Michal Pokorny

Influence of car panorama glass roofs on Car2Car communication (poster)

The Car2Car communication will use a reserved frequency band at 5.9 GHz. One of the key requirements for a Car2Car antenna is that the gain is concentrated in the horizontal plane, which is a problem due to the limited ground plane of a car roof. The influence of roof curvature, roof racks and panorama glass roofs were investigated to quantify them. To the authors knowledge such measurements have not been published yet. Three different antennas were simulated and measured on round ground planes and real car roofs in different configurations. The configuration with a panorama glass roof showed an unexpected high loss of gain in the direction of the glass roof in the range of 15 to 20 dB which result in a drastically reduced communication range to the front direction. This phenomenon is still under investigation.

Wearable Disc-Like Antenna for Body-Centric Communications at 61 GHz

In this letter, we describe the design and simulation of on-body antennas for wireless body area network (WBAN) communication operating in the 61-GHz ISM frequency band. We developed a disc-like concept of an antenna. Instead of a direct connection between a circular disc and a feeding pin, the electromagnetic coupling is used. This concept enables us to obtain relatively broadband characteristics with omnidirectional radiation pattern and vertical polarization suitable for on-body communication. Impedance properties and radiation of the antenna were studied in open space and on a tissue-equivalent phantom representing the human body. Fabricated prototype is well matched from 59.3 to 63.4 GHz. The bandwidth of the antenna is about 7%. An antenna analyzed close to body tissue exhibits efficiency of at least 25% and the maximum gain 5.2 dB in the horizontal plane.

Using Global Optimization Approaches to Reconstruct Radiation Patterns

The paper deals with the reconstruction method of the radiation pattern of directional antennas. The method is based on the amplitude near-field measurement (or simulation) on two plane surfaces, and consists of two steps. First, a global optimization is used to find an initial estimation. Second, a common Fourier iterative algorithm is created to iteratively improve the initial estimation. The genetic algorithm and the particle swarm optimization were chosen to determine the initial estimation. Their comparison was carried out on the radiation pattern reconstruction of the GSM-900 antenna.

Digitally tunable input filter unit for LTE bands

This paper deals with the design of the fast tunable filter unit which is intended to be used in combination with a reconfigurable multiband antenna. Proposed filter unit combines classical microstrip technology with digitally tunable capacitors based on the state of the art semiconductor and micromechanical technology. The design of the filter unit is described and its performance is verified by simulations. Results are compared with an equivalent lumped element band pass filter. The tuning performance of the filter-antenna combination is demonstrated.

Tunable dual-band antenna for agile communication handsets

This paper deals with the design of a compact antenna with multi-band and tuning capability for agile communication standards within LTE bands. The design of a planar dual-band antenna at cellular system frequencies is described and an innovative tuning mechanism based on EM coupling of the tunable capacitor to the resonating element is proposed. The antenna tuning ability between communication systems within frequencies from 1710 MHz to 2170 MHz band is demonstrated.

Prediction of transmission parameters of atmospheric link up to 1 THz

In the paper, the attenuation and dispersion of electromagnetic waves due to molecule resonances of gases in the atmosphere are investigated. The prediction of transmission properties exploits the generally available spectroscopic data of important gases and the measured aerological data valid for the specific geographic area. The integration technique implemented in MATLAB computational environment provides the predicted attenuation and phase dispersion characteristic for altitudes up to 35 km in frequency band 20 ÷ 1000 GHz for the arbitrary linear communication path.

Active transmission line on GaAs substrate

In order to compensate losses in metal strips, an active microstrip line on a semiconductor substrate is proposed, and its finite element model is presented. The active medium is provided by A3B5 semiconductors in external high-intensity electric field. The propagation properties of the fundamental mode are computed and the thermal analysis is performed. The problem of system stability is discussed and empirical stability criteria are introduced. A proper heat-sink is proposed to provide the operation in a continuous regime. This paper contributes to the current topic of active semiconductor waveguides and antennas which can be developed using presented concept.