Author Topic: My dumb questions  (Read 13022 times)

0 Members and 1 Guest are viewing this topic.

Sacajawea

  • Jr. Member
  • **
  • Posts: 35
  • Karma: 9
  • Gender: Female
My dumb questions
« on: March 20, 2015, 01:53:55 PM »
OK, that didn't take long. I figure I better put these all in one place. Maybe my questions don't matter; maybe it's just my resistance to certain subject matter... sigh... but this is what stops me (right at the beginning) every time.

The books and other material tell you these things without explaining how it works; I recognize I don't know how it works -- and my brain freaks out until it solves those "mysteries".
-----------------------------------------------------------------------------------

How can a radio wave travel at the speed of light? Wouldn't it travel at the speed of sound, instead? Doesn't it stop being sound at that higher rate of speed? [you were warned about the nature of the questions...]

What makes a signal change direction in an antenna -- and how does it break out of that cycle to the open air?

ghrit

  • Prepper
  • Full Member
  • *
  • Posts: 279
  • Karma: 22
Re: My dumb questions
« Reply #1 on: March 20, 2015, 02:57:34 PM »
Sac, the only dumb question is the unasked one.

Radio waves are simply the same thing as light waves and travel at the same speed.  The only real difference is the energy contained in the photons that make up the waves.  Sound is a mechanical disturbance of the medium and is WAY slower, as well as being unable to travel in vacuum (like space.)  If they weren't different, we could not communicate with satellites in space, since there's no air to carry the sound.

So far as the antenna question goes, you can visualize it (tho' highly inaccurate) as the radio wave in the antenna has no place to go when it gets to the end, so it escapes by jumping off the side.  For now, that's the best visualization I can come up with.  As you go further into the theory, you should be able to get a grip on the reality of radiation off the antenna.
« Last Edit: March 20, 2015, 03:01:48 PM by ghrit »
There are two kinds of ships.  Submarines and targets.
KB3ZMF        FN21dy
Amateur Extra Class,  VE
www.survivalmonkey.com

AD

  • Administrator
  • Hero Member
  • *****
  • Posts: 1991
  • Karma: 223
  • Gender: Male
  • Extra Class Ham Radio Op / VE, CERT
Re: My dumb questions
« Reply #2 on: March 20, 2015, 03:00:27 PM »
SAC

You are way over thinking. 

First question
Radio waves travel at the speed of light.

You are confusing the sound out put from a radio(speaker) which travels at the speed of sound with the electromagnetic portion of the spectrum.

Light, radio waves, xrays, microwaves are all part of the same spectrum
http://www2.lbl.gov/MicroWorlds/ALSTool/EMSpec/EMSpec2.html


All of these move at the speed of light.

The same way you can feel heat from a camp fire(radiant heat) or a stove, electromagnetic waves(radio) will radiate from an antenna when conditions are right: input to the antenna by the radio and the physical/electrical properties of the antenna.  The antenna needs to be the proper configuration(length for instance) for the radio waves to radiate from it like heat from a camp fire.

Clear as mud?
The only dumb question is the one that did not get asked!!

AD

  • Administrator
  • Hero Member
  • *****
  • Posts: 1991
  • Karma: 223
  • Gender: Male
  • Extra Class Ham Radio Op / VE, CERT
Re: My dumb questions
« Reply #3 on: March 20, 2015, 04:02:34 PM »
« Last Edit: March 20, 2015, 04:11:02 PM by AD »
The only dumb question is the one that did not get asked!!

Sacajawea

  • Jr. Member
  • **
  • Posts: 35
  • Karma: 9
  • Gender: Female
Re: My dumb questions
« Reply #4 on: March 20, 2015, 06:35:20 PM »
Thanks!!
It's not so much overthinking; it's that faced with a simple scientific statement I feel I have no context to assimilate it into. (It's not true; it's conditioning - long story). I know a lot about light, transmitted vs reflected and the color spectrum.

