Here is installation and the part numbers for an antenna for a E39.
The antenna cables are already pre wired in the car so, all you need is a connector box, antenna base, and the antenna radiator I chose a short radiator version, that is used on M5. The radiator is 80 mm long.
The part numbers and prices are:
84 50 8 369 458 - antenna base - $ 12.60 from Pacific BMW
84 50 8 369 459 - antenna radiator - $17.10 from Pacific BMW
84 50 8 372 699 - antenna connector box - $26.34 from Pacific BMW
Once the base and the radiator are connected together, they look like this:
This is a signal strength in dB on a screen of a Nokia phone using it's own internal antenna - "-75"
The best signal you can pull is "-50"
This is a signal strength in dB on the same Nokia mounted in the cradle and without an antenna connected - "-111" The worst signal is "-150" that you will not even see on the screen: it will jump on other tower before "-150" would show or will not lock to signal at all.
As you can see, the signal drops significantly.
To install the antenna, you need to pull the antenna cable from inside of the driver's side "C" pillar (the one sweeping from the roof to the trunk) and route the cable under the headliner to the middle point of the rear windshield. Attach the connector box to the antenna cable. Clean up the windshield using window cleaner and then clean up the same area using alcohol - pharmacies have those little alcohol pads. Once the area is clean and dry, ALIGN the connector box in the middle of the windshield, slightly below the black line at the top of the You might need to enlist help of a friend or a family member to make sure the box is aligned properly - once you remove the protective tape off the adhesive pad and stick the box onto the glass, you will not be able to move or realign the box!!!
Same goes for installing the external portion of the antenna
This is signal after installing the antenna
Several test calls in the location where the phone normally would pick up a different carrier's tower even using its own internal antenna, proved a more stable and reliable signal strength using the external antenna and would pick up a tower from its carrier. (I work for AT&T, so I can tell you, the sensitivity of the phone is much greater with this set up then without it). The next project, if it works out, will be to use the buttons on the steering wheel to voice activate the phone