LTE-M OBDII dongle 

The GPSauge OBD device already uses internal GNSS and GSM antennas on a compact platform designed for vehicle‑mounted installation. The main challenge was to add coverage in lower‑frequency cellular bands 8 and 20 (typical for NB‑IoT‑style use) with a compact, license‑free PCB antenna, while keeping Band 3 (LTE uplink / 2G‑like) usable without redesigning the housing or PCB.

As a solution, we implemented a FreeTrack PCB antenna tuned primarily for Bands 8 and 20 (around 790–960 MHz). The FreeTrack trace leverages the existing device groundplane and is routed so that it stays robust against nearby metal structures such as the OBD plug and harness. This yields high efficiency with minimal extra board area, similar to compact NB‑IoT PCB antennas in this band range.

For Band 3, we added a FreeLoop chip loop antenna and combined it with the FreeTrack antenna via a diplexer. The diplexer cleanly separates Band 8/20 and Band 3 and routes both signals over a single RF path to the modem. This avoids two separate antenna ports, keeps board complexity low, and keeps coupling between bands below the interference threshold.

At the same time, we implemented a FreeLoop GNSS PCB antenna that receives both L1, L2 and L5 signals from GPS, Galileo, BeiDou and GLONASS. The FreeLoop structure runs on the tight OBD PCB, keeping safe distances from CAN lines and power nets, while the short loop‑section (FreeLoop‑like trace) helps stabilize the L1, L2 and L5 resonance. As a result, the device achieves high GNSS sensitivity and reliability even under poor‑sky conditions inside vehicles.

Benefits for the customer

• Two cellular antennas, one RF line: Combining FreeTrack (Band 8/20) and FreeLoop (Band 3) via a diplexer reduces board real estate and simplifies integration into the existing OBD design.

• Compact GNSS solution: The FreeLoop GNSS antenna covers L1, L2 and L5 simultaneously and uses the short loop trace for clean tuning, without extra components.

• License‑free and low‑maintenance antennas: All antennas are passive and do not require licensing, which lowers long‑term operating costs for the telematics service.

• Robust in vehicle environments: The antennas are explicitly tuned for the metal‑rich, cable‑dense environment around an OBD port (chassis metal, nearby connectors, short ground routing), so efficiency and GNSS positioning stay stable even in challenging installations.