cellular wire-tap network which consists of a single base station (BS) with multiple antennas, multiple legitimate pieces of user equipment (UE), multiple eavesdroppers (EVEs), and multiple RISs. We assume that only a line-of-sight (LOS) channel exists among the BS, the RISs, and the UE due to propagation characteristics of tera-hertz (THz) spectrum bands that may be used in 6G wireless communication systems. In the proposed technique, each RIS first pseudo-randomly generates multiple reflection matrices and utilizes them for both pilot signal duration (PSD) in uplink and data transmission duration (DTD) in downlink. Then, the BS estimates wireless channels of UE with reflection matrices of all RISs and selects the UE that has the best secrecy rate for each reflection matrix generated. It is shown herein that the proposed technique outperforms the conventional techniques in terms of achievable secrecy rates.


2011 ◽  
Vol 143-144 ◽  
pp. 32-36
Author(s):  
Su Ling Wang ◽  
Ya Ting Gan ◽  
Guo Dong Wang

Microstrip Antennas have many applications in various communication systems. A new configuration of microstrip antenna is proposed in this paper. The microstrip antenna has two radiation ports. Through changing the radiation intensity of the two ports, the proposed structure breaks the balance of the radiation of the microstrip antenna therefore the radiation pattern would be changed corresponsively. Theory analysis is carried out based on microstrip antenna theory. Both analysis and simulation show that the new configuration can realize the radiation pattern controlled and the theory analysis agreed very well with simulation.


2016 ◽  
Vol 78 (5-9) ◽  
Author(s):  
Muhammad Fauzan Edy Purnomo ◽  
Hadi Suyono ◽  
Panca Mudjirahardjo ◽  
Rini Nur Hasanah

The circularly polarized (CP) microstrip antennas, both of singly- and doubly-fed types, possess inherent limitation in gain, impedance and axial-ratio bandwidths. These limitations are caused mainly by the natural resonance of the patch antenna which has a high unloaded Q-factor and the frequency-dependent excitation of two degenerative modes (TM01 and TM10) when using a single feed. Many applications which require circular polarization, large bandwidth, and good performance, especially in the field of wireless communication, are still difficult to be designed by using antenna software. Some consideration to take will include the application target and design specification, the materials to be used, and the method to choose (formula, numerical analysis, etc). This paper explains and analyzes the singly-fed microstrip antenna with circular polarization and large bandwidth. This singly-fed type of microstrip antenna provides certain advantage of requiring no external circular polarizer, e.g. the 900 hybrid, as it only needs to apply some perturbation or modification to a patch radiator with a standard geometry. The design of CP and large-bandwidth microstrip antenna is done gradually, by firstly truncating one tip, then truncating the whole three tips, and finally modifying it into a pentagonal patch structure and adding an air-gap to obtain larger bandwidths of impedance, gain and axial ratio. The last one antenna structure results in a novelty because it is a rare design of antenna which includes all types of bandwidth (impedance, gain, and axial ratio) being simultaneously larger than the origin antenna. The resulted characteristic performance of the 1-tip (one-tip) antenna shows respectively 1.9% of impedance bandwidth, 3.1% of gain bandwidth, and 0.45% of axial-ratio bandwidth. For the 3-tip (three-tip) step, the resulted bandwidths of respectively impedance, gain, and axial ratio are 1.7%, 3.3% and 0.5%. The pentagonal structure resulted in the bandwith values of 15.67%, 52.16% and 4.11% respectively for impedance, gain, and axial ratio. 


Electronics ◽  
2021 ◽  
Vol 10 (17) ◽  
pp. 2141
Author(s):  
Junghoon Cha ◽  
Choon-Seong Leem ◽  
Ikhwan Kim ◽  
Hakyoung Lee ◽  
Hojun Lee

In this study, we proposed an indoor broadband dual-polarized 2 × 2 MIMO (multiple-input and multiple-output) antenna having dimensions of 240 mm × 200 mm × 40 mm, for application in 5G wireless communication systems. The proposed antenna comprised two vertically polarized circular monopole antennas (CMAs), two horizontally polarized modified rectangular dipole antennas (MRDAs), and a ground plane. The distance between the two MRDAs (MRDA1 and MRDA2) was 70.5 mm and 109.5 mm in the horizontal (x-direction) and 109.5 mm vertical (y-direction) directions, respectively. Conversely, the distance between the two CMAs (CMA1 and CMA2) was 109.5 mm and 70.5 mm in the horizontal (x-direction) and vertical (y-direction) directions, respectively. While the CMAs achieved broadband characteristics owing to the optimal gap between the dielectric and the driven radiator using a parasitic element, the MRDAs achieved broadband owing to the optimal distance between the dipole antennas. The observations in this experiment confirmed that the proposed could operate in the 5G NR n46 (5.15–5.925 GHz), n47 (5.855–5.925 GHz), n77 (3.3–4.2 GHz), n78 (3.3–3.8 GHz), and the n79 (4.4–5 GHz) bands. Moreover, it exhibited a wide impedance bandwidth (dB magnitude of ) of 101% in the 2.3–7 GHz frequency range, high isolation (dB magnitude of ), low envelope coefficient correlation (ECC), gain of over 5 dB, and average radiation efficiency of 87.19%, which verified its suitability for application in sub-6 GHz 5G wireless communication systems.


Signals ◽  
2022 ◽  
Vol 3 (1) ◽  
pp. 29-37
Author(s):  
Muhammad Ikram

The current and future wireless communication systems, WiFi, fourth generation (4G), fifth generation (5G), Beyond5G, and sixth generation (6G), are mixtures of many frequency spectrums. Thus, multi-functional common or shared aperture antenna modules, which operate at multiband frequency spectrums, are very desirable. This paper presents a multiple-input and multiple-output (MIMO) antenna design for the 5G/B5G Internet of Things (IoT). The proposed MIMO antenna is designed to operate at multiple bands, i.e., at 3.5 GHz, 3.6 GHz, and 3.7 GHz microwave Sub-6 GHz and 28 GHz mm-wave bands, by employing a single radiating aperture, which is based on a tapered slot antenna. As a proof of concept, multiple tapered slots are placed on the corner of the proposed prototype. With this configuration, multiple directive beams pointing in different directions have been achieved at both bands, which in turn provide uncorrelated channels in MIMO communication. A 3.5 dBi realized gain at 3.6 GHz and an 8 dBi realized gain at 28 GHz are achieved, showing that the proposed design is a suitable candidate for multiple wireless communication standards at Sub-6 GHz and mm-wave bands. The final MIMO structure is printed using PCB technology with an overall size of 120 × 60 × 10 mm3, which matches the dimensions of a modern mobile phone.


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