This paper presents major results and comparisons of radio spectrum utilization measurements that have been carried out in three different locations in Europe, namely in the suburb of the city of Brno in the Czech Republic and in the suburb and the city of Paris in France during years 2008 and 2009 respectively. The analyzed radio bandwidth extends from 400 MHz to 3 GHz. The measurement method is based on the energy detection principle. Utilization performance and behaviors of major wireless communication systems and primary wireless system within different regions and different environments are investigated here. Our analyses pick out correlations between spectrum utilization within different regions and summarize common observations and physical aspects that will have to be considered in the future radio spectrum management to assure efficient spectrum utilization.