Here’s a comparison of Paradar X-400 Ultra‑low‑loss Coaxial Cable (often called X-400) versus standard LMR‑400 Coaxial Cable (Per Metre) (the well-known low-loss 50 Ω coax):
📡 Purpose & Positioning
X-400
- Marketed as an “ultra-low-loss” 0.400″-diameter coaxial cable, suitable for RF work up to a few GHz.
- Often sold as a cost-effective alternative to LMR-400 and similar “.400-class” cables for short runs.
- Can be quite stiff – better for permanent outdoor installs than frequent flexing.
LMR-400
- A well-established low-loss coaxial standard (Times Microwave) used widely in RF communication, antennas, and wireless systems.
- Recognised for balanced performance, reliability, shielding, and repeatability across many environments.
🔍 Attenuation (Signal Loss)
X-400
- Often advertised with very low attenuation, e.g. < 0.193 dB per metre from DC to 3 GHz in some products.
- This implies good performance especially at 868 MHz / 915 MHz where lots of LPWAN or cellular gear operate.
LMR-400
- Typical losses (actual measured) at frequency:FrequencyApprox. Attenuation900 MHz~0.04 dB/ft (~0.13 dB/m)2 GHzhigher but still low relative to “RG” types
- Performance is validated via datasheets rather than just marketing claims.
Summary: On short runs (< 5 m), both can be similar, with X-400 often claimed to be competitive. But for longer runs LMR-400’s performance tends to be better documented in real-world use.
🛡️ Shielding & Construction
X-400
- “Ultra-low-loss” jacket and dielectric, but specifics depend on manufacturer – may vary.
- Often meant as a replacement for RG-8/LMR-400-equivalent coax, but quality varies by brand.
LMR-400
- Built with foam PE dielectric, solid conductor, and tape + braid shielding with > 90 dB effectiveness.
- This gives good immunity to interference and improves environmental durability.
📏 Practical Considerations
Stiffness & Handling
- X-400 can be very stiff, making tight bends or frequent movement harder.
- LMR-400 is still somewhat stiff but generally easier to work with and more consistent.
Installation Length
- Many suppliers recommend X-400 for short patch or extension leads, but for runs longer than ~5 m, LMR-400 is preferred due to well-characterised loss and durable construction.
Connectors
- Both can be terminated with similar RF connectors (N, SMA, BNC, PL-259, etc.), but quality of termination matters a lot for performance.
🧠 Bottom Line
Choose X-400 if you want:
- A budget alternative for short feedlines or patch cables.
- Very low loss on short runs in the 800 MHz–3 GHz bands.
- A cost-effective cable for low-power antenna extensions.
Choose LMR-400 if you want:
- A trusted, well-documented low-loss cable for longer runs.
- Better overall shielding and mechanical reliability.
- Proven performance in demanding outdoor or high-frequency systems.