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Transmission characteristics of guided media

Short answer

Twisted pair: 0-1 MHz, attenuation ~3 dB/km at 1 kHz, delay 5 µs/km, repeater spacing 2 km (UTP supports Gbps up to 100 m). Coaxial cable: 0-500 MHz, attenuation 7 dB/km at 10 MHz, delay 4 µs/km, repeaters every 1-9 km. Optical fibre: 180-370 THz, attenuation 0.2-0.5 dB/km, delay 5 µs/km, repeater spacing up to 40 km.

Briefly describe about transmission characteristics (frequency range, attenuation, delay and repeater spacing) of twisted pair cable, coaxial cable and optical fiber.

The usual point-to-point transmission characteristics of the three guided media (as in Stallings) are:

MediumFrequency rangeAttenuationDelayRepeater spacing
Twisted pair (with loading)0-3.5 kHz (analog voice)0.2 dB/km at 1 kHz50 µs/km2 km
Twisted pair (multipair cable)0-1 MHz3 dB/km at 1 kHz5 µs/km2 km
Coaxial cable0-500 MHz7 dB/km at 10 MHz4 µs/km1-9 km
Optical fibre180-370 THz0.2-0.5 dB/km5 µs/km40 km
  • Twisted pair: it has a low frequency range and high attenuation, so repeaters or amplifiers are needed about every 2 km. Modern UTP supports Mbps to Gbps over 100 m.
  • Coaxial cable: the shielded construction gives a wider frequency range and lower attenuation than twisted pair, but attenuation rises quickly with frequency.
  • Optical fibre: it has the largest frequency range, the lowest attenuation and the greatest repeater spacing, so it suits long-haul links.

✓ Answer checked by Claude Sonnet 5.5

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