The antenna is Trimble part number 28367-00. Pac Comm can be reached by phone at 800.486.7388. They are preparing to market a model in the US, that has been selling in Europe. Jano also has an active antenna, boasting a 30 dB gain figure, and is a magnetic mount. This comes with a 10 meter lead, terminated with a male micro-connector that connects to the female MCX connector.
Shipping is from Ontario, Canada.
I've tested both the passive and active antennas from Jano, and found them both to be very good performers, especially with satellites that are closer to the horizon. The power draw on the active unit is slightly more than the Lowe antenna, but the gain seems to be better as well. More information and pictures are available on the antennas page . Ham Radio Outlet is carrying the Garmin 35, which is basically the same as a Garmin 45, but with a built-in antenna, rather than the removable antenna on the 45. The 35 does have a serial port built in, so it can be used for APRS, but you lose the ability to connect to an external antenna.