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The diluted magnetic semiconductors Hg(1-x)Cr(x)Se (0.03≤x≤0.1) were prepared by the solid state recrystallization method. The structure microanalysis of the Hg(1-x)Cr(x)Se compounds, performed by using a scanning electron spectrometer, has shown that the HgCr(2)Se(4) spinel-like inclusions are present in the host matrix Hg(1-x)Cr(x)Se and their amount increases when the chromium content grows. ESR studies of Hg(1-x)Cr(x)Se samples were carried out in the temperature range 4.2-300 K. ESR spectra of the samples with different chromium contents demonstrate the same g-factors at room temperature and similar fine structure development with the temperature decrease. Numerical studies of g-factors, performed by the modified crystal field approach (MCFA), allowed us to reveal that Cr(2+)/Cr(3+) ions in the tetrahedral environment of the solid solution Hg(1-x)Cr(x)Se cannot lead to the ESR signal. The experimental g-factor is well reproduced by a numerical g-factor for Cr(3+) ions located in the octahedral environment, being specific for the HgCr(2)Se(4) spinel phase. The onset of the ESR fine structure is determined by the trigonal distortions of the (CrSe(6))(9-) octahedral cell. From our study it has been found that the spinel clusters are present in the Hg(1-x)Cr(x)Se solid solution even at low chromium content.

The ultrawide‐band antenna with original transformer providing the required electromagnetic matching of the coaxial cable with the small‐size single‐arm equiangular spiral antenna is proposed. The measured input reflection coefficient of the small‐size spiral antenna is less than −10 dB within the frequency band from 7.5 to 40 GHz. The near‐fields, radiation patterns and axial ration within the impedance antenna bandwidth are presented and discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2190–2194, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27018