Numerical synthesis of filtering antennas

Dizertační práce je zaměřena na kompletní metodiku návrhu tří a čtyř prvkových flíčkových anténních řad, které neobsahují žádné filtrující části a přesto se chovají jako filtrující antény (filtény). Návrhová metodika kombinuje přístup pro návrh filtrů s přístupem pro anténní řady a zahrnuje tvarování frekvenčních odezev činitele odrazu a normovaného realizovaného zisku. Směr hlavního laloku přes pracovní pásmo je kontrolován také. S cílem kontrolovat tvary uvedených charakteristik, nové gi koeficienty jsou představeny pro návrh filtrujících anténních řad. Návrhová metodika byla ověřena na tří a čtyř prvkové filtrující anténní řadě přes frekvenční pásmo od 4,8 GHz do 6,8 GHz, pro šířku pásma celé struktury od 7 % do 14 % a pro požadovanou úroveň činitele odrazu od –10 dB do –20 dB. Celá metodika byla podpořena výrobou a měřením šesti testovacích vzorků filtrujících anténních řad s rozdílnými konfiguracemi. Ve všech případech se simulované a naměřené výsledky dobře shodují.The dissertation thesis is focused on a complete design methodology of a three and four-element patch antenna arrays which are without any filtering parts and yet behave like a filtering antenna (filtenna). This design combines filter and antenna approaches and includes shaping the frequency response of the reflection coefficient and the modelling of the frequency response of the normalized realized gain. The frequency response of the main lobe direction is controlled as well. In order to control the shape of these responses, a set of gi coefficients for designing the filtering antenna array are obtained. The design methodology was verified on the three-element and four-element filtennas over the frequency range from 4.8 GHz to 6.8 GHz; for fractional bandwidth from 7 % to 14 % and for level of the reflection coefficient from –10 dB to –20 dB. The whole design methodology was supported by manufacturing and measuring six test cases of the filtering antenna array with different configurations. Simulated and measured results show a good agreement in all cases.

Design of Optimized Koch Based Fractal Patch Antenna for Multiband Wireless Applications

An optimized Koch based fractal patch antenna with twin lower leafs has been designed for appropriate wireless communication applications and capable of exhibiting penta-band behavior. The proposed structure has been created by introducing modified Koch curve on a rhombus shaped fractal patch having compact dimensions of 60 mm×50 mm×1.6 mm with defected ground structure. The reflection coefficient (S11) values of the proposed antenna are -11.97 dB, -20.29 dB, - 25.38 dB, -13.91 dB and -23.48 dB at resonating frequencies of 2.8649 GHz, 6.3514 GHz, 7.1622 GHz, 8.2973 GHz, and 8.9459 GHz, respectively. It has values of VSWR at all resonating frequencies within acceptable range of 1 to 2. The prototype of the proposed structure has been designed on easily available and low cost FR4 epoxy substrate material. The bandwidths of 1.39 GHz, 3.30 GHz, 10.19 GHz, 1.93 GHz and 2.23 GHz has been obtained at all resonating frequencies. The measured results has been analyzed and compared with simulated results and bears a close approximation. The developed prototype can be utilized for applications in S, C, and X frequency band which can further be used for various communication applications like radar, satellite communication and wireless computer networks

Multiband Antennas Design Techniques for 5G Networks: Present and Future Research Directions

With the development of wireless communication system has demanded compact wireless devices that allow more space to integrate the other electronics components. Advancement in technology creates challenges in implementing antenna for multiple RF band with a wide range of frequencies. With the advancement of optimization technique we can improve the antenna design as well as provide us the motivation of analyzing the existing studies in order to categorize and synthesize them in a meaningful manner. The objective of this paper contributes in two ways. First, it provides the research and development trends and novel approaches in design of multiband MIMO, smart reconfigurable and defected ground structure (DGS) antenna techniques for wireless system. Secondly, it highlights unique design issue reported in literature. The proposed paper aim is filling the gap in the literature and providing the researcher a useful reference

Fractal Geometry: An Attractive Choice for Miniaturized Planar Microwave Filter Design

Various fractal geometries are characterized by the self-similarity and space-filling properties. The space-filling feature has been successfully applied to design multiband antenna structures for a wide variety of multifunction wireless systems. On another hand, the second feature has proved its validity to produce miniaturized antennas and passive microwave circuits including the band-pass filters (BPF). This chapter demonstrates the design of miniaturized microstrip BPFs that are derived from fractal-based DGS resonators. Many microstrip BPFs based on the Minkowski fractal DGS resonators will be presented together with those based on Moore and Peano fractal geometries. Simulation results, of all of the presented BPFs, show that an extra-size reduction can be obtained as the iteration level becomes higher. Measured and simulated results agree well with each other. A comparison has been conducted with other filters based on Peano and Hilbert fractal geometries. The results reveal that the proposed BPF offers acceptable performance and a significant decrease of higher harmonics

Performance investigation of vertical axis wind turbine with savonius rotor using Computational Fluid Dynamics (CFD)

