Fractal antennas and arrays: a review and recent developments

2020 ◽  
pp. 1-25
Author(s):  
Anirban Karmakar
Keyword(s):  
Antenna Arrays ◽  
Fractal Geometry ◽  
Fractal Antenna ◽  
The Past ◽  
Model Complex ◽  
Recent Developments ◽  
Fine Structures ◽  
Self Similar ◽  
Fractal Antennas ◽  
Primary Focus

Abstract In mathematical definition, a fractal is a self-similar subset of Euclidean space whose fractal dimension strictly exceeds its topological dimension which in turn involves a recursive generating methodology that results in contours with infinitely intricate fine structures. Fractal geometry has been used to model complex natural objects such as clouds coastlines, etc., that has space-filling properties. In the past years, several groups of scientists around the globe tried to implement the structure of fractal geometry for applications in the field of electromagnetism, which led to the development of new innovative antenna configurations called “fractal antennas” which is primarily focused in fractal antenna elements, and fractal antenna arrays. It has been demonstrated that by exploiting the recursive nature of fractals, several marvellous kinds of properties can be observed in antennas and arrays. The primary focus of this article is to provide a compressed overview of the developments in fractal-shaped antennas as well as arrays over the last few decades where the most prominent contributions mostly from IEEE journals have been highlighted. The open intention of this review work is to show an encouraging path to antenna researchers for its advancement using fractal geometries.

scholarly journals Sierpinski carpet fractal monopole antenna for ultra-wideband applications

2022 ◽  
Vol 12 (1) ◽  
pp. 983
Author(s):  
Medhal Bharathraj Kumar ◽  
Praveen Jayappa
Keyword(s):  
Microstrip Antenna ◽  
Monopole Antenna ◽  
Ultra Wideband ◽  
Base Case ◽  
Fractal Antenna ◽  
Sierpinski Carpet ◽  
Low Profile ◽  
Self Similar ◽  
Fractal Antennas ◽  
Sierpiński Carpet

Microstrip antenna is broadly used in the modern communication system due to its significant features such as light weight, inexpensive, low profile, and ease of integration with radio frequency devices. The fractal shape is applied in antenna geometry to obtain the ultra-wideband antennas. In this paper, the sierpinski carpet fractal monopole antenna (SCFMA) is developed for base case, first iteration and second iteration to obtain the wideband based on its space filling and self-similar characteristics. The dimension of the monopole patch size is optimized to minimize the overall dimension of the fractal antenna. Moreover, the optimized planar structure is proposed using the microstrip line feed. The monopole antenna is mounted on the FR4 substrate with the thickness of 1.6 mm with loss tangent of 0.02 and relative permittivity of 4.4. The performance of this SCFMA is analyzed in terms of area, bandwidth, return loss, voltage standing wave ratio, radiation pattern and gain. The proposed fractal antenna achieves three different bandwidth ranges such as 2.6-4.0 GHz, 2.5-4.3 GHz and 2.4-4.4 GHz for base case, first and second iteration respectively. The proposed SCFMA is compared with existing fractal antennas to prove the efficiency of the SCFMA design. The area of the SCFMA is 25×20 mm<sup>2</sup>, which is less when compared to the existing fractal antennas.

scholarly journals Performance analysis of first iteration koch curve fractal log periodic antenna of varying flare angles

2013 ◽  
Vol 3 (1) ◽  
Author(s):  
Ashutosh Singh ◽  
Reneez Kabeer ◽  
Z. Ali ◽  
V. Singh ◽  
M. Shukla
Keyword(s):  
Performance Analysis ◽  
Fractal Geometry ◽  
Return Loss ◽  
Broad Band ◽  
Fractal Antenna ◽  
Recent Past ◽  
Koch Curve ◽  
Log Periodic Antenna ◽  
Simulation Results ◽  
Fractal Antennas

