bodyputtyless

My store bought shorty "works" when receiving those mega watt stations that play Free Bird at least twice a day. However, it doesn't work as well as the stock antenna or the stock antenna on my F150 for picking up smaller independent stations. The way i look at it is, if Ford could save money by installing a shorty antenna that "worked" as well as the long antenna they would do it. Do I love the look of the shorty? Oh yes. Do I sacrifice reception? You bet. So thats why I dropped another $125 to buy the gizmo that allows you to use your Ipod through the controls of the Shaker 500.
Life is full of compromises.

Sprzout

Maybe I'll do a shorty antenna sometime soon myself...I rarely, if ever, use the regular radio. 99.9% of the time I'm listening to XM, where the radio antenna'sgot the footprint of about a quarter.

Jens07stang

The stock antenna is around 33 inches. Seams rather random doesn't it?

GrabberOrange07

Crap, all I did is shorten my antenna to make it look cool. Now I'll have to drive at a certain speed so the radio wavescoagulate correctly over my car and interact with my audio system correctly.

Feng Houzi

thanks for the info... i cut mine last night... everyone NEEDS a dremel... i have yet to find a purpose that tool isnt made for... Anyways.. my antenna is now 13 3/4 or so... looks really good... matches the roofline perfectly... as far as reception, I wouldn't know... ive never listened to the radio here... But it looks better, and thats all that matters

Feng Houzi

fyi... it would be propagate... not coagulate... radio waves dont thicken into scabs...

wthalliii

Whether a radio signal is AM or FM has nothing to do with the wavelength. It's the frequency that determines that. The AM broadcast band is from 520-1610 KHz (0.520 - 1.610 MHz). CB is from 27,215-27,405 KHz (27.215-27.405 MHz). The FM broadcast band is from 87,800-108,000 KHz. (87.8-108 MHz).

There are many ways of designing antennas, but a vertical antenna like the one on a car is usually based on a length that is equal to 1/2 or 1/4 of the wavelength. Now, this length is an ELECTRICAL length, which may or not be equal to the physical length. The coil in effect takes the place of some electrical length. And, BTW, the wire that is spiralled around the antenna of modern cars is a coil.

Ham radio operators use a simplified formula to calculate the length of a dipole, which is 1/2 wavelength long. The formula is length = 468 divided by the frequency in MHz. Using this formula and multiplying by 2 to gett a full wavelength, we find that the center of the AM broadcast band (1.065 MHz) has a wavelength of 878 feet! So how does that dinky little antenna work? Not very well, actually. But it just so happens that the AM band is a relatively low frequency where the antenna length is not as critical as, say, the FM band, and also the broadcasters pump lots of power into their signal. Really, the car antenna is designed for the FM band. It has a much higher frequency, and the length of the antenna is more critical.

A vertical antenna like on a car is usually 1/4 wavelength or 1/2 wavelength. 1/4 wavelength for the center of the FM band is 468 / 98.4 = about 2.375 feet or 28.5 inches. 1/2 wave would be twice that, or about 4.75 feet or 57 inches. [Someone mentioned 4'9" as being an optimal length for an FM antenna - that's how this was calculated.] Now the antennas on our Mustangs are 2.75' or 33 inches long. Why is that not equal to 1/2 wave or 1/4 wave? That's where the spiralled wire comes in. It's a coil. Or look at it another way. If you unwound it, it would be longer. (Also the fact that it's wound affects the electrical length.)

My guess is that our antennas are electrically 1/2 wave. I won't get into the calculation of the effect of a coil on an antenna, but if I were going to try to shorten my antenna, I'd try cutting it exactly in half. This is based on the assumption that the wire that's wrapped around the antenna is the actual antenna. I think the thing it's wrapped around may be fiberglass or some such. I haven't cut into my antenna to find out, though. Someone who has cut his can verify this. If it is metal, then the wire wrapped around it combines with it to form a coil. Either way, I'd try cutting it exactly in half.

So why does it work if you don't cut it exactly in half? Well, antennas are not an exact thing. They work best if they're electrically 1/4 or 1/2 wavelength long, but this doesn't mean they won't work if they're not. As someone pointed out, you may be close enough to your radio station that it doesn't matter. If you're sitting next door to their transmitting antenna, you could probably use a paper clip!

Here's a couple of articles on how to cut an antenna:
http://www.mustangworld.com/ourpics/fcar/antenna1.htm
[Dang it, they're filtering the name of that site. Instead of the asterisks, try m u s t a n g w o r l d . c o m, but without the spaces.]
http://www.focushacks.com/index.php?modid=76

p51mstg

Thanks, Bill - I was hoping to see info from somebody who actually understood the subject. After I opened my big mouth, I realized how little I knew about it.

GrabberOrange - don't forget to hold out your right hand at a 45 degree angle with your fingers spread apart for best reception!

truckstoy

did that to mine a couple of weeks ago, i didn't notice any diffrence in fm reception. but hardly listen to fm mostly sirius or cd's

GrabberOrange07

Feng, they will need to scab now that my antenna is to short .

p51mstg, I actually was gonna try holding my wifes hand while she stuck her foot out the window with her big toe wrapped around the antenna.