The quest of clean and sustainable energy has grown rapidly all over the world in the recent years. Among the renewable energy resources available, wind energy is considered one of the reliable, environmentally friendly, green and fastest-growing source of electricity generation. This generation is accomplished through wind turbines. However, the efficiency of these wind turbines is still very limited and unsatisfactory. The primary goal of this study is to evaluate the performance of a Savonius rotor wind turbine in terms of aerodynamic characteristics, including torque, torque coefficient, and power coefficient. The design of Savonius wind turbine blades is varied and its effects is observed. The simulation models are developed using a modeling software known as Solidworks 2021 and then generated into Ansys Design Modeler 2021 R1 to define the fluid domain. In total, three distinct turbine blades are modelled while varying the diameter and height of the rotor. The simulation study is performed using FLUENT 2021 R21. A constant wind speed value of 9.2 m/s has been used throughout the simulation. The simulation was carried out using a transient time flow with a constant upstream wind speed. The results have shown that the power coefficient of all models increases with TSR and the highest efficiency is consensually obtained at almost a unity (0.9) TSR. Comparing the performance of all models, Model 2 generates the highest power coefficient followed by Model 3 and Model 1, respectively. In terms of power, torque and torque coefficient, nearly similar conclusion is drawn

An Overview on Defected Ground Structure in Aspect of Microstrip Patch Antenna

Micro strip patch antenna has gained a lot of attention now a day, only because of their attractive features like small size, low profile, low manufacturing cost and easy to integrate with other microwave circuits, but it has also some disadvantages like narrow bandwidth, low gain and low efficiency. Several techniques have been evolved to improve the various characteristics of antenna; they are photonic band gap (PBG), electromagnetic band gap structures (EBG), defected ground structure (DGS). Among three methods DGS is very versatile, it is being used in various microwave devices in microwave amplifiers, microwave oscillators, microwave filter design and in microwave coupling to reduce coupling etc. now a day it is being also used in the field of antenna design as to enhance bandwidth, improve gain, size reduction, harmonic suppression, reduce cross polarization etc. The equivalent of DGS is a simple LC resonator circuit. Inductance and capacitance value of ground varies with respect to the size and location of cut. As DGS is applied to the ground inductance and capacitance value increases because of that resonating frequency gets decreases. So by varying the size and location of cut in ground we can get a desired resonating frequency. In this paper, effect of various DGS in enhancement of antenna parameter is studied

Lowpass Filter with Hilbert Curve Ring and Sierpinski Carpet DGS

Good performance and compact size are the paramaters which are vital when desiging a filter. One of the creteria of good performance is selectivity. This research, conducted by Hilbert Curve Ring and Siepinski Carpet, is used as defected ground structure to overcome filter selectivity. By using three cascadeds Hilbert Curve Ring defected ground structure cells and three steps Sierpinski carpet, a lowpass filter is designed and fabricated. The measurement result for lowpass filterwith Hilbert Curve Ring defected ground structure has sharper selectivity with the cut off frequency at 2.173 GHz and the insertion loss value is 2.135 dB. While the measurement result for three steps Sierpinski carpet has the cut off frequency at 1.728 GHz and the insertion loss value is 0.682 dB

Compact coplanar-fed tree-shaped antenna

The paper presents the concept of a fully planar tree-shaped antenna with quasi-fractal geometry. The shape of the proposed radiator is based on a multi-resonant structure. Developed planar tree has symmetrical branches with different length and is fed by a coplanar waveguide (CPW) with modified edge of the ground plane. The antenna of size 29 mm x25 mm  has been designed on  Taconic - RF-35 substrate (er = 3.5, tgde= 0.0018, h = 0.762 mm). The paper shows simulated and measured characteristics of return loss, as well as measured radiation patterns. The proposed antenna could be a good candidate for broadband applications (for instance: wideband imaging for medical application and weather monitoring radars in satellite communication etc.

Bandwidth Optimization of Microstrip Patch Antenna- A Basic Overview

An antenna is a very important device in wireless applications. It converts the electrical energy into RF signal at the transmitter and RF signal into electrical energy at the receiver side. A micro strip antenna consists of a rectangular patch on a ground plane separated by dielectric substrate. The patch in the antenna is made of a conducting material Cu (Copper) or Au (Gold) and this can be in any shape of rectangular, circular, triangular, elliptical or some other common shape. Researches of past few year shows that, various work on Microstrip Patch Antenna is attentive on designing compact sized Microstrip Antenna with efficiency and bandwidth optimized. But inherently Microstrip Patch Antenna have narrow bandwidth so to enhance bandwidth various techniques are engaged. Today’s Communication devices need several applications which require higher bandwidth; such as mobile phones these days are getting thinner and smarter but many applications supported by them require higher bandwidth, so microstrip antenna used for performing this operation should provide wider bandwidth as well as their shape should be more efficient and size should be compact so that it should occupy less space while keeping the size of device as small as possible. In this review paper, a review of different techniques used for bandwidth optimization & various shapes of compact and broadband microstrip patch antenna is given