Ing. Viktor Adler, Ph.D.

This article describes a target simulator for FMCW radar sensors which, working on the frequency shift principle, deals with the presence of an unwanted (mirror) target. A simple method is proposed to suppress the mirror target by utilizing an IQ mixer in simulator circuitry which enables single-sideband modulation. Achievable combinations of speed and distance of simulated targets are also presented. In addition, the generation of targets closer than the physical distance of the simulator, a radar parameter estimation and a simulator calibration are included. All presented principles were verified by a laboratory experiment with a 24 GHz FMCW radar module and other commercially available components.

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.

This article offers insight into the design andrealization of a scalar free-space measurement system applicableto inverse synthetic aperture imaging purposes. The basics of themeasurement method are reminded and a calibration procedureof the main hardware (HW) imperfection is proposed. Themajority of the article is devoted to correctly choosing the HWcomponents, modulation scheme, assembly of the system and itscharacterisation. The functionality of the system was carried outvia the imaging of a metallic plate.

The Antenna Toolbox For MATLAB (AToM), originally an in-house academic tool, has been transformed into a complete MATLAB toolbox, capable of modeling, discretizing and calculating arbitrarily shaped planar radiators while analysing the results. All tasks can be performed directly in MATLAB. The majority of the code allows its direct modification. AToM supports the latest features, used predominantly in the realm of electrically small antennas, namely modal decompositions, evaluation of fundamental bounds, and other techniques based on the source concept.

A common approach to active antenna design consists of a passive radiator (intrinsic antenna) and an output or input amplifier; all situated on a single microwave board. Such designs show higher radiated power or lower noise floor resulting from low interconnecting line losses. However, since more microwave circuits are connected directly together on a single board, their testing is more difficult. In the given case, this concerns measurement of reflection coefficient of the passive radiator. Methods developed in frames of this work employ the VNA measurement and TRL cahbration, and enable one to evaluate radiator input reflection coefficient in a complete structure without need of any disconnecting or switching. Performed practical measurements show that results can be satisfactorily precise. Generally, the method can be applied for measurement of individual microwave circuits embedded in more complex system PCBs.

The paper proposes a method for high resolution range imaging at millimeter wave frequencies (85 GHz to 100 GHz) based on model-based compressed sensing (CS). A detailed description of the underlying CS-theory, the experimental setup and radar sensor are presented along with experimental results for one-dimensional range imaging. The proposed method is based on motorized reference measurements, which form the dictionary matrix for subsequent CS-processing. These reference measurements are tested against measurements from a glass fiber reinforced polymer (GFRP) component. A comparison of the CS-processed data to a classical Fourier-domain analysis revealed superior ranging performance of the CS-approach at the expense of a higher signal processing load.

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.

A new vector measurement method of electromagnetic field distribution in space based on a scalar measurement similar to the six-port concept is presented. In addition to transmitting and receiving, the antenna system utilizes a reference antenna continuously irradiating the receiving antennas via a coherent signal with several phase shifts. The functionality of the method was verified experimentally using three antennas in the 8 – 12 GHz frequency band. The method is applicable to imaging systems or for measuring the near field of antennas, etc.