Feedline Loss Reference
At 915 MHz, cable loss is significant. A long run of cheap coax can negate the benefit of a quality antenna upgrade.
Loss at 915 MHz per 10 meters
| Cable Type | Loss per 10m | Notes |
|---|---|---|
| RG-58 | ~4.5 dB | Avoid for any outdoor run over 2 m |
| RG-8X | ~2.5 dB | Acceptable for short indoor runs |
| LMR-200 | ~1.7 dB | Good for runs up to 10 m |
| LMR-400 | ~0.85 dB | Use for runs over 10 m |
| LMR-600 | ~0.55 dB | Very long runs; stiff and expensive |
Practical guidance
- Rooftop install with 3-5 m run: LMR-200 is ideal
- Runs over 10 m: LMR-400 minimum
- Never use RG-58 for permanent outdoor installs
- Each SMA/N connector adds ~0.1-0.2 dB loss - minimize adapters
The proximity advantage: The best way to minimize cable loss is to mount the radio enclosure close to the antenna. A 0.5 m cable run with any cable type adds negligible loss.
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