Retia (Czechia)

With the increasing focus on green energy, wind turbines (WTs) have become common occurrences in most landscapes. The presence of WTs in the field of view of a radar will create very complicated clutter in a received signal. One of the major reasons for the complicated nature of WT clutter is the fact that it will consist of a wide band of Doppler frequencies. In addition, the Doppler band of frequencies keep changing based on wind speed and direction The tracking of dominant Doppler frequencies is one of the most important steps in the process of filtering WT clutter. In this work, we present an unscented Kalman filter (UKF) based solution to track the dominant Doppler frequencies in WT echoes. We have shown the efficiency of our algorithm by applying it to a wide range of real-measured data collected from various locations in Europe.

Estimating the basic characteristics of a wall is especially important in the field of through-wall radar imaging. In this article, we focus on the time delay estimation of signals measured by an ultra-wideband short-pulse radar. We describe the essential signal preprocessing steps, which are applied before a subspace super-resolution method is used to estimate the time delays of overlapping pulses backscattered from the wall. The signal correlation matrix is estimated using only one snapshot of the measured data, and the algorithm can operate in real time. In addition, to resolve closely spaced correlated echoes, we apply an improved spatial smoothing method. The performance of our algorithm is verified by simulations, and we also present the measurement results for two real brick walls. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1444–1450, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25985

Synthesized-reference-wave holographic techniques offer relatively simple and cost-effective measurement of antenna radiation characteristics and reconstruction of complex aperture fields using near-field intensity (power) pattern measurement. The near field is over-sampled. The phase is obtained indirectly, using the reference signal shifted linearly with the position of the probe. These methods allow utilization of advantages for probe compensation for near-field amplitude and phase measurements for planar and cylindrical scanning, including accuracy analyses. Descriptions are given of holographic near- field measurements using probe compensation for planar and cylindrical scanning, and numerical simulations. A comparison of holographic near-field and far-field measurements with and without probe compensation is presented.

The propagation of ultra-wideband (UWB) signals is analyzed. The UWB radar output signals are formed both with transmitter and antenna. Moreover, they can be substantially affected due to electromagnetic wave propagation through walls. Experimental results and numerical simulations are analyzed and compared. The given examples show that the numerical simulations, which are very fast, could be reliable, when suitable wall parameters are used.