Q: Why does an RRH raise a VSWR alarm on one antenna port and then lose one frequency after 1–2 hours?
When this happens, the first thing to check is the RF path connected to the affected port, not the band configuration itself.
In the current case, the logs show the VSWR alarm only on Ant1. That points to one specific RF branch rather than a generic software issue affecting both carriers equally.
A VSWR alarm means the radio detects excessive reflected power on the RF path. In practical terms, the transmitter is not seeing a proper 50-ohm load. When that mismatch becomes too large, the PA protection may reduce or stop transmission on that path. Depending on carrier mapping, this can appear as the loss of one frequency.
Most likely causes
- A problem on the external RF chain connected to the affected port.
- An attenuator, load, antenna, cable, or adapter that is defective or not properly matched in frequency or power.
- Poor ventilation or heat buildup that makes an already marginal RF condition worse over time.
- If the fault remains on the same radio port after swapping the external RF chain, a hardware issue on one RF path inside the radio.
Recommended checks
- Swap the RF chains between ports to see whether the alarm follows the radio port or the external chain.
- Temporarily replace the antenna with a proper 50-ohm load and repeat a long-duration test.
- Check that the attenuator, loads, antenna, and RF accessories are compatible with the actual frequency range and transmit power used.
- Check all RF cables and adapters for damage, loose connection, or poor contact.
- Verify that the radio has adequate ventilation and is not operating in a poorly circulated environment.
How to inspect the logs
To review the logs directly, connect the EdgePOD to the internet, then open the edgepod-enb service from the instance tree. From there, use the monitor-setup-url to access the monitor application and review the private logs. The VSWR alarm promise details can also help identify which antenna path is affected.
For more details, see: