Antenna For Frequency Sweep 10Mhz to 100Mhz

Discussion in 'Wireless & RF Design' started by Tigera, Apr 20, 2016.

  1. Tigera

    Thread Starter New Member

    Apr 20, 2016
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    Hello,
    I need to transmit 10 Mhz to 100 Mhz Frequency Sweep equal in all directions so the antenna gain is about 0 db, but the thing is really matter is the antenna size.
    for 10 Mhz---- λ=30 M ---- (λ/4) = 7.5 M
    for 100 Mhz---- λ=3 M ----- (λ/4)= 75 cm

    Because the frequency varies from 10 Mhz to 100 Mhz , the antenna lenght varies from 7.5 m to 75 cm.

    What kind of Antenna Should I USE???
     
  2. SLK001

    Well-Known Member

    Nov 29, 2011
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    Ain't gonna happen.
     
  3. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Why would you like to sweep 10 - 100 Mhz using a transmitter?

    A wide band transmitter antenna can not be made.
    A vertical antenna must have odd quarters on the lenght.
    An 7.5 Meter antenna will work on 1/4 λ,3/4λ,5/4λ,7/4λ and 9/4λ or 10,30,50,70 and 90 Mhz.
    On the even quarters the SWR will be the worst, so at 2/4λ,4/4λ,6/4λ,8/4λ and 10/4λ or 20,40,60,80 and 100 Mhz.
    You can not sweep the whole range from 10 to 100 Mhz with only one antenna.

    Bertus
     
  4. Tigera

    Thread Starter New Member

    Apr 20, 2016
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    Thanks Guys.
     
  5. DickCappels

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  6. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    No idea about the power output at final stage but you would be crossing several different bands for very dissimilar services. No matter where in the world you will do, the situation is similar. Have you the respective authorizations to do it?

    Omnidirectional you say, good to affect as much people as you can, methinks.
     
  7. KL7AJ

    AAC Fanatic!

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  8. bertus

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  9. DickCappels

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    Nobody said it was going to be small :)

    Using any of these antennas over a decade range will require connection for the sensitivity variation off if any kind of calibration is needed.
     
  10. Tigera

    Thread Starter New Member

    Apr 20, 2016
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  11. DickCappels

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    If you don't mind tuning as the frequency changes, this can be a good solution.
     
  12. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Again, Why do you want to transmit from 10 to 100 Mhz sweeping?
    There are many shortwave radio stations and amateur radio bands in that range.

    Bertus
     
  13. Tigera

    Thread Starter New Member

    Apr 20, 2016
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    It's for a molecular frequency resonance system,and continuously make different objects and material to resonance just for exp experimental use.(Like breaking glass by resonance frequency).Actually The Frequency range may be more than 10 Mhz to 100 Mhz.

    Is there any voltage/frequency controlled Antenna Tuner (Like VCO's,AGC(automatic gain control),......) ??

    So The Tuner automatically tuning as frequency changes.
     
  14. bertus

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  15. Tigera

    Thread Starter New Member

    Apr 20, 2016
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    I Know nothing about NMR and Physics , but one of my friend asked me to design a system to radiate a frequency sweep. He explained about it but I don't get it :) and aslo I'm not sure even it is about NMR ...

    It's not important, the only issue is the radiating the frequency sweep.

    the frequency sweep circuit is simple but the main problem is the antenna!!
     
  16. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    What you are trying to do is like pseudo science.

    You will not get materials into resonance without a strong magnetic field.

    Bertus
     
  17. Wendy

    Moderator

    Mar 24, 2008
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    Not to mention having several government services hunting you down. Military and civilian authorities look very poorly on jamming, which is what you are proposing. The only way to not get into trouble, regardless of your country of origin, is a RF shielded room (AKA Faraday cage).
     
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