Tomas Korinek

Design of a Dual-Band Orthogonally Polarized L-Probe-Fed Fractal Patch Antenna Using Modal Methods

Modal methods are used to effectively design a dual-band orthogonally polarized fractal patch antenna. This letter summarizes the workflow from generating a fractal motif through modal analysis to feeding design and full-wave analysis. As the antennas feeding and matching structure, a dual L-probe was proposed to widen its bandwidth. The full-wave simulation is in very good agreement with the measurement. The motif size is 50 × 50 mm2, and the antenna operates at 1.25 and 2.1 GHz. The relative bandwidths are 4.18% and 11.4%, respectively.

Experimental verification of long-term evolution radio transmissions over dual-polarization combined fiber and free-space optics optical infrastructures.

This paper describes the experimental verification of the utilization of long-term evolution radio over fiber (RoF) and radio over free space optics (RoFSO) systems using dual-polarization signals for cloud radio access network applications determining the specific utilization limits. A number of free space optics configurations are proposed and investigated under different atmospheric turbulence regimes in order to recommend the best setup configuration. We show that the performance of the proposed link, based on the combination of RoF and RoFSO for 64 QAM at 2.6 GHz, is more affected by the turbulence based on the measured difference error vector magnitude value of 5.5%. It is further demonstrated the proposed systems can offer higher noise immunity under particular scenarios with the signal-to-noise ratio reliability limit of 5 dB in the radio frequency domain for RoF and 19.3 dB in the optical domain for a combination of RoF and RoFSO links.

Design of Stripline for EMC Testing

A comprehensive approach to the design of a stripline for EMC testing is given in this paper. The authors attention has been focused on the design items that are most crucial by the achievement of satisfactory value of the VSWR and the impedance matching at the feeding ports in the extended frequency range from 80 MHz to 1000 GHz. For this purpose, the Vivaldi-structure and other advanced structures were considered. The theoretical approach based on numerical simulations lead to conclusions which have been applied by the physical design and also evaluated by experimental results.

Short-Term Terrain Diffraction Measurements From L- to Q-Band: Results and Analysis

In response to the current need for a reliable interference and frequency coordination analysis, especially within the ground segment of satellite systems, atmospheric refraction and terrain diffraction phenomena play a key role from a radiowave propagation point of view. While it is convenient to use an ITU-R model for the case of the atmospheric refraction, several different types of models for terrain diffraction are identified in the literature. On the other hand, only a limited amount of experimental data is globally available to address their performance. This is why we carried out own short-term terrain diffraction measurements at the frequencies from L- to Q-band. During the trials, truck-mounted access platforms reaching up to 46 m above ground level were used and terrain profiles with path lengths from 7 km up to 50 km for various combinations of transmitter and receiver heights were addressed. Based on the obtained experimental dataset, the performance of the delta-Bullington and Deygout models, currently recommended by the ITU-R for the purposes of interference analysis, and the terrain diffraction models based on the UTD and parabolic equation approach has been addressed in terms of the testing variable defined in this paper.

Double ridged structures mode study for broadband antennas design

Knowledge of the cutoff frequencies of modes in nonstandard double ridged waveguides is extremely important for determination of operation bandwidth for design of broadband structures. It is shown that for nonstandard dimensions of the ridged waveguide the TE30 mode doesn¿t exist or is degenerated or the higher mode skips the TE30 mode. Strategy of the complex broadband double ridged horn antennas design (coaxial ¿ waveguide transitions, impedance transformers, radiated ridged and horn structures etc.) is mentioned and as an example the 4¿40GHz antenna is presented.

Transient response optimization of ultra wideband antennas (using particle swarm optimization)

For some ultra wideband applications (i.e. radar, positioning, etc.), it is crucial to know the transient responses of antennas. Optimization process searches for the dipole shape, which accomplishes two required parameters - namely good matching and minimal distortion. The dipoles have derivative characteristics. The distortion is evaluated from the derivative of the excitation impulse with the radiated impulse. The particle swarm optimization method was used in the process of optimization. This method was implemented in MATLABreg, where the antenna structure is generated. The antenna is subsequently simulated in the CST Microwave Studioreg. The optimized ultra wideband dipole is perfectly matched and minimally distorts the applied signal.

UHF RFID tag design for disaster management

This paper deals with the Ultra High Frequency (UHF) Radio Frequency Identification (RFID) tag design as a part of RFID localization system primarily designated for mass disasters. The design of RFID tag considers many casualties in an area of hundreds square meters, human body impedance, battery lifetime, maximal output power, resistant encapsulation etc. All requirements are taken into account in the design of several versions of RFID tag and the best one is chosen. Subsequently the design is manufactured and measured. Results show the designed RFID tag prototype is suitable for application in a disaster management.

Design of RFID outdoor localization system: RFID locator for disaster management

This paper presents an RFID outdoor localization system that is able to localize hundreds of active transponders in the area of one square kilometer using three RFID receiving stations. The RFID outdoor locator is designed for the tracking of casualties during mass disasters. Active transponders are included in triage tags that are fastened to all casualties during the first wave of rescue operations. Direction of arrival of each transponder and GPS position of three receiving stations determine the position of each active transponder in the area. The location of the transponder is displayed on a mobile terminal in maps. The paper describes a design and simulations of such system. The precision of localization of realized prototypes of the system is measured. The results and applications using the proposed RFID outdoor locator are discussed.

New antenna measurement system

A new antenna measurement system has been implemented in an antenna anechoic chamber at the Czech Technical University in Prague. The article contains the system overview, it brings the results of the first measurements and it shows the system improvements.

Influence of Input Terrain Profile Resolution on Diffraction Modeling

Tests using three selected terrain diffraction models, three available experimental datasets and three digital elevation products with different horizontal and vertical resolutions were carried out to assess the role of input terrain profile in diffraction modeling. It is demonstrated that low-resolution terrain maps are not, generally speaking, suitable for terrain diffraction modeling. Further, it is also shown that utilizing digital elevation products with medium spatial resolution results in predictions close to the case when high-resolution terrain maps are considered.