AbstractMiniaturization has always been a crucial challenge in the field of antenna engineering. In the recent past a number of researchers have shown that fractal geometry have potential to design smaller, broad band and multi band antennas. In this proposed work performances of log periodic fractal antennas of different flare angles have been investigated. Simulation results show that fractal log periodic antenna gives better performance in terms of gain, return loss and directivity. Performance of log periodic fractal antenna has also been investigated for flare angles 30°, 45°, 60°, 70° and 80°. In this proposed work fractal antenna gives best performance with 60° flare angle.

scholarly journals A novel compact stair-shaped multiband fractal antenna for wireless communication systems

2021 ◽  
Vol 72 (5) ◽  
pp. 306-314
Author(s):  
Zain ul Abidin Jaffri ◽  
Zeeshan Ahmad ◽  
Asif Kabir ◽  
S. Sabahat ◽  
H. Bukhari
Keyword(s):  
Fractal Geometry ◽  
Communication Systems ◽  
Data Communication ◽  
Wireless Communication Systems ◽  
Fractal Antenna ◽  
Multiple Frequency ◽  
Radiation Characteristics ◽  
The Third ◽  
Self Similar ◽  
Good Agreement

Abstract The growing demand for enhanced capacities, broadband services, and high transmission speeds to accommodate speech, image, multimedia, and data communication simultaneously puts a requirement for antenna to operate in multiple frequency bands. A novel compact fractal antenna based on self-similar stair-shaped fractal geometry is proposed in this paper. The fractal antenna is designed by modifying the patch antenna through the iterative process using stair-shaped fractal geometry. The third iteration results in a tri-band response, and the antenna resonate at 3.65, 4.825, and 6.325 GHz with impedance bandwidths of 75.6, 121.2, and 211.4 MHz, respectively. The antenna is designed in CST Microwave studio, and evaluated for operating bands and radiation characteristics. Prototype for the third iteration of the fractal antenna is fabricated on FR-4 substrate which is further tested for measured operating bands and radiation characteristics. The simulated and measured results show good agreement.

scholarly journals Fractal Antennas for Wireless Communications

2020 ◽  
Author(s):  
Amer T. Abed ◽  
Mahmood J. Abu-AlShaer ◽  
Aqeel M. Jawad
Keyword(s):  
Fractal Geometry ◽  
Surface Current ◽  
Axial Ratio ◽  
Experimental Measurements ◽  
Fractal Antenna ◽  
Limited Size ◽  
Low Profile ◽  
Radiation Properties ◽  
Stage Process ◽  
Fractal Antennas

When the length of the antenna is less than a quarter of the wavelength of the operating frequency, good radiation properties are difficult to obtain. However, size limitations can be overcome in this case using a fractal geometry antenna. The shape is repeated in a limited size such that the total length of the antenna is increased to match, for example, half of the wavelength of the corresponding desired frequency. Many fractal geometries, e.g., the tree, Koch, Minkowski, and Hilbert fractals, are available. This chapter describes the details of designing, simulations, and experimental measurements of fractal antennas. Based on dimensional geometry in terms of desired frequency bands, the characteristics of each iteration are studied carefully to improve the process of designing the antennas. In depth, the surface current distribution is investigated and analyzed to enhance the circular polarization radiation and axial ratio bandwidth (ARBW). Both, simulation and experimental, results are discussed and compared. Two types of fractal antennas are proposed. The first proposed fractal antenna has a new structure configured via a five-stage process. The second proposed fractal antenna has a low profile, wherein the configuration of the antenna was based on three iterations.

