A New Concept of PTP Vector Network Analyzer

A new concept for vector network analyzers design based on a perturbation two-port (PTP) is presented. The approach uses redundant states of the PTP. The best states of the PTP for a certain place in Smith chart and frequency are chosen to determine a reflection coefficient with minimum uncertainty. Four criteria for the selection are designed. The criteria were tested on measured parameters of different states of the PTP. Significant improvements in PTP bandwidth and uncertainty of measured data were achieved

Tropospheric Propagation above Uneven Ground

Analyzujeme šíření nad nerovnou zemí s uvážením vlivu troposféry pomocí fyzikální optiky. Prezentujeme nové výsledky numerických simulací pomocí fyzikální optiky pro pracoviště měření antén ve vzdálené zóně, studie změn indexu lomu a diagramy krytí radarů. Výsledky jsou ověřovány jak experimentálně, tak i jinými numerickými metodami.This work analyzes the electromagnetic wave propagation above uneven ground, including the troposphere, using physical optics calculation. The new results of numerical simulations using physical optics are presented

Pracoviště pro měření antén

Measurements of test antennas are performed on antenna ranges. The operated microwave far-field outdoor range was built-up in 1970’s and therefore it was not appropriate for the today measurements. Thus, it was decided to perform the complete reconstruction and testing. Some results of new ample measurement campaign are just given. The optimization of antenna range using merely measurement is very inefficient, and therefore that is done by numerical simulations. Consequently the paper surveys briefly electromagnetic wave propagation over irregular terrain. The physical optics approximation of vector problem was chosen. That allows the comparison of selected numerical simulations and measurements for the reconstructed far-field range. A possibility of antenna range optimizing by using numerical simulation considering various constraints is verified.Měření se provádí na speciálním pracovišti. Pracoviště bylo vybudováno v sedmdesátých letech a proto se provedla kompletní rekonstrukce. Optimalizace se prováděla numericky

Radars in transportation

The key concept of radar is relatively simple but its practical implementation could be very complicated. An active radar radiates electromagnetic energy and detects the echo returned from reflecting objects (targets). The nature of the echo signal provides information about the target. The distance to the target determines the time of the radiated energy to travel to the target and back. The angular location defines a directive antenna. A radar can derive the target trajectory, and predict future location. With sufficiently high resolution, the radar can distinguish something about a target's size and shape. Usually, the radar is an active device in that it carries its own transmitter and does not depend on ambient radiation, as do most optical and infrared sensors. The radar can detect relatively small targets at near or far distances and can measure their range with precision in all weather. On the other side, the passive surveillance technology provides an unmatched ability to "see without being seen" and provides the very advanced technology. The described properties are very useful for transportation. The students of University of Pardubice and their teachers have cooperated on the development of various kinds of radars produced in the Czech Republic. Several examples such as air traffic control, river and automotive radars, which are used in transportation, are briefly illustrated

Optimalizace pracovičtě pro měření antén

Measurements of test antennas are performed on antenna ranges. The operated microwave far-field outdoor range was built-up in 1970’s and therefore it was not appropriate for the today measurements. Thus, it was decided to perform the complete reconstruction and testing. Some results of new ample measurement campaign are just given. The optimization of antenna range using merely measurement is very inefficient, and therefore that is done by numerical simulations. Consequently the paper surveys briefly electromagnetic wave propagation over irregular terrain. The physical optics approximation of vector problem was chosen. That allows the comparison of selected numerical simulations and measurements for the reconstructed far-field range. A possibility of antenna range optimizing by using numerical simulation considering various constrains is verified.Měření antén se provádělo na pracovišti ze sedmdesátých let a proto se rozhodlo o kompletní rekonstrukci. Optimalizace se prováděla pomocí fyzikální optiky numerickou simulací a různá omezení se verifikovala experimentálně