You need to get a long HDMI lead for the pictures and sound, then use a normal aerial (CT100) cable to connect the sky IR eye in the garage. This will mean that you can control the sky box from your garage though RF2 on the back of the box and get HD through the HDMI. If you need more than 20m of cable you may need to move into fibre cables which are expensive, it may be cheaper to get extra box.
Dupe...
__________________ 105dB at 3m with 2W... without line arrays or compression drivers