This thesis deals with RFID tags design. It comprises an overview of the RDIF technology while focusing upon the passive tags in UHF band. The CST Microwave studio software has been used for draft simulations. The resulting tags have been subjected to parameter measuring – the reflection coefficient, the minimum capacity needed to switch on the tag, the maximum reading distance. The influence of the proximity of metal objects and other materials has also been examined.

The diploma project deals with the numerical modeling, implementation and measurement of dielectric dipoles excited by a coaxial probe. Attention was turned to shape optimization of dipoles from the viewpoint of ultra wideband parameters in the band group 6. (“Bandgroup 6“). Two antennas exhibiting the best parameters were fabricated. Results of measurements were compared with simulation results. Simulations and measurements were in agreement. For the simulations, we use program CST Microwave Studio.

Dielectric High-frequency transmission lines are natural alternative to the lines made of metal in term of low loss. These lines are mainly used in microwave techniques of measuring. The main object is to describe basic parameters of metal and dielectric transmission lines and their comparison. Next point is a basic overview of the excitation the lines from metal and it's application on dielectric transmission lines. Then make the simulation of microstrip directional couplers and coupler made by dielectric waveguides. The last point of work is construction these directional couplers and measuring their most important parameters.

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.

This master’s thesis describes the theoretical analysis of the Sierpinski triangle structure. On the basis of this structure, a planar version of the Sierpinski monopole is firstly designed. Then, by using a transfer of the planar motive to the conical surface, conical and cascade Sierpinski monopoles are designed. All simulations are calculated by CST Microwave Studio 2011. In the thesis, four types of cascade Sierpinski monopole are proposed. The investigated parameters are reflection coefficient, input impedance, radiation properties, polarization and bandwidth. The attention is primarily focused on the design and experimental verification of the selected conical shape cascade Sierpinski monopole set on the bands GSM 900, GSM 1800 and Wi-fi 2,4 GHz.

The aim of this diploma thesis is to study the possibilities and problems of low-profile antennas and subsequently to design a directional antenna with spherical reflector for millimeter wavelengths. The theoretical part deals with basic information about horn and reflector antennas, and about SIW technology. In addition, the thesis deals with the specific design and modeling of the antenna using CST Microwave Studio. The simulated design achieved a sufficient bandwidth to cover ISM (57 GHz to 64 GHz) with gain 13.6 dBi at 60 GHz frequency. On fabricated antenna, the antenna impedance ratios were worse and the target bandwidth was not reached. Antenna gain was 14.33 dBi at 60 GHz frequency.

In this thesis is discussed a filter design of a band-pass substrate integrated waveguide filter on the frequency of 5 GHz. It also includes design theory, filter synthesis, filter analysis in the program CST Microwave Studio® and the results of measurement on a vector network analyzer. The analysis results are compared with the measured results. Good agreement between simulated and measured results is observed.

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.

This work focuses on the design circularly polarized serial antennas array operate in the ISM band (5.725 GHz to 5.875 GHz). Design of antennas is divided into three parts. In the first part is designed feeding system, followed by two types of circularly polarized antennas and at the last point, these components are integrated. Furthermore, these antennas are fabricated, measured their parameters and used for experimental verification of the influence of multipath transmission in-vehicle.

<p>Nonlinear transmission lines (NLTLs) are of great interest for high power microwave (HPM) generation because they can sharpen pulses to create an electromagnetic shockwave to produce oscillations from 100 MHz to low GHz. NLTLs provide frequency agility, compactness, durability and reliability, providing a solid-state radiofrequency (RF) source for producing HPM. The essential component of NLTLs is the nonlinear material, typically a dielectric that varies with voltage or a magnetic material whose permeability varies with current, incorporated in the transmission line in various topologies. This thesis presents an alternative approach involving designing composites comprised of nonlinear dielectric inclusions (barium strontium titanate (BST)) and/or nonlinear inductive inclusions (nickel zinc ferrites (NZF)) in a polymer base host material, analogous to electromagnetic interference designs that incorporate stainless steel inclusions of various shapes in a plastic to tune the composite’s electromagnetic properties at GHz. Appropriately designing NLTL composites requires predicting these effective properties both in linear (for a fixed and low voltage and current) and nonlinear regions (permittivity and permeability become voltage dependent and current dependent, respectively) prior to designing HPM systems comprised of them. As a first step, this thesis evaluates and benchmarks composites models in the commercial software CST Microwave Studios (CST MWS) to various effective medium theories (EMTs) to predict the permittivity and permeability of composites of BST and/or NZF inclusions in the linear regime, compared with experimental measurements. The manufacturing and measurement of the nonlinear composites will be briefly discussed with an analysis of the homogeneity of a composite sample using 3D X-ray scan. Long-term application of these approaches to predicting the effective nonlinear composite permittivity and permeability and future work will be discussed.</p>