  The radiation pattern of an antenna array depends on the excitation weights
and the geometry of the array. Due to wind and atmospheric conditions, outdoor
millimeter wave antenna elements are subject to full or partial blockages from
a plethora of particles like dirt, salt, ice, and water droplets. Handheld
devices are also subject to blockages from random finger placement and/or
finger prints. These blockages cause absorption and scattering to the signal
incident on the array, and change the array geometry. This distorts the
far-field radiation pattern of the array leading to an increase in the sidelobe
level and decrease in gain. This paper studies the effects of blockages on the
far-field radiation pattern of linear arrays and proposes two array diagnosis
techniques for millimeter wave antenna arrays. The proposed techniques jointly
estimate the locations of the blocked antennas and the induced attenuation and
phase shifts. Numerical results show that the proposed techniques provide
satisfactory results in terms of fault detection with reduced number of
measurements (diagnosis time) provided that the number of blockages is small
compared to the array size.
