Alumina-based compounds have many technological applications and attract great attention even after decades of investigation, due to their good chemical, electrical, and mechanical properties. A mixture of several alumina modifications (alpha-, kappa-, gamma-Al2O3) doped with 1 wt% of Mn2O3 was used for this experiment. The powder was mechanically activated for 60 min in an ethanol medium. After compaction, green bodies were sintered in the temperature range from 1200 to 1400 degrees C. Microstructures of the obtained specimens were investigated by scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS). The influence of morphological changes on electrical and mechanical properties was examined in detail. We have developed a test fixture and corresponding software for measurement of the relative dielectric permittivity and the loss tangent of ceramic specimens. This new method over-comes the problems of dimensions and shape of samples, as well as the problem of applying silver paste. The accuracy is around 2% for epsilon'(r) and 0.003 for tan delta. We demonstrate that the mechanical activation (MA) has the dominant influence on lowering the characteristic temperatures and microstructure development, which further leads to increased permittivity and tensile strength. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.