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300mW wifi cards

Discussion in 'Networking Issues' started by Mr_X, Aug 22, 2005.

  1. Mr_X

    Mr_X Network Guru Member

    I'm about to buy a 300mW PCMCIA Wifi card: a ZCOM 325HP+ or a Demarc Reliaware 300mW
    But I got a question: what about heat dissipation? Someone told me that these cards generate lots of heat and they shouldn't be used in laptops.
    But I would heard someone that has one of these cards or has experience with one of these cards. Does they really generates so much heat?
  2. littlewhoo

    littlewhoo Network Guru Member

    I have no experience with 300mW cards.

    But I have had severe heat problems with a 200mW card in a laptop. And it seems, that I'm not the only one.

    Most cards have an output power of 30mW and are ok to use in laptops. 100mW cards are radiating considerably more heat, but are still ok for most laptops. 200mW cards are getting really hot and shouldn't be used in most laptops.

    So *presumably* it's even worse with 300mW cards.

    If you can attach a good external antenna to your laptop, this is always a better solution compared to a high powered card.

    - These high powered cards have a huge power consumptions which will quickly deplete the battery of your laptop. The antenna has no influence on the power consumtion of your laptop.

    - Raising the output power is only working in one direction: sending. It doesn't amplify the signal you are receiving. But for a good connection both directions are importand. A better antenna does improve sending and receiving data.

    - With higher outputpower the signal is being amplified, but also the noise. So a stronger signal doesn't neccesarily mean a "better" signal (read better SNR). A better antenna does improve the signal, but doesn't add more noise.

    - Raising the output power has only a tiny influence in the actual signal gain (because it's a logarithmic scale).

    30 mW -> 15 dBm
    100mW -> 20 dBm
    200 mW -> 23 dBm
    300 mW -> 25 dBm

    So you see, that a 300mW card is giving you only a meager 5 dBm compared to a 100mW card. A good antenna can easily give you a gain of 10 dBm or more!

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