I have a scanner which isn't handhelp. In my room can hear Dublin Airport + airplanes no problem. Can only hear some of Westo planes. But in My attic Theres a skylight, where you can see weston... Is there a way of putting the aerial up there and runing it through a cable or something for the 20m to my room/??
If your scanner has a "BNC" connector (that's the type which requires about a quarter twist before they slide off) then you can buy a decent antenna and put it in the attic or on the roof.
You can also make them yourself quite easily. Find some RG-58 coaxial cable with a BNC connector at one end. Ask around: RG-58 coaxial cable used to be used for "thin ethernet", the main LAN standard half a dozen years ago, so computer shops or companies with a half-decent IT staff might have miles of the stuff lying about, if they didn't throw it out.
One end goes into your scanner. The other end you need to create a "dipole" antenna with. A dipole is simply a bit of metal sticking straight up, and another bit sticking straight down. Household electricity wire will do, or a clothes hangar, or something. One bit is connected to the outer mantle, the other to the inner core. I don't think it matters which is connected to which as long as you don't short circuit the core with the mantle. If you fancy fiddling, you can even pry the core wire out of the mantle at the appropriate spot and stick it up, while letting the mantle hang down.
What does matter a lot is the length of the bits of wire. For best reception, each wire needs to be a 1/4 of the wavelength of the frequency in the middle of the frequency band you want to listen to. For VHF COM, that means approximately 60 cm each.
From some experimentation I have found that the exact location of the antenna doesn't matter so much, as long as it is not surrounded by reinforced concrete. But if you have a proper dipole, tuned more or less to the frequencies you want to listen to, it makes a lot of difference compared to the tiny whip antenna that most handhelds come with. But at the end of the day, VHF signals are more or less line-of-sight so if you can see an airport from the skylight, chances are that reception in your room 20 meters away will be just as good.