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effective radiated power

Discussion in 'Electronic Repair' started by [email protected], May 17, 2007.

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  1. Guest

    I can't remember my formulas. If I have a transmitter that puts 1 watt
    into a beam antenna that has a gain of 8.0DB what is my EFR? Please
    show the work. I need to be able to demonstrate this to a customer.
    Thanks alot.
    Lenny Stein
    Barlen Electronics.
  2. Arfa Daily

    Arfa Daily Guest

    Just show him the calculator on this site

    Should do the job.

  3. Charles

    Charles Guest

    Take the anti-log of 0.8 (in this case).

    based on:

    8 dB = 10 x log (X/1)

    divide both sides by 10 and then take the anti-log (10^x key).
  4. Lenny-

    Charles' method should work for you. If a customer asks, you need to
    know more about the antenna's gain - is it compared to an isotropic
    antenna (dBi) or compared to a dipole (dBd)? Note that 0 dBd = 2.1 dbi.
    An antenna with isotropic gain of 8 dBi would have a gain of 5.9 dB with
    respect to a dipole.

    The isotropic gain is useful for calculating field strength at a
    distance, but gain with respect to a dipole is easier to measure!

  5. Arfa Daily

    Arfa Daily Guest

    The calculator that I pointed Lenny at does it for dBi and dBd. A lot easier
    to just show your customer something that goes ahead and does the job,
    rather than faffing about in front of him with a calculator, working with a
    formula and numbers that you're not totally easy with ...

  6. Charles

    Charles Guest

    He posted "Please show the work."
  7. Arfa Daily

    Arfa Daily Guest

    That is true, but I assumed that he asked this such that he could
    re-familiarise himself with the math so that he would be able to demonstrate
    to his customer how to work it out. Based on my many years of dealing with
    customers, and making myself look dumb on occasion by trying to explain
    something that I was not properly familiar with, I just felt that it might
    look slicker to the customer to be able to just enter the figures and see
    the results, for both comparison schemes, instantly shown. If he really
    wants to go down the route of doing it all himself, Google will turn up many
    hits if he just enters " Antenna ERP " as the search string.

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