Re: Problem with Dipole Radiation and Relativity

From	Sylvia Else <sylvia@not.at.this.address>
Newsgroups	sci.physics, sci.physics.relativity
Subject	Re: Problem with Dipole Radiation and Relativity
Date	2015-10-24 00:03 +1100
Message-ID	<d8uph2Fb3haU1@mid.individual.net> (permalink)
References	<pan.2015.09.21.18.05.41@localhost.localdomain>

Cross-posted to 2 groups.

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On 22/09/2015 4:05 AM, Fabian Russell wrote:
> An observer moving with velocity 0.6c approaches a radiating dipole
> antenna in a direction perpendicular to the dipole axis:
>
>
>
>             |
>             |        direction of motion
>             |
>             \/
>
>
>
> ----------   ----------  stationary dipole
>            | |
>            | |
>
>
>
> Assume the dipole is resonant in its own frame with frequency F.
>
> The moving observer thus sees a frequency of 2F.
>
> The radiation pattern will also be transformed.  The calculations
> in textbooks show the distorted dipole pattern that is observed
> in the moving frame to be of the following form:
>
> http://s12.postimg.org/qq52njtel/doppler.png
>
>
> Now, here is the problem.
>
> Since the dipole axis is perpendicular to the motion it will not
> be Lorentz contracted.  The moving observer therefore sees an
> antenna length that is is too long for its frequency.  The moving
> observer sees a *non-resonant* dipole.
>
> The pattern of a non-resonant dipole is different from a resonant
> dipole.  The following image shows a resonant (F) and non-resonant (2F)
> dipole pattern:
>
> http://s24.postimg.org/l9yhlpik5/dipole_rad.png
>
>
> Why doesn't the moving observer see a distorted dipole pattern
> with TWO LOBES instead of ONE LOBE?  Since the moving observer
> sees a frequency of 2F from an antenna that is resonant at F
> the transform should be done on the non-resonant, two-lobed,
> pattern.
>
> What is the resolution of this apparent problem?
>

This presuppose that one knows how to calculate the resonant frequency 
of a moving dipole.

So how does one calculate the resonant frequency of a moving dipole?

Special relativity gives a clue. Calculate the resonant frequency of a 
stationary dipole, and then transform into a moving frame.

If one does it that way, of course, there's no problem that needs resolving.

So the "problem", such as it was, was really just created by an 
incorrect approach to calculating the resonant frequency.

Sylvia.

