Re: long antenna

From	gilber34 <fafa@invalid.com>
Newsgroups	sci.physics
Subject	Re: long antenna
Date	2015-11-18 20:42 -0600
Organization	Aioe.org NNTP Server
Message-ID	<n2jcuf$9qr$1@speranza.aioe.org> (permalink)
References	<d82a6d99-39d1-4eb7-9aa0-4ed38641537a@googlegroups.com> <n2fsm5$ms8$1@speranza.aioe.org> <4736856.kWDMch3Bm0@PointedEars.de> <n2ivpn$gh9$1@speranza.aioe.org> <fddvhc-vob.ln1@mail.specsol.com>

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On 11/18/2015 5:15 PM, jimp@specsol.spam.sux.com wrote:
> gilber34 <fafa@invalid.com> wrote:
>> On 11/18/2015 3:56 PM, Thomas 'PointedEars' Lahn wrote:
>>> Odd Bodkin wrote:
>>>
>>>> On 11/17/2015 12:42 PM, RichD wrote:
>>>>> During my workout yesterday, I attached a 3 meter
>>>>> extension to the earphone cord of my radio, as I
>>>>> wanted to place it at a distance.
>>>>> The cord is the antenna.
>>>>>
>>>>> I was indoors, where the reception is usually crummy.
>>>>> I figured the longer line should improve performance,
>>>>> right?  No!  The reception was barely decipherable.
>>>>>
>>>>> Can anyone explain the physics here?
>>>>
>>>> Yeah, it's pretty simple. The earphone is attached to an OUTPUT of the
>>>> radio. The only valuable place to stick an antenna is on an INPUT to the
>>>> radio.
>>>
>>> Wrong.
>>>
>>>> Signals-->||-->Tuner-->Amplifier-->Analog driver-->||-->Earphones
>>>>               <-----------  Radio  ------------------->
>>>>
>>>> See where the antenna goes?
>>>
>>> Not only is your answer wrong, you also missed the point of the question.
>>>
>>> As the OP indicated, earphone (also: headphone) cords contain wires which
>>> can serve as antennas.
>>
>> .....well, they do connect to the Head which serves as the big resonae
>> cavity Antenna. a large round semi conductive salt vat on your sholders,
>> full of liquid up in the air.
>
> Nope.
>
>>   [They certainly do with smartphones (from where I
>>> know the technology): Once you have plugged the headphones into the
>>> smartphone, you can start a radio app to tune in to FM (frequency
>>> modulation) radio channels (*without an Internet connection*). [0]
>>> It stands to reason to use the same technology elsewhere.]
>>>
>>> How does radio, how does an antenna work?  Radio is based on the
>>> transmission and reception of radio waves carrying information piggybacked
>>> on them through modulation of them.
>>
>> no piggies were harmed...
>>
>>
>>> Therefore, the
>>> longer line does _not_ improve reception quality of a particular radio
>>> channel (its station transmitting at a particular frequency) to begin with.
>>
>> that is, in general, a wrong statement.  larger capture area means more
>> signal power.
>
> Nope; grossly oversimplified to the point of being wrong.

yep,  oversimplified for sure.   Need the frequency band.

>
>>> I also think that the longer the line the more likely that there is
>>> interference, i.e. alternating, partially canceling electrical currents
>>> induced at different points of the cable as the (peak of the) radio waves
>>> can hit the cable at those points at different times, and interference from
>>> other sources.
>>
>> they dont "hit" the cable.
>
> They sure don't go around the cable.

"hit" an antenna is not used in the industry,
look it up in Kraus, its a summation of currents, etc. etc.


>>> Finally, electrical resistance of a conductor R = ρl∕A,
>>> where ρ is the material-dependent electrical resistivity and A is the cross-
>>> sectional area, is proportional to the length l of the conductor [8], so the
>>> signal that reaches the tuner should become weaker as the cable length
>>> increases.
>>
>> wrong.  (match the impeadance, Hint: it is a complex term. lots of free
>> programs out there on antenna design if you are interested.)
>
> About the only thing correct so far.
>
>>> However, I understand that there are also traveling wave antennae that are
>>> nonresonant, like random wire for receiving shortwave radio. [9]

one can use an antenna with a preamp and forget matching, however the 
preamp will be a mixer, with the LO supplied by FM, TV stations or other 
if around, providing inteference.


  So it
>>> appears to depend on the frequencies that one wants to receive.  I would
>>> like someone with experience in radio technology to add their expertise
>>> here.  And please, CMIIW.
>>>
>>>
>>> PointedEars
>>
>> depends upon what frequency band you are looking at.
>> FM - you usally will get blasted out by high power stations, over
>> loading your very cheap chinese receiver.
>
> FM stations are not usually high power as the FM band is essentially
> line of sight and does not depend on either ground wave or sky wave
> propagation as AM does.
>
>

not so, FM power is HUGE.
and remember FM is frequency is 200 times AM, and probagation is very 
different, still good compaired to 800 MHz. BUT the main thing with FM 
is that system was designed so one could use cheap low cost receivers, 
so transmit power is high, and the receivers do not have much 
selectivity, and rely on an effect called "capture". if you have two 
stations on the same frequency, but one is 10Db lower in power, the 
higher power one will swamp out the low power one, and you will hear 
only the high power one. (not so with AM, you hear both)

he said he was listening to FM, so he is in a city,

but break out your spectrum analyser and see how huge the FM station 
power is, larger than any other, except for some TV channels

