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Dipole antenna

Discussion in 'Electronic Basics' started by thejim, Jan 9, 2006.

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  1. thejim

    thejim Guest

    What do we mean by saying that a dipole antenna is electrically short?
     
  2. It means that the antenna is exhibiting capacitive reactance to the
    signal being applied. Adding inductance can cancel that out.
     
  3. Phil Allison

    Phil Allison Guest

    "Anthony Fremont"

    = a congenital autistic cretin


    ** Idiot.

    It means the dipole antenna's width is less than a half wavelength of the
    frequency.



    ** Has no impact on the fact it is "electrically short" and hence an
    inefficient radiator.


    You fucking brainless Texas Twat.




    ......... Phil
     
  4. Speak for yourself phil. Oh, I guess you already are.
    Electrically that is, not necessarily physically. You do know about
    velocity factor, right phil?
    Radiation efficiency has very little to do with any of this. You're way
    out of your element on this one phil, but keep going though. I'd really
    like to see what kind of nonsense you can spew on antenna and
    transmission line theory.
    Who's stalking now?
     
  5. Phil Allison

    Phil Allison Guest

    "Anthony Fremont"
    = a congenital autistic cretin

    ** FUCKING Idiot.


    ** WRONG - FUCKHEAD.


    ** IRRELEVANT to the antenna - FUCKHEAD !!


    ** WRONG - FUCKHEAD !!!

    Fremont is a PIG IGNORANT ASSHOLE.

    A vile, anencephalic, autistic Texas Twat.

    Millions of these evil PUKEs down there.


    ]


    ......... Phil
     
  6. It's still true phil, no matter how many times you reply to it with
    ad-hominem attacks. I can only hope that someone else that knows
    something about antennas will step into this, lest some poor newbie
    believe your nonsense.
    That's precisely how it works. It has practically nothing to do with
    physical length other than that's one of the multipliers used when
    calculating the electrical length.
    Really now phil, you know even less than I suspected. Velocity factor
    applies to all of it, especially the antenna itself.
    Where is your disputing evidence phil?
    Why don't you try providing some facts phil? Instead of name calling,
    why don't you show us all some evidence to back up your libelous claims?
    I guess that was it. Typical spastic fit when you don't have an answer,
    huh phil? I bet you have never made a single transmitting antenna for
    HF or VHF. If you had, you'd probably be keeping your mouth shut now.
     
  7. It means that it has a resonant frequency a little higher than what is
    being applied to it.
     
  8. Thanks John. I would add for the OP's benefit that dipoles cut using
    the standard formula will always come out electrically long since the RF
    doesn't travel at the full speed of light thru the antenna elements.
    Therefore they will need to be trimmed to resonance to accommodate that
    fact. A great number of other things will also affect this process
    (basically anything that you can think of ;-)

    One major player that must be considered is the velocity factor of the
    material used for constructing the antenna elements. For example,
    dipole elements made from insulated wire will exhibit a different
    velocity factor if the insulation is removed vs. leaving it on.
    Therefore, they will need to be trimmed to different lengths to obtain
    resonance at the same frequency.
     
  9. Phil Allison

    Phil Allison Guest

    "Anthony Fremont" = a congenital autistic cretin

    ** No it is not - and you are an IDIOT.



    ** WRONG - IDIOT .


    ** WRONG.



    ** Any good text of antenna theory will confirm what an the term
    "electrically short" antenna refers to.

    They can be externally tuned to resonance but still have less radiation
    efficiency that a naturally resonant antenna.



    ** The PIG IGNORANCE and PIG ARROGANCE are GLARING .




    ** YOU are posting all the evidence - ASSHOLE.



    ** PISS OFF - you know nothing, libelling SCUMBAG !





    ......... . Phil
     
  10. Phil Allison

    Phil Allison Guest

  11. Leave it to you to find the obscure, extreme case to try and save some
    face. In this particular case you are right, efficiency is extremely
    hampered by the incredible shortness of the antenna and inductance will
    not make the antenna work any better, it would make a transmitter very
    happy though. Why you immediately assume the OP is referring to MF
    antennas is beyond me.
     
