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Docs Radio & RF Design GPS Antenna Placement

GPS Antenna Placement

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Ceramic patch orientation, distance from the radio and metal, and cold-start behavior indoors

GPS Antenna Placement

Overview

The NEO-6M module carries a small ceramic patch antenna. Its placement inside the enclosure is the difference between a 30 second fix and a beacon that never locks in the field.

Rules of Thumb

  1. Sky view is everything. The patch needs a clear hemisphere above it. Snow, a metal lid, or a conductive enclosure roof blocks it.
  2. Keep it away from the radio. The SX1262 transmits at up to +30 dBm a few centimetres away; keep the GPS patch at least 3-5 cm from the SMA connector and antenna feed.
  3. Metal under the patch helps. A ground plane below the ceramic patch improves reception. The ESP32 board’s own ground pour often provides enough.
  4. Face it up. The patch antenna is directional. Mount the module so the ceramic faces the sky, not the side of the case.

Enclosure Considerations

Enclosure materialGPS behavior
Plastic / 3D printed PLATransparent to GPS - good
Aluminium (Hammond 1593L)Blocks GPS - the module needs a window or external placement
Metal lidBlocks the signal

Note

The Hammond 1593L case is aluminium. If you mount the GPS inside it, the fix may never lock. Options: cut a window, mount the module under a plastic panel, or run the GPS on an external pigtail.

Cold Start vs Warm Start

StateTime to fixWhen
Cold start30 s to 3 minFirst boot, or after days without power
Warm start~1-15 sRecent almanac in the RTC backup or from previous boot
IndoorsOften neverGPS signals do not penetrate buildings reliably

The beacon stores the last fix in RTC RAM, so even a failed cold start still lets it transmit the previous known position.

Testing Placement

  1. Boot the beacon near a window or outdoors.
  2. Watch the serial console for [GPS ] Fix acquired and the satellite count.
  3. Move the module a few centimetres at a time and reboot to compare time-to-fix.
  4. Keep the configuration that fixes fastest in your real carrying position.