LMR-240 Coaxial Cable: The Industry Standard for Mid-Range RF Feeds

2026/10/15

In RF system design, there is a critical threshold where jumper cables like LMR-195 or LMR-200 become too lossy for reliable signal transmission, yet heavy-duty cables like LMR-400 are overkill for the distance and budget. LMR-240 exists precisely in this sweet spot. As the most popular mid-size low-loss coaxial cable, it serves as the definitive upgrade path from RG-8X and the go-to solution for runs between 5 and 15 meters across Wi-Fi, cellular, and amateur radio applications.

What Is LMR-240?

LMR-240 is a 50-ohm, low-loss flexible coaxial cable with an outer diameter of approximately 0.280 inches (7.1 mm). Engineered by Times Microwave Systems (now Amphenol), it features a solid bare copper-clad aluminum (BCC) center conductor, foam PE dielectric, and dual-layer foil + braid shielding. It delivers near-semi-rigid electrical performance while retaining the flexibility needed for field installation and routing through conduits.

Key Technical Advantages

1. Significant Loss Reduction vs. Legacy Cables

At 2.4 GHz, LMR-240 exhibits approximately 21% lower attenuation than LMR-200 and ~65% lower loss than RG-8X. This translates to several extra dBs of link margin—often the difference between a marginal and a rock-solid wireless connection.

2. True Outdoor & Indoor Versatility

The UV-resistant black PE jacket is rated for direct outdoor burial and aerial exposure without additional weatherproofing. Simultaneously, its smooth surface and moderate stiffness make it easy to pull through indoor conduit and cable trays, unlike stiffer LMR-400.

3. Superior Shielding Integrity

With >90 dB shielding effectiveness from its bonded foil + tinned copper braid construction, LMR-240 prevents both ingress interference and signal leakage. This is critical in dense urban deployments, data centers, and multi-operator DAS environments.

4. Broad Connector Ecosystem

As one of the most widely adopted LMR sizes, LMR-240 enjoys universal connector support. Every major RF connector manufacturer offers dedicated LMR-240 crimp and clamp connectors (N-Type, SMA, BNC, TNC, QMA, etc.), ensuring reliable terminations and consistent VSWR performance.

Quick Specifications at a Glance

Parameter	Specification
Impedance	50 Ω
Outer Diameter	0.280" (7.1 mm)
Center Conductor	Solid BCC, 0.058" (1.47 mm)
Dielectric	Foam PE
Shielding	Bonded Foil + Tinned Copper Braid (>90 dB)
Frequency Range	DC – 6 GHz (usable to 8 GHz)
Velocity of Propagation	84%
Attenuation @ 900 MHz	~6.8 dB/100 ft (22.3 dB/100 m)
Attenuation @ 2.4 GHz	~11.5 dB/100 ft (37.7 dB/100 m)
Min. Bend Radius (Repeated)	2.8" (71 mm)
Max. Operating Voltage	1,400 Vrms

Note: Always verify against your supplier’s official datasheet. Performance may vary slightly between genuine Amphenol/Times Microwave products and third-party equivalents.

Primary Applications

Wi-Fi Access Point Feeds: Standard trunk cable for enterprise APs, stadium Wi-Fi, and warehouse coverage (5–15m runs).
Cellular DAS & Small Cells: Branch and distribution lines for 4G LTE and 5G NR indoor/outdoor systems.
Amateur Radio: VHF/UHF base station antenna feeds, mobile HF whips, and repeater interconnects.
GPS/GNSS Distribution: Multi-receiver timing distribution in telecom shelters and data centers.
Industrial IoT & SCADA: Long-range sensor backhaul and machine-to-machine RF links.
Test Equipment Extension: Bench-to-DUT connections where semi-rigid is impractical.

LMR-240 Positioning in the LMR Family

Model	OD	Loss @2.4GHz	Flexibility	Typical Run Length	Role
LMR-195	0.195"	18.5 dB/100ft	★★★★★	≤3 m	Jumper / Pigtail
LMR-200	0.240"	14.5 dB/100ft	★★★★☆	3–8 m	Compact Low-Loss Feed
LMR-240	0.280"	11.5 dB/100ft	★★★☆☆	5–15 m	Standard Mid-Range Trunk
LMR-400	0.405"	6.8 dB/100ft	★★☆☆☆	15–50 m	Long-Haul Main Feeder
RG-8X	0.242"	~18 dB/100ft	★★★★☆	≤5 m	Legacy (Not Recommended for New Designs)

Critical Engineering Notes

Do Not Substitute with RG-8X: While similar in size, RG-8X uses solid PE dielectric with significantly higher loss and poorer aging characteristics. LMR-240 is a direct physical replacement with vastly superior performance.
Connector Compatibility: LMR-240 requires dedicated LMR-240 connectors. Do not attempt to use LMR-200 or RG-8X connectors—the center conductor diameter and braid capture geometry differ, leading to unreliable crimps and degraded PIM/VSWR.
PIM Considerations: For passive intermodulation-sensitive applications (e.g., multi-carrier DAS), specify Low-PIM LMR-240 variants with silver-plated conductors and optimized interfaces. Standard LMR-240 is adequate for single-carrier Wi-Fi and amateur radio.
Bend Radius Compliance: Repeated bending below 2.8" (71 mm) can deform the foam dielectric and permanently increase loss. Use right-angle adapters or pre-formed assemblies for tight corners instead of forcing sharp bends.

Conclusion

LMR-240 has earned its reputation as the workhorse of modern RF infrastructure because it eliminates guesswork. It provides predictable, documented performance across the sub-6 GHz spectrum, installs easily in both indoor and outdoor environments, and supports a mature ecosystem of compatible hardware. For any project requiring reliable mid-distance RF connectivity, LMR-240 remains the benchmark against which all alternatives are measured.

Ready to specify LMR-240 for your next project? [Browse our LMR-240 Cable Assemblies] or [Request a Custom Quote] for bulk cable, connectors, and installation tools. Our RF engineers can also help validate your link budget and cable selection.