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Wideband antennae for Spec Analyzer

Discussion in 'Electronic Design' started by Jim Jeffery, Mar 27, 2011.

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  1. Jim Jeffery

    Jim Jeffery Guest

    I have just purchased a secondhand Advantest 3465, 100KHz to 8MHz
    spectrum analyzer.

    Well, that was expensive, so I can't really afford any factory-made
    antennae at this time.

    Can anyone please advise how I can make a wideband antenna, or limited
    series of same, that will work within this range for monitoring of
    environmental EMI?

    Hopefully, a little more than just hanging a wire off the input. The
    relevant specs are below.

    **********

    Measurement range: +30 dBm to avg. display noise level
    Maximum safe input:
    Avg. continuous power (input ATT = 10 dB): +30 dBm (1 W)
    DC input: 0 V
    Display range: 10 × 10 div
    Log ;10, 5, 2, 1, 0.5/div
    Linear; 10% of reference range/div
    Reference level range:
    Log; –105 dBm to +60 dBm (0.1 dB steps)
    Linear; 1.25 µV to 223 V (approx. 1% of full–scale steps)
    Input attenuator range: 0 to 70 dB (10 dB steps)

    **********

    Many thanks,

    Jim Jeffery
     
  2. I think you meant 8Ghz.

    These spectran antennas look good.
    <http://www.spectran.com/EMC_Test_Antenna.shtml#1>
    The problem is you need a calibrated/flat response from the antenna.
    I would rent, as Jim pointed out.


    Cheers
     
  3. Jim Jeffery

    Jim Jeffery Guest

  4. Guest

    Antennas are easy. Calibrating them is not. You're going to need more than
    one for this range (assuming you meant 8GHz), though.
     
  5. Jim Jeffery

    Jim Jeffery Guest


    Great links. How about some less rigous methods for those who may not
    need calibration or directionality?

    1. A number of concentric circles glued on a piece of perspex. Each
    would have a gap so as not to be complete, and be oriented at 180
    degress from the next one. Feed would be from one end of each, and
    wired in series.

    2. An array of a few dozen pieces of brass welding rod (different
    lengths) with one end of each soldered to a copper base plate. Or
    telescoping antennae if they need to be adjustable.

    Worth a try or too simplistic?

    Jim Jeffery
     
  6. Rich Grise

    Rich Grise Guest

    There are "fractal" antennas, but the only thing I know about them is
    that they're fractal. :)

    Good Luck!
    Rich
     
  7. Jim Jeffery

    Jim Jeffery Guest

  8. axolotl

    axolotl Guest

    You might want to look at Wilmar Robert's measurement antennas.

    http://glendash.com/Archives/Roberts - FCC Antennas.pdf

    Kevin Gallimore
     
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