Observations of polar mesosphere summer echoes (PMSE) were performed with the ALOMAR SOUSY VHF radar in the Doppler beam swinging (DBS) and the spaced antenna (SA) mode. This radar is located in polar regions at 69 o N, 16 o E in Andenes, Norway. After a summary of the basic features of PMSE and the system lay-out, we will come to the analysis of PMSE irregularity structures. Differences of the signal power observed with the DBS and the smaller SA antenna configuration point to a dominance of a scattering process of PMSE irregularities rather than to specular reflection. The SA method yields a more pronounced aspect sensitivity than the DBS method which points towards fairly anisotropic PMSE irregularities in the smaller volume sensed by the SA set-up. These anisotropic irregularity layers are frequently inclined towards the horizontal by a few degrees. There are wave and instability events which change the layer structure, their inclination and also the velocity components. When the layer inclination is not horizontal, a leakage of the horizontal velocity into the vertical velocity is manifest. It is shown that this can be corrected by using the measured zenith and azimuth angles of signal arrival and by calculating the leakage of the horizontal velocity components. This procedure yields improved estimates of the velocity components in vertical direction. Finally, some thoughts how to explain such observations of highly anisotropic and inhomogeneous PMSE irregularity structures are summarized.