Koch Snowflake Fractal Antenna Design in the Deep Space Bands for a Constellation of Cubesat Explorers

This paper presents the design and simulation of a Koch curve fractal antenna, developed according to the second iteration of the Koch snowflake fractal for S-band, C-band, X-band and Ku-band. The simulated antenna shows good performance for the operating frequencies and desirable gain, bandwidth and VSWR parameters. Being a compact antenna, it has a size, geometry and characteristics that go in accord with the CubeSat’s structure standards. The antenna was fabricated on a 1.5 mm thick FR-4 substrate. The VSWR achieved values are lower than 1.4 for the frequencies used (2.1 GHz to 2.4 GHz and 7.4 GHz to 8.9 GHz) with a simulated omnidirectional radiation pattern. A maximum gain of 6.8 dBi was achieved. As this antenna works optimally in the S, C and X bands, it is adequate for deep space applications, especially in low-power consumption systems. This approach would be ideal for constellations of Cubesat explorers.

Modified Koch Fractal Antenna for Multi and Wideband Wireless Applications

This paper focuses on the design and development of modified Koch fractal antenna. Compared to traditional Koch curve antenna, the presented antenna possesses a greater number of frequency bands and better impedance matching. Furthermore, the bacterial foraging optimization (BFO) approach is implemented to enhance the impedance bandwidth. The developed technique has been verified by employing various numerical simulations. The design parameters generated from the optimization procedure have been utilized to manufacture the antenna and the respective experimental and simulated results compared. The measured results show that the designed antenna exhibits multi and wideband behavior, covering WLAN, WIMAX, and various other wireless applications.

Introdução à Geometria Fractal no Ensino Médio Técnico: Uma Abordagem com Programação Python

This work is inserted in the context of technical high school andit aimed to analyze the integration between the branches of FractalGeometry, Analytical Geometry and Computer Programming.For this purpose, we carried out a bibliographic search about whatcharacterizes and distinguishes Fractal Geometry from EuclideanGeometry, we also seek in our readings to list the most famousfractals. Then, we developed (in python language) several fractalgeneration programs. It was possible to work with amazing andeasily programmable fractal shapes, such as the Cantor Set, theHilbert Curve and Sierpinski Triangle. We also built two new familiesof fractal shapes from a generalization of the Koch Curve. Weconclude that programming fractals in the context of technical highschool is productive and challenging, as it requires many changesin the representations of fractal patterns.

Fractal Interpolation Using Harmonic Functions on the Koch Curve

The Koch curve was first described by the Swedish mathematician Helge von Koch in 1904 as an example of a continuous but nowhere differentiable curve. Such functions are now characterised as fractal since their graphs are in general fractal sets. Furthermore, it can be obtained as the graph of an appropriately chosen iterated function system. On the other hand, a fractal interpolation function can be seen as a special case of an iterated function system thus maintaining all of its characteristics. Fractal interpolation functions are continuous functions that can be used to model continuous signals. An in-depth discussion on the theory of affine fractal interpolation functions generating the Koch Curve by using fractal analysis as well as its recent development including some of the research made by the authors is provided. We ensure that the graph of fractal interpolation functions on the Koch Curve are attractors of an iterated function system constructed by non-constant harmonic functions.

A NOVEL 3D MICROMIXER WITH QUARTIC KOCH CURVE FRACTAL

In this paper, we mainly study the mixing performance of the micromixer with quartic Koch curve fractal (MQKCF) by numerical simulation. Changing the structure of the microchannel based on the fractal principle can significantly improve the fluid flow state in the microchannel and improve the mixing efficiency of the micromixer. This paper discussed the effects of different fractal deflection angles, microchannel heights and different fractal times on the mixing efficiency under four different Reynolds numbers (Re). It is found that changing the deflection angle of the fractal can bring extremely high benefits, which makes the fluid deflect and fold in the microchannel, enhancing the chaotic convection in the microchannel, and improve the mixing efficiency of the fluid. Under the reasonable arrangement of the quartic Koch curve fractal principle, it can give the micro-mixture more than 99% mixing efficiency. Based on the excellent mixing performance of MQKCF, it also has extremely high application value in the biochemical neighborhood.

Quantitative evaluation of eddy current distribution by relative entropy and cross entropy

Koch curve exciting coil of an eddy current probe can adjust the eddy current distributing in more directions at a small domain to enhance the sensitivity of eddy current probe for short defect detection. In this study, a relative entropy and a cross entropy of tangential intersection angle spectrum are proposed to evaluate the eddy current distributions in the different directions when the eddy current probe is positioned at different lift-off distances and excited by different exciting frequency alternative currents. The eddy current distributions induced by a circular and a fractal Koch curve exciting coils are analyzed by the two entropy indices. With the increasing of the lift-off distance or the decreasing of the exciting frequency, the eddy current distributions induced by the Koch curve exciting coil are close to those induced by the circular exciting coil.