Hi, some of the things that can affect your signal/noise levels and the RF electromagnetic energy from the antennae:
* anything that operate in the 2.4GHz range (maybe a home phone setup? try a 5.8 GHz or 900MHz setup. Those are the federal regulations for frequencies alloted for household use)
* your microwave (assuming it's operating)
* mount it away from walls, and away from the ground... preferably on a desk, in the middle of the house
* away from anything metal
* anything dense, such as insulation/walls/furniture... the signal will be absorbed
What you can do:
* get a wireless repeater (as others mentioned)
* try changing the channels (not on the TV!
, but on the router)
* update your router firmware, the manufacturer may have included some updates since you last got it
Ah some additional information, about 10 years ago we had a house extension, when they did this they had to put two large metal girders at the adjoining sections on each floor of our house - could these cause some type of interruption to the signal?
Yes, that will affect it, too. There's a big prob right there.
another idea is to put the router in the highest part of the house, this is also recommended by many manufacturers. i have mine on my top floor and it works very well.
Not true. Read above. Who told you this?