The optimal simulated structure was approached in the experiments. Deposition from concentrated 140 nm NPs suspension enabled of 11 % surface coverage. For this sample the measured reflection was about 25 % in the vissible range while simulation predicted antireflection like effect with even 0 % reflection for 490 nm. This dispcreapncy was the driving force for the actual microstructural features investigation. Surprisingly, the diffused component of total reflection showing position of plasmonic peaks corelated well with simulated predictions. The investigated ascepct covered: influence of NPs size distributions, random arrangement and presence of agglomerates. Cumulated results indicated really increded reflection and hence partially explained observed discrepancy.