How Much Power for the Antenna?

Discussion in 'General Electronics Chat' started by sjgallagher2, Dec 3, 2013.

  1. sjgallagher2

    Thread Starter Member

    Feb 6, 2013
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    How do I determine how much power to input to a dipole antenna, when I know the range? I've heard 1/4 watt can transmit for a mile, but how do you get that without practical experimenting?
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Learn to use a Path Loss Calculator like this one.

    You have to consider frequency, TX and RX antenna gains, coax losses, TX power, RX sensitivity, and distance for starters
     
  3. Papabravo

    Expert

    Feb 24, 2006
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    And there are other variables including time of day, season of the year, and position in the 11-year sunspot cycle. Right now we are supposed to be at the Solar Max, but sadly ole Sol is not cooperating.
     
  4. sjgallagher2

    Thread Starter Member

    Feb 6, 2013
    111
    7
    Thanks Mike, you seem to know a lot about radio and you've been a huge help to me lately! Another question though, as far as transmission lines go. If I have a transmitter circuit, running at 900MHz, that leads straight to the antenna, should I take the output of the circuit and connect it to an RG8X coax cable? What kind of connector do I need at 900 MHz? Should I use a different type of cable?
     
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Usually there is at least a short length of coax between a transmitter or receiver and its associated antenna. At 900MHz, I would be looking at BNC,TNC or SMA connectors.

    Don't forget that an antenna needs to approximate a center-fed 1/2 wavelength dipole; a 1/4 wavelength monopole without a ground plane (or the other 1/4 wavelength of the dipole) is a crappy antenna.
     
  6. sjgallagher2

    Thread Starter Member

    Feb 6, 2013
    111
    7
    Thanks a million Mike! You're a huge help
     
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