Review: CravenSpeed Stubby replacement antenna

[DJ BFG]

There you go again Frogman stiring up the pot! That is awesome man, the world needs more people like you in it................ LOL

 

[Falcon]

Cool so then why does your antenna work so good being so short? that is all i am hearing about on this forum and that is what motivated me in the first place. I still can't wait to put it on my Truck.

Antennas merely pick up variations in the earth's magnetic field DJ. Some of those variations represent intelligence... man has found a way to manipulate/encode the electromagnetic spectrum of the earth to transmit that intelligence.

Radio is "old school" ... hence Kellens correct (but oh so cold <G>) observation that "Radio is Dead" ... it has been superseded by digital communications. The digital world and Pulse-Coded Modulation and Multiplexing is a whole 'nuther story.

But radio is pretty basic... two flavors: AM or Amplitude Modulation and FM or Frequency Modulation. Both merely make use of an existing medium (the electromagnetic field that permeates our planet) to encode intelligence on one end (the Transmitter) - transmit it over distance via the earth's electromagnetic field - and to decode that intelligence on the other (the Receiver).

Are you familiar with a sine wave?

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It represents that Amplitude variation I referred to. (Starting from the left) From zero volts (for sake of conversation... actually the base can be any voltage... we are only concerned about the delta - or change - from that reference) where the wave starts on the left... to the peak positive ... say 5 volts... back down to reference... past reference to the max negative value ... say - 5 volts ... back up to reference or zero volts.

That is one complete cycle... if you complete it in one second, it is called 1 Hertz. Named after Heinrich Hertz... (a brilliant man worth reading up on) it is the basis for the unit of measurement in radio. Kilohertz is 1,000 of these cycles per second, or "17 hundred (1,700) on your radio dial" Which is where you will find the AM band, and Megahertz which is one Million cycles each second. "95 MHZ" is in the FM band... the carrier for its signal is cycling (or Oscillating) 95 million times each second.

If you study on this diagram, you will notice that they started measuring time (t) from the positive peak. Makes no difference where you start, for our purposes... one complete cycle (Period T) is one complete cycle no matter where you start.

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You can also note the formula "Frequency equals the reciprocal of the period of one cycle" on the diagram. That formula is the basis of the one Kellen used of Wavelength (in feet) = 984 / frequency (in megahertz).

This wave is the "Carrier" wave - it's going to carry what information we impress upon it. From there, you either vary (Modulate) the Amplitude of the signal or you vary the Frequency slightly ... driven by and a mirror image of the intelligence you are wanting to impress upon that carrier wave.

What the fellas are talking about uses a "trick" of the electromagnetic spectrum called "Harmonic Resonance". Essentially, harmonics are mathematical integers of a given frequency. Every moving object generates them... we probably notice them most with our sense of hearing. Each sound you hear is not just one frequency... it is the sum of the basic, strongest in amplitude "fundamental" frequency PLUS the sum of all the mathematical integers of that fundamental frequency. Those "Other" phonic vibrations are much smaller than the fundamental... but the ones that are mathematical doubles, quadruples, etc. are important to us in this conversation.

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Now is the time to ask "How does the receiver 'snatch' the signal out of the air? First, remember it isn't air to the transmitter... it is an electomagnetic field. As the transmitter varies the field on its end, placing intelligence into the ether in the form of pulsating electromatic energy... the receiver is 'feeling' that field pulsate with its antenna.

Electromagnetic Induction is the phenomenon where an electromagnetic field "Induces" an electric current into a conductor by passing thru it. The key here is movement. The field moves thru the conductor, in this case our receiver antenna... and the induced voltage/current is pulsating in exactly the same manner as the field fluctuation... which, remember... was caused by our transmitter and relates to the intelligence we placed on the carrier signal.

A perfect antenna would be exactly one wavelength, or cycle.. like Kellen mentioned:

"...So if you are listening to channel 98.4 fm then the ideal length of antenna is 10 feet. Since that is crazy long, you can use fractions of that wavelength to capture the frequency pretty well. I think the 1/8 wavelength for that would be 15in. I guess our Stubby antenna would be more like 1/32 wavelength for a middle of the road FM station like that."

To put it another way, you are using harmonic wavelengths to capture the intelligence placed on the fundamental frequency. Same info... just smaller signal. Something Kellen didn't mention is that these are "Ground Plane" antennas... meaning that they are using your Raptor as part of their antenna length. The actual math is beyond me at this point (I used to do it on a slide rule... that should give you a hint <G>) but it definitely has an effect on the optimum wavelength of your receiving antenna.

Anyone still here? <G> That is why the antennas can be so short... they are working off Harmonic wavelengths as well as using the Raptor for a groundplane. Simple concept... a little hard to describe.

Falcon

 

[MarkT]

Thanks Falcon... nice post!

 

[MarkT]

I think I'm going to order one...now that Dr. Laura is on sirius I don't worry about AM reception as much. maybe it will add a few mpg's???

Dr. Laura???



(I prefer Rosie or Oprah... ) :mrgreen::mrgreen::mrgreen:

 

[DJ BFG]

uuuuuuuuuuuhhhh!!!!!!!! ok man understand lol. got it great information and post , it was very informative and useful.

 

[MagicMtnDan]

Are you familiar with a sine wave?

I know what a Sign Wave is...

 

[Falcon]

Hey, I am used to making things work when they are short.

Just ask my wife <G>.


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Falcon (& Mrs Falcon)

 

[Raptor1]

Falcon,I said it once I will say it twice. Mrs Falcon is HOT.!

 

[Falcon]

Falcon,I said it once I will say it twice. Mrs Falcon is HOT.!

She is a sweet and funny as she is good looking <G>. I OBVIOUSLY don't deserve her, but I ain't givin her up for nothin! LOL.

View attachment 295

 

[Raptor1]

She is a sweet and funny as she is good looking <G>. I OBVIOUSLY don't deserve her, but I ain't givin her up for nothin! LOL.

Great attitude! I am the same way,I look at my wife and wonder what she was thinking!