Harmonic analysis in an islanded microgrid is a significant research topic owing to its increased installation and increased power-electronics based loads. The characteristics of frequency-dependent harmonic impedance depend on various system parameters and have a direct impact on the voltage and current distortions. In this paper, impedance measurements carried out in a laboratory microgrid operating in islanded mode are presented. These measurement results are then compared with a scaled-down low-voltage network. The paper also aims to mathematically analyze the impact of impedances between the two modes of operation. Experimental results are provided to validate the mathematical analysis on the impact of impedances on the voltage and current harmonics at the point of connection.