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Thread

Problem with Dipole Radiation and Relativity Fabian Russell <root@localhost.localdomain> - 2015-09-21 18:05 +0000
  Re: Problem with Dipole Radiation and Relativity Fabian Russell <root@localhost.localdomain> - 2015-09-22 03:04 +0000
  Re: Problem with Dipole Radiation and Relativity Fabian Russell <root@localhost.localdomain> - 2015-09-22 04:42 +0000
  Re: Problem with Dipole Radiation and Relativity Tom Roberts <tjroberts137@sbcglobal.net> - 2015-09-21 23:54 -0500
    Re: Problem with Dipole Radiation and Relativity Fabian Russell <root@localhost.localdomain> - 2015-09-22 05:28 +0000
  Re: Problem with Dipole Radiation and Relativity Fabian Russell <root@localhost.localdomain> - 2015-09-22 05:02 +0000
  Re: Problem with Dipole Radiation and Relativity "Paul B. Andersen" <relativity@paulba.no> - 2015-09-28 12:24 +0200
    Re: Problem with Dipole Radiation and Relativity HGW <xxx@....> - 2015-09-29 07:47 +1000
      Re: Problem with Dipole Radiation and Relativity Tom Roberts <tjroberts137@sbcglobal.net> - 2015-09-28 22:06 -0500
        Re: Problem with Dipole Radiation and Relativity noTthaTguY <abu.kuanysh05@gmail.com> - 2015-09-29 11:31 -0700
          Re: Problem with Dipole Radiation and Relativity noTthaTguY <abu.kuanysh05@gmail.com> - 2015-09-29 19:52 -0700
        Re: Problem with Dipole Radiation and Relativity HGW <xxx@....> - 2015-10-03 08:26 +1000
          Re: Problem with Dipole Radiation and Relativity Sam Wormley <swormley1@gmail.com> - 2015-10-02 17:47 -0500
            Re: Problem with Dipole Radiation and Relativity Henry Wilson <HW@.....> - 2015-10-05 04:47 +1100
              Re: Problem with Dipole Radiation and Relativity Sam Wormley <swormley1@gmail.com> - 2015-10-04 18:00 -0500
                Re: Problem with Dipole Radiation and Relativity Maciej Woźniak <mlwozniak@wp.pl> - 2015-10-05 09:46 +0200
                Re: Problem with Dipole Radiation and Relativity Sam Wormley <swormley1@gmail.com> - 2015-10-05 11:48 -0500
                Re: Problem with Dipole Radiation and Relativity Maciej Woźniak <mlwozniak@wp.pl> - 2015-10-05 20:19 +0200
                Re: Problem with Dipole Radiation and Relativity Sam Wormley <swormley1@gmail.com> - 2015-10-05 13:28 -0500
                Re: Problem with Dipole Radiation and Relativity Maciej Woźniak <mlwozniak@wp.pl> - 2015-10-05 21:16 +0200
                Re: Problem with Dipole Radiation and Relativity Henry Wilson <HW@.....> - 2015-10-05 20:01 +1100
                Re: Problem with Dipole Radiation and Relativity Sam Wormley <swormley1@gmail.com> - 2015-10-05 11:52 -0500
                Re: Problem with Dipole Radiation and Relativity Henry Wilson <HW@.....> - 2015-10-06 04:55 +1100
                Re: Problem with Dipole Radiation and Relativity Sam Wormley <swormley1@gmail.com> - 2015-10-06 07:59 -0500
                Re: Problem with Dipole Radiation and Relativity noTthaTguY <abu.kuanysh05@gmail.com> - 2015-10-06 11:34 -0700
                Re: Problem with Dipole Radiation and Relativity "Paul B. Andersen" <relativity@paulba.no> - 2015-10-06 20:55 +0200
                Re: Problem with Dipole Radiation and Relativity HGW <xxx@....> - 2015-10-07 07:50 +1100
                Re: Problem with Dipole Radiation and Relativity "Paul B. Andersen" <relativity@paulba.no> - 2015-10-07 11:15 +0200
                Re: Problem with Dipole Radiation and Relativity HGW <xxx@....> - 2015-10-06 14:52 +1100
                Re: Problem with Dipole Radiation and Relativity Sam Wormley <swormley1@gmail.com> - 2015-10-06 19:15 -0500
                Re: Problem with Dipole Radiation and Relativity HGW <xxx@....> - 2015-10-09 07:36 +1100
              Re: Problem with Dipole Radiation and Relativity Odd Bodkin <bodkinodd@gmail.com> - 2015-10-05 07:39 -0500
                Re: Problem with Dipole Radiation and Relativity Henry Wilson <HW@.....> - 2015-10-06 05:03 +1100
                Re: Problem with Dipole Radiation and Relativity Odd Bodkin <bodkinodd@gmail.com> - 2015-10-05 14:20 -0500
                Re: Problem with Dipole Radiation and Relativity HGW <xxx@....> - 2015-10-06 15:02 +1100
                Re: Problem with Dipole Radiation and Relativity Odd Bodkin <bodkinodd@gmail.com> - 2015-10-06 07:48 -0500
                Re: Problem with Dipole Radiation and Relativity HGW <xxx@....> - 2015-10-07 07:40 +1100
                Re: Problem with Dipole Radiation and Relativity Odd Bodkin <bodkinodd@gmail.com> - 2015-10-06 17:59 -0500
                Re: Problem with Dipole Radiation and Relativity Sam Wormley <swormley1@gmail.com> - 2015-10-06 19:17 -0500
                Re: Problem with Dipole Radiation and Relativity HGW <xxx@....> - 2015-10-09 07:34 +1100
                transitive property noTthaTguY <abu.kuanysh05@gmail.com> - 2015-10-08 12:33 -0700
          Re: Problem with Dipole Radiation and Relativity Tom Roberts <tjroberts137@sbcglobal.net> - 2015-10-08 10:42 -0500
            Re: Problem with Dipole Radiation and Relativity HGW <xxx@....> - 2015-10-09 08:14 +1100
      Re: Problem with Dipole Radiation and Relativity "Paul B. Andersen" <relativity@paulba.no> - 2015-09-29 11:00 +0200
  Re: Problem with Dipole Radiation and Relativity Sylvia Else <sylvia@not.at.this.address> - 2015-10-24 00:03 +1100

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