"Thanks for the input. I understand the points made about line-of-sight, reflections and multi-pathing. But it's still not clear to me how lowering a blind or closing a door on the second floor of our house interferes with the otherwise successful reception of signal by the antenna two floors down."
Well get over it. You asked for advice and you are getting it from the best!!!
OTA, CM4221HD, 3410 amp, 4 way split, HW-150 PVR.
FTA, Openbox S9, 33” dish, PLL LNBF. Stab 90HH.