# Prototyping a GPS Pet Tracker, Board and Collar Housing, in Two Weeks pet-tech startup prepares a GPS and LTE-M collar tracker for a two-week field-trial build. Written by [Matthias Wagner](https://flux.seobdtools.com/natarius) Published Sep 2026 - 5 min read ![Prototyping a GPS Pet Tracker, Board and Collar Housing, in Two Weeks](https://flux.seobdtools.com/p/assets/blogs/gps-pet-tracker-board-collar-housing/main.webp) A pet-tech team prepares a GPS tracker for a field evaluation. The design needs an assembled board, a collar-safe enclosure, and a charging and pairing plan that fits the evaluation window. The early electronics were spread across a cellular modem module, a GPS breakout, and a battery taped to a plastic strap clip. It sent coordinates from a desk, but the battery and antenna did not fit a 25-millimeter collar. The field group wanted a rugged device that would stay attached, survive rain, and recharge without exposing a loose connector. ## Decide what the collar must report The tracker used an nRF9160 LTE-M and GNSS module, a 650 mAh lithium-polymer battery, a BQ24074 charger, and a MAX17048 fuel gauge. The device reported location at intervals selected by the handler. It used a recessed USB-C service connector during development and two gold-plated pads for charging in a dock. The RF engineer placed the module, battery connector, and antenna keep-outs on a four-layer, 42 by 28 millimeter board. The GNSS patch antenna faced the top shell, while the LTE antenna used a flexible printed element along one long edge. The RF engineer kept the battery and switching supply away from the GNSS feed and reserved a test point for charging current. The Flux agent built the schematic and board layout from the tracking and charging requirements. The RF engineer checked the module datasheet, battery protection limits, and antenna clearance. The BOM showed the chosen parts and their availability. She ran design rule checks, reviewed the charging circuit simulation, and confirmed that the SIM access would not be covered by the battery. ## Shape the case around a real collar The product manager brought a sample collar to the design review. It was 25 millimeters wide, stitched leather with a thickened seam near the buckle. A flat clip would slide toward the dog's shoulder. The mechanical engineer imported the collar buckle and strap STEP models and designed a two-piece tracker that straddled the webbing. The first housing sketch measured 44 by 32 by 15 millimeters. Its PC/ABS upper shell had a shallow recess for the GNSS antenna, while a TPU overmold protected the lower edge and kept the unit from rotating. Two stainless M2 screws joined the shell halves against a 1-millimeter silicone gasket. The collar passed through two 25.8-millimeter slots with rounded edges. In the assembly view, the battery corner pressed into the curved collar when the tracker sat beside the buckle. The mechanical engineer moved the battery 3 millimeters toward the center and changed the lower shell to follow the collar radius. The slot edges gained 1.5-millimeter radii so the strap would not fray. A side profile check showed the two antenna zones clear of the battery and the dog's neck. The product engineer asked for a charging dock that could hold the device without opening the case. The mechanical engineer added two pads on the underside and a small magnet pocket for dock alignment. The magnets sat outside the battery outline. The prototype shell used MJF PA12 with a soft TPU overmold; the production path would use injection-molded PC/ABS and a two-shot TPU grip. The gasket seam stayed accessible for assembly inspection. ## Three requests from the field-trial build > Design a collar tracker for a 25-millimeter strap. Use LTE-M and GNSS, report location at a handler-selected interval, and recharge through two protected pads in a dock. > Place the nRF9160, BQ24074, MAX17048, and 650 mAh battery connector on a 42 by 28 millimeter four-layer board. Keep the GNSS patch zone clear and route the LTE antenna along the long edge. > Fit the board and battery in the collar STEP assembly. Keep both antenna zones above the webbing, add 25.8-millimeter strap slots, and clear the 1-millimeter gasket and two M2 screws. ## Two weeks covered design and the physical prototype The product engineer, the RF engineer, and the mechanical engineer completed the electrical and mechanical review in four hours. They checked the charger, module placement, antenna keep-outs, battery envelope, collar slots, and charging pads in one project. The RF engineer approved the cell interface and the mechanical engineer signed off on the shell dimensions. The Flux agent carried the board changes into the case assembly and kept the BOM current. The prototype package included a four-layer board with the nRF9160, BQ24074, MAX17048, SIM interface, battery connector, LTE antenna, and GNSS antenna zone. Its housing files showed the PC/ABS shell, TPU overmold, M2 fasteners, gasket, collar slots, and charging pads. the startup ordered assembled boards and MJF shells for the twelve-unit trial. During the two-week schedule, board fabrication and assembly ran alongside the printed case work. The team checked each assembled board at the bench, paired it with a phone, and confirmed a location report before installing it on a collar. The team also inspected the gasket seam and dock contact pressure. That timetable included fabrication and first-article checks; Flux design work took hours, not the full the project window. The field group received trackers that clipped around its actual collars rather than a generic strap mock-up. The product engineer recorded the unit serial, battery level, and pairing status for each device. The mechanical engineer kept the collar slot dimensions in the mechanical drawing so a later size change would have a clear starting point. Before the handoff, the product engineer placed each tracker on the collar sample, checked that the buckle could still move, and recorded the GPS fix beside the battery reading. ## A pet-tracker prototype checklist - Set the collar width, buckle size, and attachment position from real strap samples. - Confirm LTE-M and GNSS module requirements, antenna zones, and battery protection. - Keep the cell away from RF antennas and the charging circuit's hot parts. - Check strap-slot radii, gasket compression, fastener access, and dock contact alignment. - Build and test assembled boards before loading them into printed shells. - Reserve time for charging, pairing, location checks, and first-article inspection. [Start your project at flux.ai](https://flux.seobdtools.com/) ## About the author [Matthias Wagner](https://flux.seobdtools.com/natarius) Founder & CEO at Flux Matthias is the Founder and CEO of Flux, a hardware design platform that's revolutionizing how teams create and iterate on circuits. Find him on Flux [@natarius](https://flux.seobdtools.com/natarius). Let’s start building Build your big idea together with Flux. All you need to do is describe what you want to make, or what problem you want to solve. Flux will work with you to make it a reality. ![Close-up photo of a PCB made with Flux, with an ESP32 module, buttons, and a microSD slot.](https://flux.seobdtools.com/p/assets/blogs/miscellaneous/sidebar-cta-pcb.webp) [Try it Free](https://flux.seobdtools.com/signup) ## Related Content [ ![Line illustration of an old audio amplifier product in an exploded view](https://flux.seobdtools.com/p/assets/blogs/design-software-license-lapsed-product-line/main.webp) ### Your Design Software License Lapsed. 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