I would do it and send a photo, but my analyser when last turned on, let 
out some smoke in the back, and no workie now. (smoked a resistor in the 
power section somewhere)

Thread

long antenna RichD <r_delaney2001@yahoo.com> - 2015-11-17 10:42 -0800
  Re: long antenna Odd Bodkin <bodkinodd@gmail.com> - 2015-11-17 12:46 -0600
    Re: long antenna Poutnik <poutnik4nntp@gmail.com> - 2015-11-17 20:10 +0100
    Re: long antenna jimp@specsol.spam.sux.com - 2015-11-17 20:28 +0000
      Re: long antenna benj <nobody@gmail.com> - 2015-11-17 16:59 -0500
    Re: long antenna Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-11-18 22:56 +0100
      Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-18 16:57 -0600
        Re: long antenna jimp@specsol.spam.sux.com - 2015-11-18 23:15 +0000
          Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-18 20:42 -0600
            Re: long antenna jimp@specsol.spam.sux.com - 2015-11-19 05:29 +0000
              Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-19 08:54 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-19 18:44 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-22 15:32 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-22 23:16 +0000
            Re: long antenna HVAC <mr.hvac@gmail.com> - 2015-11-19 06:59 -0800
              Re: long antenna benj <none@gmail.com> - 2015-11-19 20:02 -0500
      Re: long antenna benj <none@gmail.com> - 2015-11-19 01:36 -0500
  Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-17 13:28 -0600
  Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-17 14:04 -0800
    Re: long antenna jimp@specsol.spam.sux.com - 2015-11-17 22:35 +0000
      Re: long antenna benj <nobody@gmail.com> - 2015-11-17 19:28 -0500
        Re: long antenna Timo <timo@physics.uq.edu.au> - 2015-11-17 17:18 -0800
          Re: long antenna RichD <r_delaney2001@yahoo.com> - 2015-11-24 11:39 -0800
            Re: long antenna benj <none@gmail.com> - 2015-11-24 15:12 -0500
              Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 09:21 -0600
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 10:05 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 20:05 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 18:39 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-27 01:46 +0000
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 19:55 +0000
            Re: long antenna jimp@specsol.spam.sux.com - 2015-11-24 20:04 +0000
              Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-24 16:33 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-24 22:58 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 09:11 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 19:42 +0000
                Re: long antenna "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2015-11-26 11:57 -0800
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 14:52 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 21:12 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 18:58 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-27 01:37 +0000
                Re: long antenna benj <none@gmail.com> - 2015-11-26 23:45 -0500
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-27 01:01 -0600
                Re: long antenna "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2015-11-26 23:31 -0800
                Re: long antenna benj <nobody@gmail.com> - 2015-11-27 11:34 -0500
                Re: long antenna "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2015-11-27 09:58 -0800
                Re: long antenna benj <nobody@gmail.com> - 2015-11-27 11:46 -0500
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-28 16:42 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-28 22:58 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 07:46 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-30 19:01 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 14:12 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-30 20:43 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 17:41 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-12-01 00:15 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 20:23 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-12-01 06:21 +0000
                Re: long antenna benj <none@gmail.com> - 2015-11-30 15:22 -0500
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-30 20:48 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 17:16 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-30 23:52 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-30 19:59 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-12-01 02:16 +0000
                Re: long antenna benj <none@gmail.com> - 2015-11-30 19:20 -0500
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-27 18:53 +0000
              Re: long antenna benj <none@gmail.com> - 2015-11-25 00:08 -0500
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-25 06:13 +0000
  Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-18 16:25 -0800
  Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-19 16:08 -0800
    Re: long antenna jimp@specsol.spam.sux.com - 2015-11-20 00:40 +0000
      Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-20 15:51 -0800
        Re: long antenna jimp@specsol.spam.sux.com - 2015-11-21 00:34 +0000
          Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-21 14:37 +0000
            Re: long antenna jimp@specsol.spam.sux.com - 2015-11-21 19:32 +0000
              Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-22 14:50 +0000
                Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-22 11:27 -0800
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-22 19:44 +0000
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-22 19:40 +0000
                Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-23 14:13 +0000
                Re: long antenna benj <none@gmail.com> - 2015-11-23 13:00 -0500
                Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-24 13:20 +0000
                Re: long antenna benj <none@gmail.com> - 2015-11-24 13:40 -0500
                Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-25 13:44 +0000
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-23 18:47 +0000
                Re: long antenna jmfbahciv <See.above@aol.com> - 2015-11-24 13:20 +0000
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-24 19:49 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-24 16:36 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-24 23:00 +0000
                Re: long antenna gilber34 <fafa@invalid.com> - 2015-11-26 16:17 -0600
                Re: long antenna jimp@specsol.spam.sux.com - 2015-11-26 23:35 +0000
        Re: long antenna benj <none@gmail.com> - 2015-11-20 20:58 -0500
    Re: long antenna benj <none@gmail.com> - 2015-11-19 20:09 -0500
  Re: long antenna "nuny@bid.nes" <Alien8752@gmail.com> - 2015-11-24 12:51 -0800
    Re: long antenna benj <none@gmail.com> - 2015-11-25 00:01 -0500
  Re: long antenna "reber g=emc^2" <herbertglazier0@gmail.com> - 2015-11-25 15:36 -0800
    Re: long antenna jimp@specsol.spam.sux.com - 2015-11-25 23:51 +0000

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