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I need to buy some coax cable for TV via satellite. I see they are marked in dB: 135, 130, 120 down to 95. Then there are multiple layers (up to 5) and shielding copper (cu) vs aluminum (alu.)

Is my understanding correct that the higher the dB number the better the cable? Is cu shield better than alu?

I assume for the core cable as well, copper is better than alu.

I need to put it in the wall, and just want the best (i.e. most future proof cable), with minimum potential interference (5G, LTE, etc.)

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  • \$\begingroup\$ What application? RF? CableTV? 50 Ohm? 75 Ohm? \$\endgroup\$
    – Lior Bilia
    Commented May 24, 2022 at 14:14
  • \$\begingroup\$ @LiorBilia good point, Satellite TV (updated the question) \$\endgroup\$
    – Roger
    Commented May 24, 2022 at 14:17
  • \$\begingroup\$ Link to an example, please. \$\endgroup\$
    – JRE
    Commented May 24, 2022 at 14:21
  • \$\begingroup\$ @jre can i put a link to the vendor here? don't want to spam... \$\endgroup\$
    – Roger
    Commented May 24, 2022 at 14:22
  • \$\begingroup\$ You're asking a technical question about the stuff, not trying to sell it. \$\endgroup\$
    – JRE
    Commented May 24, 2022 at 14:22

1 Answer 1

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That figure you are talking about is shielding effectiveness. In theory, bigger is better but usually more expensive and bulkier.

In a residential environment it doesn't really change a lot. Especially the difference between material and the kind of shielding is tricky to evaluate and depends on the kind of noise.

In TV signal distribution is usually way more important signal attenuation (how much you lose for each km of cable): here smaller is better.

In general copper is better than aluminum but often it doesn't really matter (unless you need to power a pole amplifier using the cable)

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  • \$\begingroup\$ Well I only have one real concern, I'm depending on Internet on via LTE (and future 5G) I need to pick a cable that has best protection. Have a few concerns about interference in the future. So while pulling the cable, I might as-well put in the right (i.e. best) one. \$\endgroup\$
    – Roger
    Commented May 24, 2022 at 14:30
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    \$\begingroup\$ Technically LTE is on the UHF band used by TV broadcast and comes in straight from the antenna along with the TV signal. There are specific filters to be fit on the line to remove it, cable shielding doesn't really matter. \$\endgroup\$
    – Lorenzo Marcantonio
    Commented May 24, 2022 at 14:32
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    \$\begingroup\$ One thing to note. A poorly installed connector without a proper termination for the shield can reduce those shielding effectiveness (SE) numbers by a lot, going from a theoretical 135 dB to less than 35 dB of SE. \$\endgroup\$
    – SteveSh
    Commented May 24, 2022 at 15:45
  • \$\begingroup\$ These things usually use F connectors which often simply screw over the jacket onto the shield. I agree that a compression fit connector would have better shield integrity \$\endgroup\$
    – Lorenzo Marcantonio
    Commented May 26, 2022 at 6:07

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