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Re: Need clarification on RF related concepts

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On 10/17/2016 1:27 AM, dakupoto@gmail.com wrote:
> On Sunday, October 16, 2016 at 10:36:17 AM UTC-4, Tauno Voipio wrote:
>> On 16.10.16 09:44, dakupoto@gmail.com wrote:
>>> Could some electronics guru please help ?
>>> I am a bit rusty on some RF concepts so I
>>> request some clarifications from the gurus
>>> here.
>>>
>>> By definition, a 4:1 balun has 4 times
>>> the impedance on the balamced side as the
>>> unbalanced side. For any inductor, the
>>> impedance is based on the reactance, which
>>> in turn is based on the frequency of
>>> operation.
>>>
>>> So, what frequency is being considered
>>> here ? The reason I ask is that a balun
>>> could be used as broadband impedance
>>> matching device. Thanks in advance for
>>> your help.
>>
>> A balun is a matching element between a balanced and
>> an unbalanced transmission line. The 4:1 balun is
>> in its simplest form an auto-transformer (2 identical
>> windings connected in series). The center tap is connected
>> to the unbalanced side ground, one of the ends is
>> connected to both the unbalanced non-grounded wire and
>> one of the balanced wires. The remaining end of the transformer
>> is connected to the remaining balanced line wire.
>>
>> There can be an impedance transformation of 4:1 using
>> a similar transformer, but connecting the center tap to
>> the unbalanced non-grounded line and connecting the
>> common end of the transformer to ground wires of both
>> low-impedance and high-impedance line. The non-grounded
>> high-impedance line it taken from the top end of the
>> auto-transformer.
>>
>> A similar effect can be achieved using transmission lines.
>> If we have a feed of impedance Z0, we can connect it to
>> a pair of lines of impedance 2*Z0 in parallel. If the
>> other ends of the lines are connected in series, there
>> will be a connection of impedance 4*Z0, but there is
>> a requirement to prevent current flow outside the transmission
>> lines, to prevent part of the circuit being short-circuited.
>> This can be achieved by coiling the lines on a suitable magnetic
>> core, creating an auto-transformer on low frequencies and
>> a transmission-line transformer on high frequencies.
>>
>> Google gave pretty good responses to 'trnasmission-line transformer'.
>>
>> --
>>
>> -TV
>
> Thanks to each of you for the insightful comments and
> jogging my memory. I am sorry I must have posted on the
> day when Phil's constipation was at its worst.
>
  BTW, if you want a book that covers Baluns, Ununs and Transmision Line 
transformers with dozens of built examples including frequency response 
and loss curves, I recommend, 'Transmision Line transformers' by Jerry 
Sevick. Also includes many different ratio transformers.
                                               Mikek

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Need clarification on RF related concepts dakupoto@gmail.com - 2016-10-15 23:44 -0700
  Re: Need clarification on RF related concepts amdx <nojunk@knology.net> - 2016-10-16 04:37 -0500
  Re: Need clarification on RF related concepts Phil Allison <pallison49@gmail.com> - 2016-10-16 05:14 -0700
    Re: Need clarification on RF related concepts amdx <nojunk@knology.net> - 2016-10-16 08:04 -0500
  Re: Need clarification on RF related concepts Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-10-16 17:36 +0300
    Re: Need clarification on RF related concepts dakupoto@gmail.com - 2016-10-16 23:27 -0700
      Re: Need clarification on RF related concepts amdx <nojunk@knology.net> - 2016-10-18 08:44 -0500
        Re: Need clarification on RF related concepts Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2016-10-18 11:06 -0400
        Re: Need clarification on RF related concepts "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-11-07 13:38 -0500
          Re: Need clarification on RF related concepts George Herold <gherold@teachspin.com> - 2016-11-07 11:00 -0800
            Re: Need clarification on RF related concepts "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-11-09 18:35 -0500
              Re: Need clarification on RF related concepts Jeff Liebermann <jeffl@cruzio.com> - 2016-11-09 19:59 -0800
                Re: Need clarification on RF related concepts "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-11-12 08:46 -0500
          Re: Need clarification on RF related concepts "nuny@bid.nes" <Alien8752@gmail.com> - 2016-11-07 11:09 -0800
            Re: Need clarification on RF related concepts "Michael A. Terrell" <mike.terrell@earthlink.net> - 2016-11-09 18:22 -0500
  Re: Need clarification on RF related concepts Tim Wescott <tim@seemywebsite.really> - 2016-10-16 14:28 -0500
  Re: Need clarification on RF related concepts rickman <gnuarm@gmail.com> - 2016-10-17 04:04 -0400
    Re: Need clarification on RF related concepts "Tim Williams" <tiwill@seventransistorlabs.com> - 2016-10-18 07:00 -0500
      Re: Need clarification on RF related concepts Jeroen Belleman <jeroen@nospam.please> - 2016-10-18 16:45 +0200
  Re: Need clarification on RF related concepts Jasen Betts <jasen@xnet.co.nz> - 2016-10-17 09:43 +0000

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