Comparing Coax Cables for Network Communication: Types, Specs & Selection Guide

Overview: Why Choose the Right Coax Cable

Comparing coax cables for network communication means matching electrical performance, physical durability and connector compatibility to your application. Coaxial cable remains common in CCTV, broadband hybrid systems, some last-mile links, and RF/backhaul. Key parameters include characteristic impedance (typically 50 ohm or 75 ohm), attenuation (dB per metre), velocity factor, shielding type, and connector family (BNC, F, N, SMA, TNC). This guide explains how to compare coax types, run basic calculations, and gives South Africa-relevant buying notes about availability, brands, and lead times from local distributors like Communica.

Common Coax Types and Typical Uses

• RG-58: 50 ohm, common for short RF patch leads and some legacy network links.
• RG-59: 75 ohm, widely used in CCTV, analogue video and low-frequency broadband.
• RG-6: 75 ohm, lower loss than RG-59 at higher frequencies; common for satellite and digital TV distribution.
• LMR-series (LMR-100, LMR-195, LMR-400): Low-loss cables for RF and wireless backhaul with robust shielding.
• Hardline and semi-rigid types: used for high-power or long-run RF trunks; more specialised.

Key Electrical Specs to Compare

• Characteristic impedance (Z0): mismatch causes reflections; 50 ohm vs 75 ohm decisions depend on equipment.
• Attenuation (dB/m): increases with frequency; lower is better for long runs.
• Shielding effectiveness: single, double, braid density and foil layers reduce EMI.
• Velocity factor: determines electrical length; important for timing-sensitive links.
• Power handling: relevant for RF transmitters; depends on conductor size and cable construction.

Connector Compatibility and Mechanical Considerations

Choose connectors that match both impedance and mechanical requirements. Typical connectors include BNC (75 or 50 with correct variant), F-type (75 ohm), N-type (robust 50 ohm, weatherproof), SMA/TNC (compact 50 ohm). For CCTV installs in South Africa, BNC with RG-59 or RG-6 is common; for wireless masts and professional RF, N-type with LMR-400 is typical.

A Simple Wiring/Connector ASCII for BNC (barrel-style) to F-type adapter

Coax center conductor ---- (inner pin)
Coax shield -------------(outer barrel)
Adapter body ---------- threaded F coupling

How to Read a Datasheet When Comparing Coax

• Find the nominal impedance and confirm frequency range.
• Compare attenuation at the operating frequency (e.g., 100 MHz, 1 GHz).
• Check shield coverage percentage and braid construction.
• Review temperature range and jacket material for outdoor use (UV-rated PE or XLPE jackets for exposed runs). cabrg58cu specifications and features

Selection Criteria & Calculations

To compare coax cables practically, calculate expected loss over the run and confirm connector losses do not dominate. Use the attenuation figure from the datasheet and multiply by run length.

Loss Calculation Example

Formula: Total loss (dB) = attenuation (dB/m) x length (m). Example: a 50 m run of RG-6 at 100 MHz with attenuation 0.15 dB/m yields 0.15 x 50 = 7.5 dB. If the transmitter output is 0 dBm, the receiver sees -7.5 dBm before connector and margin losses.

Return Loss and VSWR Basics

Return loss or VSWR quantifies impedance match; larger return loss (dB) is better. Mismatched impedance can reflect energy back to the transmitter and reduce effective power at the receiver. When comparing cables, prioritize those with tight impedance tolerances and consistent construction to keep VSWR low.

Troubleshooting Tips

• Intermittent video or packet loss: check connectors and crimps first, then measure attenuation with a suitable tester or replace with a known-good short run.
• High noise or interference: inspect shield integrity and increase braid density or add foil layers.
• Outdoor signal degradation: ensure UV-rated jacket and proper weatherproofing at connectors (use sealing tape or shrink boots).

Local & Procurement Considerations (South Africa)

When sourcing coax in South Africa, check local stock levels and lead times for specific LMR or low-loss branded cables; some specialised hardline types may have longer lead times. Communica stocks a wide range of coax categories and connectors; verify branch availability at Samrand for collection or request a VAT invoice for institutional/tertiary purchases. For budget planning, a basic RG-59 roll (100 m) can cost from a few hundred ZAR, while LMR-400 or N-type assemblies range higher; prices vary by brand and are subject to stock and import lead times.

Practical Examples and Recommendations

• CCTV in a small building, runs under 30 m: RG-59 or RG-6 with BNC and quality crimp connectors is usually adequate.
• Long digital video or satellite distribution: prefer RG-6 or better with 75 ohm connectors to reduce loss and preserve SNR.
• Outdoor wireless backhaul and antenna feed: use low-loss 50 ohm LMR-400 or larger with N-type connectors; minimise cable length on masts.
• Test leads and bench RF: use flexible 50 ohm RG-58 or precision SMA cables with known loss specs for lab repeatability.

Buying Checklist

• Confirm impedance matches both ends of the system (50 vs 75 ohm).
• Choose attenuation suitable for frequency and run length; calculate expected total loss.
• Pick appropriate connector type and quality crimp/soldering tools.
• For outdoor use, select UV-resistant jacket materials and weatherproofing methods.
• Check local stock, delivery estimates, and request VAT invoices for institutional orders.

Sources

• Coaxial Cable Basics and Types - RFS (Radio Frequency Systems)
• Coax Attenuation and Losses Explained - CableWholesale
• How to Choose Coax for RF Applications - Radio World
• Communica Connectors & Cable Collections
• Communica Branches & Trading Hours (Samrand, Pretoria, Cape Town)