What’s Good for George Sánchez Is Good for Boyle Heights: Regenerative Scholarship, Urban Racism, Gentrification, and East LA Interchange

2017 ◽  
Vol 4 (2) ◽  
Author(s):  
Gilbert Estrada
Keyword(s):  
Working Class ◽  
Urban Pollution ◽  
Metropolitan Regions ◽  
The Past ◽  
Award Winning ◽  
Boyle Heights ◽  
Good For ◽  
Primary Focus ◽  
Deed Restrictions ◽  
Class Community

The inclusive ideals of George Sánchez have helped shape a new generation of academics who have promoted connections with nonacademic organizations. This article discusses how Sánchez has continued these efforts through his pivotal contributions to an award-winning documentary focusing on the multiethnic, working-class community of Boyle Heights: Betsy Kalin’s film East LA Interchange (2015). East LA Interchange’s greatest contribution to the generative scholarship Sánchez emphasizes is its critical analysis of modern urban problems, utilizing history as a tool for social change. The story of Boyle Heights is not just a history of a single working-class community with a diverse culture. It is also a tale of a neighborhood trying to solve real world problems such as gentrification, unaffordable housing, community displacement, and urban pollution. The film portrays these difficulties in the present while showing that they originated decades ago. Sánchez and East LA Interchange are at their best when they provide the historical contexts of contemporary problems, emphasizing that history is not only the study of the past. Rather, history is the unending dialogue between the past, present, and future, and any significant discourse on today’s urban ills must be rooted in the past. For students and others interested in the diverse communities common in many US metropolitan regions, East LA Interchange has much to offer regarding the issues of immigration, redlining, deed restrictions, political activism, freeway construction, living with racially and ethnically diverse community members, and the nationwide problem of gentrification. These themes, especially gentrification, are the primary focus of this article.

Wilfred Ethier. Modern International Economics. New York: W. W. Norton and Company. 1983. xviii + 588 pp.

1988 ◽  
Vol 27 (1) ◽  
pp. 81-83
Author(s):  
Nadeem A. Burney
Keyword(s):  
International Economic ◽  
New York ◽  
Economic Theory ◽  
International Economics ◽  
International Monetary System ◽  
International Markets ◽  
The Past ◽  
Monetary System ◽  
Recent Developments

Its been long recognized that various economies of the world are interlinked through international trade. The experience of the past several years, however, has demonstrated that this economic interdependence is far greater than was previously realized. In this context, the importance of international economic theory as an area distinct from general economics hardly needs any mentioning. What gives international economic theory this distinction is international markets for some goods and effects of national sovereignty on the character of economic activity. Wilfred Ethier's book, which incorporates recent developments in the field, is an excellent addition to textbooks on international economics for one- or twosemester undergraduate courses. The book mostly covers standard topics. A distinguishing feature of this book is its detailed analysis of the flexible exchange rates and a discussion of the various approaches used for their determination. Within each chapter, the author has extensively used facts, figures and major events to clarify the concepts in the light of the theoretical framework. The book also discusses, in a fair amount of detail, the existing international monetary system and the role of various international organizations.

Developments in sugarcane processing over the past 15 years

2019 ◽  
pp. 451-458
Author(s):  
Peter W. Rein
Keyword(s):  
Environmental Conditions ◽  
Energy Value ◽  
The Past ◽  
Recent Developments ◽  
Technology Of Production ◽  
Sugarcane Processing

Developments in the technology of production of sugar from sugarcane tend to be incremental improvements in an effort to reduce costs and boost revenue. Nonetheless the developments are significant and contribute to sustainable sugarcane enterprises. Some technologies have adapted to changing environmental conditions, and more attention is being given to boosting revenue through associated activities, particularly in enhancing the potential for sugarcane operations to exploit the energy value of sugarcane. This paper outlines recent developments of interest in processing sugarcane.

