Petr Vágner

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.

Design of Microstrip Lowpass Filter Using Defected Ground Structure

A novel microstrip lowpass filter utilizing defected ground structure (DGS) units is presented in this paper. A DGS unit is simulated with different physical dimensions in order to show variation of effective inductance and capacitance. Next, a lowpass filter using proposed DGS unit is designed. A method for determining dimensions of microstrip structure and DGS units is proposed. Influence of dimensions of the microstrip structure on filter characteristics is investigated and simulated. Filters of various orders are simulated as well. Selected filter is simulated and experimentally verified.

Experimental band monitor for PSAT satellite

During changing sun activity, the ionosphere is responding accordingly and therefore it is interesting to observe the propagation behavior of shortwave bands. For the above mentioned purpose we are designing a monitoring payload for an experimental cubesat satellite called PSAT. The payload consists of a receiver, which is able to receive SSB modulated narrowband signals in 28 MHz uplink band and a transmitter with FM modulation in UHF downlink frequency band. The receiver frequency is selected to be at the center of radio amateur activity with low data rate digital modulations.

A band monitor for a cubesat-type satellite

During changing sun activity, the ionosphere is responding accordingly and therefore it is interesting to observe the propagation behavior of shortwave bands. For the above mentioned purpose we are designing a monitoring payload for an experimental cubesat satellite called PSAT. The payload consists of a receiver, which is able to receive SSB modulated narrowband signals in 28 MHz uplink band and a transmitter with FM modulation in UHF downlink frequency band. The receiver frequency is selected to be at the center of radio amateur activity with low data rate digital modulations.

Bandpass filter design using an open-loop defected ground structure resonator

This paper deals with a bandpass filter design using defected ground structure (DGS). An open-loop slot resonator is investigated and its parameters are extracted. After that, a bandpass filter is designed using coupled DGS and microstrip resonators. The combination of DGS and microstrip resonators allows use top and bottom side of the microwave substrate, therefore the resonators can partially overlap and desired coupling coefficient can be easily achieved. Finally, a sixth order BPF is designed, fabricated and measured.

High resolution easy to build 2D scanner of EM field

Paper describes the easy way to obtain high resolution EM field scanner with the use of surplus plotter and minimum mechanical modification. Examples of probes are described with its measurement results comparison. Realized software is described then and measurement examples are given. In the end there are presented suggestions for the parameters advancement.

Communication and data handling system for BRICsat satellite

The paper describes proposed satellite mission BRICsat for which all electronics parts has been designed. The modes of operation as well as data formats for telemetry and archive data are described. The results from the evaluation measurements are included in the paper.

Phase noise effects on satellite low-rate data signals

Our work focuses on investigations of phase noise effects on the low-rate telemetry transmission in satellite communication systems. In this paper, impacts of data bit rate changes on the bit error ratio are analyzed in systems, where additive thermal noise and the multiplicative phase noise are both presented simultaneously. Results indicate that as the user data bit rate rises, the character of a noise, acting within the bit period, is changing, which eventually leads to the increase of the final system BER. Results are presented via constellation diagrams and courses of BER dependencies on Eb/N0. Noise characters within one bit period are demonstrated with help of amplitude and phase distributions of detected symbols from constellation diagrams. Obtained outcomes confirm a two-state BPSK modulation resistance against the phase noise. Multi-state M-PSK modulations are much more vulnerable to the presence of the phase noise.

Effect of filtration on phase noise in communication systems

This paper deals with the investigation of a simultaneous incidence of the thermal noise and the phase noise in a BPSK/SSB communication system, while the receiver filter bandwidth is being decreased. The way of phase noise modeling is shown. A new approach of the evaluation of the behavior of both noise types is established. It gives derivations of noise powers in significant points of the communication system. The system is also modeled in Matlab and simulation results are compared with calculations, while a good agreement is achieved.

Modeling of the phase noise influence in the general M-PSK system

This paper deals with the investigation of a simultaneous incidence of an additive thermal noise and a multiplicative phase noise in narrowband low rate satellite communication systems where a multi-state phase shift keying is utilized. For the evaluation of the behavior of both noise types, a new approach is established. It derives mathematical relations of noise powers in chosen significant points of the communication system. The system model is also programmed in Matlab environment. Simulation results serve for comparisons with calculations, while a good agreement is achieved. Both noise types effects on error rates are also examined.