Radios

[noz92]

Why do radio companies spend so much money on antennas for there products, when they can simply use the protective layer around the radio instead? Or, (car radios) to get the best quality, use the exoskeleton of the car as an antenna.

 

I'm positive this will work because I've done similar experiments with a television (that had no antenna)(same basic concept). I found that I can use anything as an antenna (or almost anything). I even used my finger as an entenna and it gave just as clear of a picture and sound as the classic metal rod.

[swansont]

Why do radio companies spend so much money on antennas for there products' date=' when they can simply use the protective layer around the radio instead? Or, (car radios) to get the best quality, use the exoskeleton of the car as an antenna.

 

I'm positive this will work because I've done similar experiments with a television (that had no antenna)(same basic concept). I found that I can use anything as an antenna (or almost anything). I even used my finger as an entenna and it gave just as clear of a picture and sound as the classic metal rod.[/quote']

 

That might work for a strong signal, but for a weak signal you want to maximize the coupling efficiency in order to hear/see anything.

[noz92]

Well what would a rod antenna do that a car shaped antenna can't (the car ones bigger)?

[jsatan]

its a bit of a long story, but the signal can cancle its self out by traveling down the 'antenna' and back.

 

like sound and light and much any other wave.

[drz]

I think a replacement antenna is going for about 10 or 15 bucks, not a whole lot of money.

 

Now, there are various types of antenna's as well. I've seen some that are built into the windshield.

 

The problem with using the body of the car for an antenna is that you will get alot of electrical noise from the alternator, a whining noise that increases with engine rpm.

 

but you are correct, you can use pretty much anything for an antenna. I've made my own antenna before, using speaker wire spliced into a standard antenna, hid the wire, and got excellent reception.

[noz92]

I see.

[YT2095]

encapsulating a radio in a conductive sheild for use as an antenna is counter productive.

 

MW AM rod types won`t work under such sheilding. FM HF or VHF freqs are quite polar and so that also would be ineffective.

and as will ALL sig or energy types, a distant or opposing polarity is required, in this instance a Ground Plane, you`de be denying your radio that!

[noz92]

Now about radio chanals and stations:

 

Why is it that universally, ch.100A.M. seems to always be a long beeping tune. Toys that use radios (you know, to broadcast your voice on the radio) seem to take advantage of that by tuning themselves to that broadcasting chanel. But we've had A.M. 100 for longer then we've had the technology (or money that the average person is willing to spend on a child), so why is it done that way?

[noz92]

I've also noticed that if I take a walkie-talkie and tune to ch.1, radios I have that are able to tune to that low of a frequency don't pick up that signal. Why is this?

[YT2095]

are you on about AM or FM, as the only mics I`ve seen are FM for use in "talking on a hi-fi radio) usualy for kareoke type things.

 

walkie talkies under FCC regs are 49mhz or 27mhz as a general rule (even baby minder listening devices work on the 49 band)

 

without clarification, I can`t even hope to give a qualified answer for you #

 

 

rem also that Ch100 doesn`t mean diddly here

[Douglas]

I've also noticed that if I take a walkie-talkie and tune to ch.1, radios I have that are able to tune to that low of a frequency don't pick up that signal. Why is this?

A good antenna is a half wave dipole, but they get rather long at the lower frequencies like AM. The AM band covers more than an octave of bandwidth, so the antenna needs to be de Q'd to be able to cover the whole band, this is done by winding the antenna on a ferrite rod and perhaps loading it to De Q it.

the FM band on the other hand is much less than an octave, but yet has a center frequency somewhere in the band, thus, the reception can be worse at the band edges.

Other considerations is the polarization of the wave, I.E. vertically or horizontally polarized.

As for the car skin idea, think of the axel's, frame, drive shaft, tie rods etc short circuiting the skin, it would look like a matrix.

[YT2095]

the FM band on the other hand is much less than an octave' date=' but yet has a center frequency somewhere in the band, thus, the reception can be worse at the band edges.

Other considerations is the polarization of the wave, I.E. vertically or horizontally polarized.

[/quote']

Wow some of that brings back memories!

spending hours in the freezing cold up a ladder trying to SWR in a twig, for some guy that thought he could use his ordinary CD dipole on his new set that 10 blocks of 40ch

 

ch40 Block 5 and ch1 Block 6 SWR 1:1, and well in the red at the other ends. we gave up in the end and told him to buy a Matcher or a better twig )

 

Horizontals Great for DXing, We used to use PDL 29, only prob was we didn`t have a rotator and had to turn it manualy. The Good Old days