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Patch antenna with switchable polarization
Havelka, Michal ; Pokorný, Michal (referee) ; Raida, Zbyněk (advisor)
The bachelor’s thesis deals with the analysis of basic planar antennas, the design methods, optimization and simulation in ANSOFT Designer. Attention is turned to the design of aperture coupled microstrip antennas. First, the antenna with a simple slot is designed. Second, the design of the ring slot coupled microstrip antenna is described. Both the antennas are designed for the operation frequency 2,45 GHz. The second part is devoted to the antenna with switchable polarization. Using three PIN diodes powered by lithium battery of 3-V, the linear polarization (both the horizontal one and the vertical one) and the circular polarization (both the right-hand one and the left-hand one) can be switched. The results were verified by experimental verification.
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User influence on miniature antennas in mobile applications
Vehovský, Radek ; Polívka,, Milan (referee) ; Pokorný, Michal (advisor)
This master’s thesis deals with user influence on miniature antennas in mobile application. Electrically small antennas including fundamental performance properties and limitations are introduced in the theoretical section of this thesis. This section also deals with microstrip antennas and their common types. The accent is on PIFA antennas, their typical constructions and methods of miniaturization. In the practical section, dual-band PIFA antenna for operation at frequencies of systems GSM900 and GSM1800 is designed with the assistance of electromagnetic field simulator CST Microwave Studio. On this type of antenna, the user influence on impedance matching and radiation pattern in data mode (the user is typing message or browsing with the phone) is investigated. For this purpose the hand phantom, corresponding to author’s right hand, was made from agar based material. For typical position of human hand is designed matching network, which eliminate the user influence and ensure correct function of antenna.
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Dual-Band Helix Antenna for WiFi band
Šrajbr, Michal ; Tkadlec, Roman (referee) ; Pítra, Kamil (advisor)
This master’s thesis is focused on the properties and types of helical antennas. The helical antenna work in the different modes. These modes are described in this thesis. There are also discussed possibility for design a dual-band helical antennas. The main aim of this work is the selection of a suitable solution and design a dual-band helical antenna for the WiFi band working at resonance frequencies of 2,4 GHz and 5 GHz. The simulation of this antenna was performed in the program CST Microwave studio.
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Antenna for universal transmitter
Daněk, Jan ; Láčík, Jaroslav (referee) ; Láčík, Jaroslav (advisor)
This work describes an electrically small antennas used for mobile devices in the ISM band. The aim of this work is to select an antenna for a universal transmitter/receiver working in the 868 MHz band. The work contains description of the universal transmitter/receiver, and a list of suitable antennas. Tolerance analysis is performed by numerical model. The proposed antenna is manufactured and measured.
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Frequency doubling active antenna
Tomíček, Martin ; Černý, Petr (referee) ; Raida, Zbyněk (advisor)
This thesis deals with the analysis of a planar antenna operating at two frequencies with use frequency doubling. The design and simulation of the antenna in ANSOFT Designer is described. The antenna is designed for two operating frequencies 900 MHz and 1.8 GHz. The antenna is required to operate TM10 mode and TM01 modes.
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Planar antenna array for receiving the digital tv signal
Havelka, Michal ; Hertl, Ivo (referee) ; Raida, Zbyněk (advisor)
The master’s thesis deals in first part with the design of a single antenna element of an antenna array for receiving the digital TV. The resonant frequency of the antenna is 4.7 GHz, the antenna operates in the frequency band 4.4 to 5.0 GHz. Properties of the antenna are verified in programs CST Microwave Studio and Ansoft Designer. The final antenna element is experimentally produced. The second part is devoted to microstrip divider, 2x2 elements antenna array and 4x4 elements antenna array. The antenna array 4x4 elements was produced and its properties were measured.
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Electromagnetic field mapping in biological tissues
Bereznanin, Martin ; Dlouhý, Jiří (referee) ; Rozman, Jiří (advisor)
The main objective of this study is to learn about the theory of electromagnetic field and to create a model of propagation of ultra short waves in a biological tissue. Next point of this paper is to determine a specific absorption rate (SAR) using a valid sanitary standard. A particular model solution was realized in a model environment of the program Comsol Multiphysics 3.5. A human head and a cellular phone with an intern antenna were successfully created in this model environment. First of all were entered appropriate parameters which led to a successful representation of the distribution of electric field intensity. A value of specific absorption rate taken by a biological tissue was determined in the next step. This value was compared to the value listed in a valid sanitary standard to prevent its overrun. A development of a temperature in a biological tissue was determined as well, according to a six minutes long interval stated in a valid sanitary standard.
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Automotive antenna for mobile communications
Porč, Jan ; Láčík, Jaroslav (referee) ; Pokorný, Michal (advisor)
This thesis deals with design of flush–mounted planar disc antenna suitable for use in vehicles. For each of the bands GSM900 and GSM1800, which are used in Czech republic, an independent antenna has been created. As a simulator of the electromagnetic field the program IE3D has been used. For the improvement of theoretical results an optimisation in the program MATLAB has been developed. As the optimisation method the genetic algorithms have been selected.
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Improving antenna parameters by the application of metamaterials
Šporik, Vladimír ; Hertl, Ivo (referee) ; Raida, Zbyněk (advisor)
The thesis is focused on the design of a planar resonant-type antenna, which exploits a proper combination of left- and right-handed properties of transmission lines. This transmission line is called CRLH TL and is based on Sievenpiper mushroom structure. Advantages of the proposed antenna concept are demonstrated by a detailed comparison of its basic properties with the properties of a conventional patch antenna.
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