  12. Phil Allison

    Phil Allison Guest

    "Anthony Fremont" = AUTISTIC LYING PIG



    ** WRONG AGAIN - IDIOT !!!!!



    ** WRONG AGAIN - IDIOT !!!!!

    The exact same concepts apply to "electrically short" VHF and UHF antennas.

    http://www.ee.surrey.ac.uk/Personal/D.Jefferies/antennexarticles/radimp.htm



    ** PISS OFF - YOU BLOODY CRETIN !



    ......... Phil
     
  13. Do you really think that people don't see the butcher job you do when
    snipping the context out of everything as you trim. Or the way you
    continually twist things by interjecting your own set of completely
    fabricated working conditions in some childish attempt to erase the
    lunacy from some previous foolish statement you made. Face it phil, you
    don't know jack about antennas OR transmission lines, why can't you
    simply admit that?

    You can keep saying that I'm wrong, and call me as many names as you can
    think of, but it won't change the truth. To the best of my knowledge
    all of the statements I have made are true and correct. I've built
    plenty of antennas phil. At least plenty enough of them to know that if
    you think that you will get by with book theory and strictly applied
    formulas to do it, you're gonna be on a short road to failure. I'm not
    saying that I'm an expert on the subject, but I do know something about
    it.

    FYI, I own a few well worn ARRL Handbooks (including my first one from
    1974), the Antenna Compendium and many other radio THEORY books
    including a Sam's Radio Handbook. I have also APPLIED some of this
    material, that's why I know how far theory can deviate from reality on
    this subject. Now tell us all again philth just how much education and
    experience you have regarding the subject, dumbass.

    PS: I love my MFJ-259B. ;-)
     
  14. Phil Allison

    Phil Allison Guest

    "Anthony Fremont"

    = Lying, autistic, Texas asshole


    ** So you are fuckwit radio ham ??

    Explains it all really.



    ........ Phil
     
  15. http://www.ee.surrey.ac.uk/Personal/D.Jefferies/antennexarticles/radimp.htm

    Now tell me something I don't already know. Given that the OP didn't
    specify that he was talking about very short antennas (1/10 lambda or
    less), I naturally didn't jump to the conclusion that he was. I,
    perhaps wrongly, assumed he wanted to know what the term "electrically
    short" meant. In these extreme cases that you like to bring up, the
    efficiency is bad and it pretty much stays that way regardless of what
    you attempt. Capacity plates (or hats as many like to call them) and
    loading coils help to match the impedance and/or improve bandwidth, but
    they still radiate like crap (orders of magnitude more poorly) compared
    to even a 1/4 wave. Just tune around the 160m or even 80m bands
    listening for the mobile stations. They're there, but just try to hear
    them.
     
  16. "Phil Allison" scrawled
    You didn't answer my question.
     
  17. Phil Allison

    Phil Allison Guest

    "Anthony Fremont"


    ** Failed the test of relevance nor made any sense.


    YOU can go to HELL - IDIOT.




    ......... Phil
     
  18. Phil Allison

    Phil Allison Guest

    "Anthony Fremont"


    ** So you are know nothing, fuckwit radio ham ??

    Explains it all really.




    ........ Phil
     
  19. IKYABWAI YAAAWWWWNNNNNNN You're really getting boring now philth.
    Even darkmatter was able to put up a more fact based argument than you.
    Not to mention that Boki beats you hands down on sentence construction
    and clarity.

    So how would being a ham "explain it all"?

    HAND
     
  20. Phil Allison

    Phil Allison Guest

    "Anthony Fremont"

    = autistic, illiterate bloody IDIOT


    ** So you are *know nothing, fuckwit radio ham * ??

    Explains it all really.





    ........ Phil
     
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