I tried one of those IR senders to transmit from a sky box upstairs to downstairs. Complete waste of time.
The first one, from Comet (24 Ghz I think) didnt get any sound through and just a fuzzy picture. Took that back and got a better one from Maplins (56Ghz?) for about £70. Worked OK in perfect weather and if no-one moved in the house, otherwise flaky picture and lots of sizzle on the sound.
Given up with them completely now and cabled right round the outside of teh house (which I was trying to avoid) but got great picture now!
Maplin box for sale if anyone is interested – just don’t expect it to get signal through 1 timber floor and 1 masonry internal wall.