Hey everyone,

Wanted to share some useful info that came up recently around Geotab GO device installations — specifically around antenna orientation and how it affects GPS performance. This information doesn't seem to be commonly known and is CRITICAL for anyone that deals with GO Device Hardware.

The Antenna Is Directional and is located on the UNDERSIDE/BOTTOM of the device!

Contrary to what you might assume, the internal GPS antenna in Geotab GO devices is directional — not omnidirectional like your phone's antenna. It's physically located on the underside of the device, beneath the printed label/logo.

When the device is plugged directly into the OBD-II port under the steering column, the antenna faces downward toward the floor. However, this still works because GPS signals bounce off the asphalt and the vehicle's metallic chassis floor, acting as a reflector. So, although it may not be ideal, it is functional by design for standard plug-in installs. Remember, the designing engineers have to create a product that is as forgiving as possible- the end result is a compromise and results in hardware that is functional in the broadest array of installations/applications.

Hidden/Harness Installs? Flip It Upward

If you're using a T-harness or extension cable to tuck the device inside the dash, the rules change. Geotab's own GO9 support guidelines say you should orient the device with the label/antenna side facing up toward the sky whenever possible.

Direct line-of-sight to the satellites overhead gives you:

• Faster GPS latch times on startup
• Lower Position Dilution of Precision (PDOP)
• More accurate, consistent tracking data

Getting this wrong (antenna pressed against metal, or facing the wrong way in a hidden install) can result in "straight-lining" on your fleet maps — where the system can't get a valid lock and just draws a straight line between the last two known good coordinates.

How Glass Affects the Signal

The impacts of vehicle glass is often forgotten or overlooked, but nonetheless critical to performance and stability. Here's a quick breakdown:

Glass Type / GPS Impact

Standard clear glass / ✅ No impact — GPS passes right through

Non-metallic aftermarket tint (dyed/carbon) / ✅ No impact — signal-safe

Metallic/hybrid tint / ❌ Significant degradation — metal particles create a Faraday shielding effect

Ceramic tint / ✅ No impact — heat-rejecting but signal-friendly

Factory solar/athermic windshields / ❌ Significant degradation — thin metal oxide layer blocks signal

If your vehicles have factory "acoustic" or solar-reflective glass (very common in newer model years), be aware that tucking the device under the dash and relying on windshield pass-through may cause issues.

Pro tip: Look for the dot matrix zone — the black speckled band typically found near the rearview mirror mount. Manufacturers intentionally leave this area free of metal oxide so that devices like toll passes and telematics units can receive signals through the glass. This is often the best spot to aim for signal penetration.

Hope this helps someone avoid a head-scratcher during their next install!

Thanks!!!

(Mods: feel free to move if there is a better place for this info to reside)