FM antenna mod ?

The swirl pattern is important for reception. I don't remember why. The Mazda 3 has the same antenna, only longer, and it screws right in (I tried my neighbor's). I'm thinking of getting one to try to improve reception. It too has the swirl pattern on it.

Nate

 

The swirly pattern eliminates wind noise while traveling at freeway speeds. That's all it does. If you don't like the looks and would rather hear some wind noise, that's OK with me. The auto companies think that wind noise reduction is more important. You should notice this on every new vehicle with a mast-like antenna that does not telescope.

 

I always thought that the reason for the swirls was to make the antenna have great reception and still be flexible due to wraping extra metal along the stalk. *shrug*

 

My previous car to my Prius was a Lexus IS300 with the exact same swirly mast antenna stock as our Prius'. It sucked and looked awful. I switched it out for JDM short antenna that was not swirly and about 5 inches shorter. Honestly, the reception seemed the same to me. Not sure if that was because I had an FM diversity reception antenna printed on the rear window as well though. Honestly, I listen to XM all the time and don't care about FM reception so I'm changing my Prius antenna to a short one as well. Hoping of course that the mast isn't also the Nav system antenna...

Short antennas that fit our car are pretty much universal and will work on Mazdas, VWs, Toyotas. They can be found on eBay for about $10-$20. There are some that are made of solid aluminum that claim to get as good reception as stock, but they look a little ghetto to me.

 

:idea: If my memory serves me.....

As I recall from my father's Ham Radio days, the coil wrapped around the antenna mast causes the antenna to receive signals as if it were several times its actual length thus materially improving reception. If effect this 'coil' electronically lengthens the antenna.

Perhaps some electronic 'wizard' can comment..... tell me either I'm certified nuts or correct.

Disclaimer: That's my best guess from a less than perfect memory.

 

I was on the launch team for a GM product (I prefer to leave the name anonymous), and they initially had one of those foldable antennae's. Shortly after launch, customers complained of poor reception. They changed to a traditional one mounted on the fender. I know that the short ones look good, but they don't work as well.

While on this launch, I asked the Design Release Engineer why there were swirls. I was told that it creates less wind noise. That's were I received my information - not from some auto junkie off the street.

 

Charles...

Your memory does serve you quite correctly. It is known as helical loading with the coil going the whole length of the antenna. It is to create a effective 1/4 wave antenna in a shorter space. There is a limit how much shorter you can make the antenna before you start to significantly loose efficiency though.

But... if the shaft of the ant is already metal and that pattern is just of epoxy, then the sole purpose of it, just as Whitey said, is it's only for reducing the whistling at highway speeds.

 

as for the swirl in the antenna, its for the reception for the AM radio broadcast band...it in essences has become a "short antenna on the broadcast band, otherwise a true AM antenna would be astronomically huge...the rest of the antenna is a short 1/4 wave on FM...