After a couple meltdowns with that much, I went & looked at the sample questions for that chapter - yeah, the info stuck despite the hysterics - and I could pretty much answer all those. If that's the biggest hurdle - in it's preposterous-ness - I'll be OK. I think I might do better with the online materials info-presentation. But I'll the AARL book another chance.

spacecase0

  • Hero Member
  • *****
  • Posts: 790
  • Karma: 34
    • my spiritual forum
Re: My dumb questions
« Reply #5 on: March 21, 2015, 10:21:28 AM »
don't let this mess with your head to much,
but empty space has an impedance as well as your antenna
free space has an impedance that is 376.73031... ohms
http://en.wikipedia.org/wiki/Impedance_of_free_space

AD

  • Administrator
  • Hero Member
  • *****
  • Posts: 1991
  • Karma: 223
  • Gender: Male
  • Extra Class Ham Radio Op / VE, CERT
Re: My dumb questions
« Reply #6 on: March 21, 2015, 10:37:08 AM »
I can see her head exploding right about now...... :o
The only dumb question is the one that did not get asked!!

ghrit

  • Prepper
  • Full Member
  • *
  • Posts: 279
  • Karma: 22
Re: My dumb questions
« Reply #7 on: March 21, 2015, 11:36:04 AM »
I can see her head exploding right about now...... :o
Yep.  Time to dump the mains and re-energize the smaller circuits --
There are two kinds of ships.  Submarines and targets.
KB3ZMF        FN21dy
Amateur Extra Class,  VE
www.survivalmonkey.com

spacecase0

  • Hero Member
  • *****
  • Posts: 790
  • Karma: 34
    • my spiritual forum
Re: My dumb questions
« Reply #8 on: March 21, 2015, 03:00:34 PM »
I just figured that it is handy to know,
it is how I visualize the power getting out of the antenna,
on a 1/4 wave whip antenna,
the feed point is 50 ohms, the top of the antenna is about infinite ohms,
and somewhere in the middle it matches the impedance of free space,
and that is where it is super easy for the radio waves to escape,
the antenna and space are a perfect match there...

or at least that is the way I see it happening

Sacajawea

  • Jr. Member
  • **
  • Posts: 35
  • Karma: 9
  • Gender: Female
Re: My dumb questions
« Reply #9 on: March 21, 2015, 04:11:35 PM »
LOL. That is about what happens in my head, too.  ::)

AD

  • Administrator
  • Hero Member
  • *****
  • Posts: 1991
  • Karma: 223
  • Gender: Male
  • Extra Class Ham Radio Op / VE, CERT
Re: My dumb questions
« Reply #10 on: March 21, 2015, 05:10:49 PM »
Graphic designer/photographer?
The only dumb question is the one that did not get asked!!

Cindy

  • MissCommunicate
  • Jr. Member
  • **
  • Posts: 65
  • Karma: 6
  • Gender: Female
Re: My dumb questions
« Reply #11 on: March 22, 2015, 03:03:35 PM »
Thanks!!
It's not so much overthinking; it's that faced with a simple scientific statement I feel I have no context to assimilate it into. (It's not true; it's conditioning - long story). I know a lot about light, transmitted vs reflected and the color spectrum.

After a couple meltdowns with that much, I went & looked at the sample questions for that chapter - yeah, the info stuck despite the hysterics - and I could pretty much answer all those. If that's the biggest hurdle - in it's preposterous-ness - I'll be OK. I think I might do better with the online materials info-presentation. But I'll the AARL book another chance.

You go girl!   It's not that bad, I sat for Tech and General together.  You can do it.

-Cindy
Into Preparedness and Communications since 1987

W.Lynn

  • CDT
  • Full Member
  • ***
  • Posts: 306
  • Karma: 21
  • Trouble-making grandma
Re: My dumb questions
« Reply #12 on: April 02, 2015, 03:44:13 AM »
Sac, you're plenty smart enough for this, that's why you want to know these things before you move on. I bet grade school was very frustrating for you, because so many adults either won't explain things, or aren't very good at it.

Sacajawea

  • Jr. Member
  • **
  • Posts: 35
  • Karma: 9
  • Gender: Female
Re: My dumb questions
« Reply #13 on: April 17, 2015, 08:52:08 PM »
Thanks W.

AD - FINE artist to you... with an AA in Graphic Design. I do processes & systems & technique really well though. Plenty of mechanical ability, too. Plopping blobs of paint on a canvas never seemed too interesting to me... so most of my images were visual puzzles.

Sorry; life is getting in the way again. Back to the book/website!!

AD

  • Administrator
  • Hero Member
  • *****
  • Posts: 1991
  • Karma: 223
  • Gender: Male
  • Extra Class Ham Radio Op / VE, CERT
Re: My dumb questions
« Reply #14 on: April 17, 2015, 09:05:16 PM »
You know I am kidding.  We just want you operational asap. 
The only dumb question is the one that did not get asked!!