Performing States-Of-In-Between: Dogs, Parrots, and Other Humans in Recent Austrian Performances

2017 ◽  
Vol 40 (3) ◽  
pp. 295-310
Author(s):  
Sabine Wilke
Keyword(s):  
Fine Arts ◽  
Specific Form ◽  
Cultural Critique ◽  
Contemporary Society ◽  
Dramatic Effect ◽  
The Past ◽  
Violent Content ◽  
The World ◽  
The Sixties ◽  
Recent Developments

Every late spring since 1951, the Wiener Festwochen bring performers from around the world to Vienna for an opportunity to share recent developments in performance styles and present them to a Viennese public that seems to be increasingly open to experimentation. These festival weeks solidify a specific form of Viennese self-understanding and self-representation as a culture that is rooted in performance. This essay seeks to link two recent Austrian performances—one of them was part of the Wiener Festwochen in 2016, the other was staged in downtown Linz during the past few years—to this Austrian and specifically Viennese culture of performance by reading them as contemporary articulations of a tradition of radical performance art that can be traced back to the Viennese Actionism of the sixties and later feminist articulations in the seventies and eighties. They play on the dramatic effect of these actions, specifically their joy in cruelty, chaos, and orgiastic intoxication, by staging regressions and thus making visible what has been dammed up and repressed in contemporary society.1 Just as their historical models, these two performances merge the performing and the fine arts and they highlight provocative, controversial, and, at times, violent content. But they do it in an interspecies context that adds an entire layer of complexity to the project of societal and cultural critique.

The Medicinal Chemistry of Therapeutic Peptides: Recent Developments in Synthesis and Design Optimizations

2019 ◽  
Vol 26 (13) ◽  
pp. 2330-2355 ◽  
Author(s):  
Anutthaman Parthasarathy ◽  
Sasikala K. Anandamma ◽  
Karunakaran A. Kalesh
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Therapeutic Potential ◽  
The Past ◽  
Recombinant Production ◽  
Tremendous Progress ◽  
Recent Developments ◽  
Therapeutic Peptides ◽  
Development Processes ◽  
Delivery Strategies

Peptide therapeutics has made tremendous progress in the past decade. Many of the inherent weaknesses of peptides which hampered their development as therapeutics are now more or less effectively tackled with recent scientific and technological advancements in integrated drug discovery settings. These include recent developments in synthetic organic chemistry, high-throughput recombinant production strategies, highresolution analytical methods, high-throughput screening options, ingenious drug delivery strategies and novel formulation preparations. Here, we will briefly describe the key methodologies and strategies used in the therapeutic peptide development processes with selected examples of the most recent developments in the field. The aim of this review is to highlight the viable options a medicinal chemist may consider in order to improve a specific pharmacological property of interest in a peptide lead entity and thereby rationally assess the therapeutic potential this class of molecules possesses while they are traditionally (and incorrectly) considered ‘undruggable’.

scholarly journals Bio-Based Alternatives to Phenol and Formaldehyde for the Production of Resins

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2237 ◽  
Author(s):  
P. R. Sarika ◽  
Paul Nancarrow ◽  
Abdulrahman Khansaheb ◽  
Taleb Ibrahim
Keyword(s):  
Raw Materials ◽  
Phenol Formaldehyde ◽  
Raw Material ◽  
Wood Industry ◽  
Suitable Material ◽  
The Past ◽  
Wide Range ◽  
Recent Developments ◽  
Sustainable Materials ◽  
Materials Used

Phenol–formaldehyde (PF) resin continues to dominate the resin industry more than 100 years after its first synthesis. Its versatile properties such as thermal stability, chemical resistance, fire resistance, and dimensional stability make it a suitable material for a wide range of applications. PF resins have been used in the wood industry as adhesives, in paints and coatings, and in the aerospace, construction, and building industries as composites and foams. Currently, petroleum is the key source of raw materials used in manufacturing PF resin. However, increasing environmental pollution and fossil fuel depletion have driven industries to seek sustainable alternatives to petroleum based raw materials. Over the past decade, researchers have replaced phenol and formaldehyde with sustainable materials such as lignin, tannin, cardanol, hydroxymethylfurfural, and glyoxal to produce bio-based PF resin. Several synthesis modifications are currently under investigation towards improving the properties of bio-based phenolic resin. This review discusses recent developments in the synthesis of PF resins, particularly those created from sustainable raw material substitutes, and modifications applied to the synthetic route in order to improve the mechanical properties.

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