# Field Antenna Testing Without Lab Equipment

Professional antenna testing requires a vector network analyzer and anechoic chamber. Field testing with simple tools can still tell you whether an antenna is working as expected for your deployment.

## The Two-Node RSSI Test

The most practical field test for comparing antennas:

1. Set up a reference node at a fixed location (indoors at a window, or on a tripod outdoors)
2. Connect your test antenna to the mobile node
3. Walk to a consistent test point 50-200m away
4. Record RSSI (in dBm) displayed in the [Meshtastic app](https://wiki.meshamerica.com/books/hardware-guide/page/meshtastic-app) on either node
5. Replace antenna with a known reference (stock rubber duck or a calibrated dipole)
6. Return to the same test point and record RSSI again

RSSI difference in dB = antenna gain difference (approximately). A +3 dB improvement means the new antenna has ~3 dB more gain than the reference.

**Important:** Test at multiple azimuths (compass directions) for [directional antennas](https://wiki.meshamerica.com/books/antennas-rf/page/directional-antennas). Omnidirectional antennas should show similar RSSI regardless of direction.

## Checking for Antenna Resonance with an SDR

An RTL-SDR dongle ($25) can help verify antenna resonance:

1. Connect the test antenna to the SDR via an appropriate adapter
2. Open SDR# or GQRX
3. Look at the noise floor across 900-930 MHz while the antenna is connected vs. with a dummy load or no antenna
4. An antenna that's resonant near 915 MHz will show elevated noise pickup compared to a non-resonant antenna at that frequency

This isn't a precision measurement, but it can confirm whether an antenna is "alive" at the target frequency.

## Common Field Issues and Quick Diagnosis

<table id="bkmrk-symptomlikely-causeq"><thead><tr><th>Symptom</th><th>Likely Cause</th><th>Quick Test</th></tr></thead><tbody><tr><td>RSSI much worse than expected</td><td>Wrong frequency antenna, damaged element, or loose connector</td><td>Swap with known-good antenna; check connector seating</td></tr><tr><td>Range varies wildly with orientation</td><td>Antenna is directional (yagi, patch), or near-field coupling to enclosure</td><td>Mount antenna away from metal surfaces</td></tr><tr><td>Range degrades after outdoor installation</td><td>Water ingress into connector or pigtail</td><td>Inspect connector for corrosion; re-weatherproof</td></tr><tr><td>Node transmits but no one hears it</td><td>Open circuit in antenna path (broken cable, wrong adapter)</td><td>Check SWR at transmitter; swap cable</td></tr></tbody></table>

## Documentation for Installations

For permanent outdoor installations, document your baseline measurements:

- Date of installation
- Antenna model and supplier
- SWR at 915 MHz (from NanoVNA if available)
- RSSI to 2-3 reference nodes at known distances
- Photos of antenna mounting and connector weatherproofing

This documentation makes troubleshooting future performance issues much faster - you have a baseline to compare against.