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Fiber Optic vs Coaxial Cable: Key Differences, Uses & Which to Choose
When planning a satellite, VSAT, or telecom installation, one of the first decisions you face is cable type. Fiber optic and coaxial cable both carry signals from point A to point B — but they work in completely different ways, and choosing the wrong one means poor performance, expensive rework, or a system that won’t scale.
This guide breaks down everything you need to know: how each cable works, where each excels, and how to make the right call for your specific project.
What Is Coaxial Cable?
Coaxial cable carries RF signals as electrical waves along a center copper conductor, insulated from a surrounding braid or foil shield by a dielectric foam core. The shield keeps the signal contained and reduces external interference. An outer PE or PVC jacket provides mechanical and weather protection.
In VSAT and satellite applications the most common types are LMR-400 (standard Ku-band IFL, runs to ~30m), LMR-600 (medium runs to ~60m), LMR-900 (long runs to 80m+), and legacy RG-214. For broadcast and CATV distribution, 75Ω RG-6 is standard.
The capability that makes coaxial indispensable for satellite work: it carries DC power alongside the RF signal. The same cable that carries your IF signal from modem to LNB also delivers the 13V or 18V DC that powers the LNB — plus the 22 kHz polarisation tone — and the 24–48V DC that drives the BUC. No other single cable can do this.
What Is Fiber Optic Cable?
Fiber optic cable carries signals as pulses of light through a glass core, surrounded by cladding (a lower-refractive-index glass layer that traps light inside by total internal reflection), a protective buffer coating, and an outer jacket. There are no copper conductors — signals travel at the speed of light with virtually no attenuation over distance.
Two main types exist: single-mode fiber (SMF, OS1/OS2) for long-distance runs up to 40+ km, and multi-mode fiber (MMF, OM3/OM4) for shorter data links up to ~300–550m. For telecom backhaul and building-to-building links, SMF OS2 is the current standard.
The defining advantages: attenuation of just 0.2 dB/km at 1550 nm (versus approximately 6.6 dB/100m for LMR-400 at 1 GHz), complete immunity to electromagnetic interference, and effectively unlimited bandwidth. The defining limitation: fiber cannot carry DC power. Any powered equipment at the far end requires a separate power cable.
Signal Attenuation: The Numbers That Decide Everything
Signal loss — attenuation — is the single most important factor in cable selection. Here’s how the main cable types compare at 100 meters:
At Ku-band frequencies (12 GHz), coaxial losses are significantly higher still — LMR-400 loses approximately 30 dB per 100m at Ku-band, which is why VSAT IFL runs must be kept short or upgraded to larger cable (LMR-600 or LMR-900).
Fiber Optic vs Coaxial: Full Comparison
| Feature | Coaxial Cable (LMR-400) | Fiber Optic (SMF OS2) |
|---|---|---|
| Signal medium | Electrical (RF waves) | Light (photons) |
| Attenuation @ 1 GHz | 6.6 dB / 100m | 0.02 dB / 100m |
| Attenuation @ Ku-band (12 GHz) | ~30 dB / 100m | N/A — not RF |
| Max VSAT IFL run (Ku-band) | 30m (LMR-400) · 60m (LMR-600) · 80m+ (LMR-900) | Not suitable for IFL |
| Max data run (1 Gbps) | ~100m (Cat6 Ethernet) | 10+ km (SMF) |
| EMI immunity | Partial — braid reduces, does not eliminate | Complete — light is unaffected by EMI |
| DC power over cable | ✓ Yes — LNB 13/18V + BUC 24–48V | ✗ No — separate power cable required |
| RF signal (native) | ✓ Yes | ✗ No — requires optical conversion |
| Bandwidth | DC to 40 GHz (LMR-600) | Practically unlimited (>100 THz) |
| Field termination | Easy — crimp tool + N-type / SMA / BNC | Requires fusion splicer + cleaver |
| Security | Can be passively tapped | Tap causes detectable signal loss |
| Ground loop / surge risk | Yes — copper conductor | None — glass is non-conductive |
| Weight | Heavier | Very light |
| Cable cost | Lower | Moderate to high |
| Equipment cost | Lower | Higher (transceivers, media converters) |
| Typical connectors | N-type, F, BNC, SMA, TNC | LC, SC, ST, FC |
When to Use Coaxial Cable
✓ Coaxial is the right choice for:
VSAT and satellite IFL runs — Mandatory. Your satellite modem must deliver DC power to the LNB (13V/18V + 22 kHz polarisation tone) and BUC (24–48V) through the same cable that carries the IF signal. Use LMR-400 up to 30m, LMR-600 to 60m, LMR-900 to 80m+ at Ku-band.
Antenna feedlines — VHF/UHF, cellular base station, and microwave antenna connections are always coaxial. LMR-400 is the standard for fixed base station feedlines; LMR-600 for tower runs over 20m.
RF signal distribution — Splitters, combiners, amplifiers, RF patch panels: anywhere you’re routing a live RF signal, coaxial connections are required throughout the chain.
CCTV and analog video — Analog camera systems (HD-CVI, TVI, AHD) use RG-59 or RG-6. Still widely deployed throughout the GCC due to existing cable infrastructure.
Remote DC power delivery — Any equipment that needs power over the cable (BUC on a tower, LNB on a dish) requires coaxial IFL. There is no alternative.
Field installations — Coax connectors are field-terminable with a hex crimp tool. Fiber fusion splicing requires capital equipment and a clean environment — coax wins on field flexibility every time.
When to Use Fiber Optic Cable
✓ Fiber optic is the right choice for:
Long data backbone runs (>100m) — Any network link over 100 meters at Gigabit speeds or higher should be fiber. SMF supports 10G Ethernet over 10+ km without amplifiers.
Building-to-building links — Outdoor aerial or buried runs between buildings need fiber for ground-loop isolation and lightning surge protection. Copper cable between separate structures can conduct a surge that destroys equipment at both ends.
High-EMI environments — Generator rooms, industrial motor drives, high-voltage transformer enclosures: fiber is completely immune to electromagnetic interference regardless of the surrounding electrical noise.
High-bandwidth data (40G / 100G / 400G) — These speeds require fiber. Not achievable over coaxial cable at any practical distance.
Security-critical links — Fiber cannot be intercepted passively. Any physical tap causes a measurable signal loss that optical monitoring can detect and alert on.
Harsh or marine environments — Fiber is immune to salt air corrosion, moisture ingress effects on signal quality, and temperature-driven impedance changes.
Why VSAT Always Uses Coaxial — Without Exception
In any VSAT installation — from a single maritime terminal to a large teleport earth station — the IFL between the satellite modem and the outdoor unit must be coaxial cable. The reason is simple: the modem or ODU controller delivers DC power to the LNB and BUC through the same coaxial IFL that carries the IF signal. Fiber optic cable cannot carry DC power.
Fiber-based IF extension systems do exist. They use optical modulators and demodulators with separate power injectors to extend IFL runs beyond 100 meters in large earth station facilities. But these are expensive, complex installations reserved for sites where very long cable runs make standard coax impractical. For any typical VSAT site, coaxial cable is the correct and only practical IFL solution.
Frequently Asked Questions
BravoSatcom stocks LMR-400, LMR-600, LMR-900 and IFL cables. We ship across the GCC.
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