Publikace

The rapid development and wide commercial implementation of automotive radar sensors are strengthening the already considerable interest in matching radar target simulators. Such simulators boast promising results when used for both essential functional inspections of active sensors and the high-speed testing of numerous traffic scenarios while examining complex reactions of automobile electronic systems. For these purposes, advanced versions of target simulators enabling a generation of multiple targets moving at different velocities and ranges are required. The design, practical implementation and system programming of advanced sensor simulator setups require a detailed analytical description concerning all important technical aspects. An abundance of detailed information on the behavior and parameters of automotive radar sensors can be found in the references, but similar knowledge on sensor simulator setups is lacking. This article presents detailed analyses of the all-important RF parameters, where special attention is paid to phase noise, and its analytical description takes into account an even greater number of simulated targets. The derived analytical formulas enable both an optimal setup implementation and system programming of a wide range of practical testing procedures.

new four-port component, dual-mode impedance transformer for wideband matching of two microstrip lines with equal characteristic impedance and a coupled microstrip line with general even- and odd-mode impedances, is proposed. Practical realization problems are discussed and a new dimension correction approach is derived. Two transformers between 50-Ω microstrips and microstrip coupled lines with even/odd impedances 100 Ω /68 Ω and 36 Ω /27 Ω , respectively, were built. The concept was experimentally verified at the frequency band 0.01-16 GHz.

The paper deals with the measurement of individual components or circuits embedded in more complex radio frequency (RF) or microwave printed circuit boards (PCBs). Since no standard RF measurement enables the direct parallel connection of an analyzer to the boards being tested, individual components are often measured by destructively cutting manufactured boards and by attaching the RF connectors to the concemed parts. This article shows that this problem, thanks to suitable calibration standards that have been designed and manufactured, can be solved by vector measurements and a TRL calibration proces. The measurements also work when the boards to be measured include frequency conversion. The epplicability of the developer method has been verified by practical measurements and its accuracy influenced ot the parameters of the sumounding circuits has been investigated by an uncertaity analysis

New research and recent developments in active defense systems represent a promising way to protect military vehicles by detecting and subsequently eliminating threatening missiles with appropriate active counter-measures. Operating these defense systems requires a number of sensors, usually microwave, which must, above all, identify and track the target while generating signals to determine the correct counter-measure reaction. This paper shows that such multifunction and multimode sensors can be designed and implemented using leaky-wave antennas (LWAs). Connected radar circuits often employ a wideband modulation, so an analysis of the influence of the LWAs used on such a modulation is also included. A multimode adaptable pseudonoise radar equipped with LWAs was tested using bullets and live, armed cumulative missiles. The results confirm the functionality of the solutions presented.

This article concerns a new approach for the characterization of power-line EMI/RFI filters in a general impedance environment and continues to broaden the scope of one of previously published works. Specifically, the paper focuses on analyzing the lowest possible insertion loss of threewire, single-phase EMI/RFI power-line filters in their stop-band at high megahertz or gigahertz frequencies.

This paper deals with a general working approach for determining the lowest possible insertion loss of power-line interference filters in their stop bands at high megahertz or gigahertz frequencies. It is shown that at these frequencies, the measurement methods recommended for testing of interference filters in available standards for frequencies up to 1 GHz fail in determining their lowest possible insertion loss. This problem is solved by the newly developed method which also enables the characterization of concerned filters in a completely impedance unknown environment. It is based on two-port vector network analyzer measurement and postmeasurement data processing applying an impedance matching technique. Experimental verification of the new method using two Maury Microwave automated tuners and a cascade of low-pass coaxial filters was performed in the frequency band from 6 to 12 GHz. The results show that measurement-evaluation procedures performed according to the newly developed method provide more reliable and precise results when compared to measurement procedures corresponding to methods described in common standards. The new method was also applied to the characterization of a professional EMI/RFI filter from 1 to 10 GHz.

A new method for measuring free-space electromagnetic waves, based ona scalar interferometric measurement principle similar to the six-port concept, is presented. A proof of concept was performed at frequency band 6-12 GHz. The corresponding measurement system contains both a reference channelfeaturing a transmitting antenna directly irradiating receiving antenna, and,a test channel which has a transmitting antenna irradiating a test object. A wave reflected or scattered by the test object, and the reference wave phaseshifted in several steps, both coherent, interfere in the receiving antenna. Redundancy is exploited via a multistate regime of measurement which enablesto reduce uncertainty of measurement. A geometrical representation of theapproach in the complex plane makes it possible to estimate measurement uncertainties. Precise computing of uncertainties based on the Monte Carlo Method is alsoperformed.

This paper presents a study about the radiation problem of coaxial-to-microstrip launchers and suggests their improvement with a novel design. The proposed solution is based on a coaxial-to-microstrip transition enclosed in a parallel-plate transmission line that has its cutoff frequency above the working frequency band of interest. Any radiated field is quickly attenuated because it is propagating inside a subcritical parallel-plate transmission line. The proposed method is extensively analyzed in the CST Microwave Studio and simulation results are verified on fabricated test-fixture by multiple measurements. The proposed solution improves the accuracy and reduces the uncertainty during measurements on microstrip.

Microwave interferometry provides a sensitive measurement of amplitudes and phases of reflections. Thanks to the interferometric system can be used used to measure non-electric quantity such as distance. This letter presents a new method to evaluate data from microwave interferometer. The method is compared with the previously used procedure. The new method provides more accurate results and also offers the possibility of self-calibration.

A block of absorbing material covered by a conductive plate and placed on a microstrip line forms a structure which makes possible multimode propagation. The detailed modal analysis of the structure is presented. Based on the analysis a new planar multi-interference structure which utilizes interferences between excited modes is presented. The mentioned structure have extended bandwidth of attenuation. Experimental results and 3D electromagnetic simulations up to 18 GHz are presented.