Check out the range of DAB radio accessories available form Nevada Music; including antennas and all sorts of useful cables. Installation of an outside antenna can make a stunning difference to the performance of your digital radio set and means that you can also even receive even more stations from more distant muliplexes.
A simple dipole is the normal solution, but for areas with low receive signals, a five element or similar beam type antenna could be the answer. Cable is another important extra and is very similar to satellite TV cabling with very low loss. Most sets use the now familiar "F" type plugs which do not require soldering.
