@article {19_MOTL_BRANDE_ARRAY UWB, title = {UWB four elements antenna array}, journal = {Microwave and Optical Technology Letters}, volume = {61}, number = {5}, year = {2019}, pages = {1284-1294}, abstract = {Abstract In this work, a planar UWB four elements antenna array with and without notch filter is designed. The feeding system of the array is an UWB four branch multiple segment power divider/combiner. Each branch has a three segments impedance transformer. Measurements show that the array works well within the band 3.1 to 10.6 with S11 lower than -10 dB. It is shown that the maximum gain varies with the operating frequency having a value of 8 to 12.3 dB and that it is higher than the gain of the single element.}, keywords = {antenna array, notch filters, ultra-wideband antennas}, doi = {10.1002/mop.31664}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/mop.31664}, author = {B T Ahmed and J L Masa-Campos and D Brande-Hern{\'a}ndez} } @article {18_IJEC_BAZIL_MIMO, title = {(3.1{\textendash}20) GHz MIMO antennas}, journal = {AEU - International Journal of Electronics and Communications}, volume = {94}, year = {2018}, month = {september}, pages = {348-358}, abstract = {In this paper, a super-wideband (SWB) printed monopole antenna has been designed and manufactured. The measured frequency band in terms of reflection coefficient is from 3.1 to 20 GHz under a -10 dB criteria, thanks to the inclusion of a taper impedance adapter. This single antenna has been used to implement and analyze several MIMO antenna configurations, where the isolation between the compounding elements has been checked and optimized to improve the Envelope Correlation Coefficient. Two elements MIMO configurations (parallel ports or orthogonal diversity), as well as four element MIMO antennas with parallel ports are presented. Non continuous ground planes of the MIMO antenna elements with the inclusion of L shaped thin strips are proposed as valid structures to significantly improve the side by side mutual coupling from an initial peak value of 15 dB to better than 24 dB within the entire frequency band. In all the presented MIMO antenna structures, the measured values demonstrate good performance up to 20 GHz, both in reflection and isolation. Nevertheless, the influence of the mutual coupling effects has been checked as more significant in the lower part of the frequency band, especially in the 4 element MIMO configuration. The inclusion of the L shaped strips in the ground plane significantly mitigates this effect. Although the antennas have only been measured up to 20 GHz (upper frequency limit of the laboratory Vector Network Analyzer), simulations show satisfactory antennas{\textquoteright} performance up to 50 GHz.}, keywords = {MIMO antenna, Polarization diversity MIMO antenna, SWB antenna}, issn = {1434-8411}, doi = {https://doi.org/10.1016/j.aeue.2018.07.026}, url = {https://www.sciencedirect.com/science/article/pii/S1434841118310823}, author = {B T Ahmed and P Sanchez-Olivares and J L Masa-Campos and F Moreno-Vazquez} }