  We discuss the design and expected performance of STRIP (STRatospheric
Italian Polarimeter), an array of coherent receivers designed to fly on board
the LSPE (Large Scale Polarization Explorer) balloon experiment. The STRIP
focal plane array comprises 49 elements in Q band and 7 elements in W-band
using cryogenic HEMT low noise amplifiers and high performance waveguide
components. In operation, the array will be cooled to 20 K and placed in the
focal plane of a $\sim 0.6$ meter telescope providing an angular resolution of
$\sim1.5$ degrees. The LSPE experiment aims at large scale, high sensitivity
measurements of CMB polarization, with multi-frequency deep measurements to
optimize component separation. The STRIP Q-band channel is crucial to
accurately measure and remove the synchrotron polarized component, while the
W-band channel, together with a bolometric channel at the same frequency,
provides a crucial cross-check for systematic effects.
