Antenna length

[dqa]

The stock antenna mast from my 99.5 Golf is getting ratty. Figuring all recent VW antennas are probably interchangeable, I ordered one from Amazon for ~$30.

It turned out to be part 1J0 035 849E , listed on the VW label as "VAR.ANTENA" It also turned out to be about 2.5" longer than my stock antenna (47.5cm vs 40.5cm - if you count the screw I suppose it would be about 48 and 41).

1. Am I wrong to think that antennas should be more or less identical in length, or multiples of each other, since the best reception is at multiples of the typical wavelength?
2. What is the proper part number for my stock antenna mast?
3. Are there shorter antenna lengths (other than the stubby ones) that I should consider? What are their part numbers?

 

[cvairwerks]

AM/FM antennas strictly for the commerical broadcast bands cover such a broad bandwidth that the difference in length won't make a difference. If it were for transmitting, then it could, depending on several other factors.

Don't have any handy answers for questions 2 and 3 for you.

 

[procupine14]

Shouldn't really be an issue but if you are looking for something a bit shorter without going to the "stubby" variety then you could probably browse ECSTuning.

http://www.ecstuning.com/Volkswagen-Golf_IV--TDI/Exterior/Antennas/

That is the link for your car. I think you might like some of the offerings that they have. some of them are still a normalish style antenna but half the length. I don't think that the length is going to affect your reception much if any IIRC.

 

[danham]

While the OP is correct that antenna length is proportional to the wavelength you want to receive, cvairwerks is "more" correct when he says it won't make much difference on the FM broadcast band.

So I'll just add that the phsyical length of the whip is not the last word: if there are any loading coils concealed in the antenna (which I believe there are on all modern VW "active" amplified antennas), then the effective length of the antenna is unknown unless you know exactly what the coil is doing.

Long-winded way of saying that a "longer" whip may have the exact same effective length as the OEM "shorter" one.

-dan

 

[DaveLinger]

the stock antenna on a mk4 is really not very interchangeable with other models. mk3's use 3mm threads, mk4s use 5mm threads I believe. After that it's different entirely if I'm not mistaken.

1. I don't think this assumption is right. Generally speaking longer = better reception, but I don't think you're gonna screw it up if it's not a multiple of something. In my experience, switching to a smaller antenna made no difference to my local reception but made my "out of town" FM stations harder to get.

2. 1J0035849E
3. http://www.ecstuning.com/Volkswagen-Golf_IV--1.8T/Search/Antenna/ three pages of them, all mk4 fitment.

 

[danham]

@Dave:

"Longer = better" is a common misconception. Because FM broadcast is vertically polarized, and travels line of sight, the HIGHER your antenna is above the horizon, the better chance it has of getting hit by the signal you want. But even though that means (on a car roof) that it needs to be longer, it's the height it achieves more than the length which makes FM goodness happen.

So the (theoretical) ideal length antenna for a station at 95.1 mHz would be approx. 10.5 feet. If you put the 10.5-foot whip on a 30-foot-tall tower it will get you many more distant stations at 95.1 mHz than if you put it on the roof of your VW [grin].

-dan

 

[Powder Hound]

I just use my mp3 player now.

 

[Stealth TDI]

The height of the antenna is important. But, all things equal, a longer element has more area to "capture" a signal. And it's true that antennas are tuned by their length. But they're also tuned by loading coils either at the base or wrapped around the shaft of the whip. Yeah, I said, "shaft." Anyway, a 12" antenna is not necessarily tuned to a different frequency as an 18" antenna or a 6" antenna so long as each was designed to operate at the same designated frequency (center of FM radio band, for example). But, as Dave alluded to above, an 18" antenna tuned to 98-MHz will likely receive a weak signal better than a 6" antenna tuned to the same frequency and mounted in the same location. This, of course, assumes the antennas are all designed with similar quality. A 6" stellar antenna tuned to 98-MHz just may outperform an 18" antenna of crappy design that's tuned to 76-MHz or 120-MHz.

In short, don't be overly concerned that you have the "wrong" antenna just because of a minor length difference.

 

[GenMan]

I use the Chysler Sebring shorty for under 4 bucks new at the dealer and it works great.

 

[dqa]

I use the Chysler Sebring shorty for under 4 bucks new at the dealer and it works great.

I dropped by the Chrysler dealer today to check this out. Unfortunately, they didn't have any Sebring antennas in stock, and the part number for 2000 (MR397979) was different from the 2010 model. What year was your Sebring antenna from? Another 2000 model suggested was the Charger (68040445AA), but again the part was not in stock.

Looking in the lot, they did have a few similar antennas: the Sebring, Laredo, and Nitro had a shorter, slightly beefier antenna (5064710AA) which was not in stock. The Dodge Journey (5064688AB) had one that was quite similar to mine, but shorter. It was in stock, unfortunately the thread diameter was a bit bigger.

 

[dqa]

I just use my mp3 player now.

Same here, for the most part. Which is why I didn't want the longer antenna I received.

I used to listen to a lot of shortwave, and had a long extendable whip - the length definitely made a difference for shortwave and other AM. I still occasionally enjoy picking up the traffic and weather from New York or Chicago.

 

[dqa]

2. 1J0035849E
3. http://www.ecstuning.com/Volkswagen-Golf_IV--1.8T/Search/Antenna/ three pages of them, all mk4 fitment.

That's the part number of the longer antenna I received - unless they changed the length of that part, my stock antenna should have a different part number.
Thank you (and porcupine14) for the link. I like this one, which is 23cm long.
http://www.ecstuning.com/Volkswagen-Golf_IV--TDI/Exterior/Antennas/ES251689/

 

[jcrews]

The original was replaced by that and the current P/N for the base. You don't have a choice.

 

[kiva822]

i just replaced my stock antenna with the sebring one. AM reception (which is what I need) stills sucks. I'm going to look into the antenna base next.

I like the look of the stubby and you can't beat the price.

 

[jcrews]

You can test the booster circuit with the radio's diagnostics.

Push and hold MIX for a few seconds, then you'll see the software version. Push it again, and it cycles through a few screens. One of them is the antenna power on/off indicator. If it's off, the amplifier is faulty.

 

[dqa]

i just replaced my stock antenna with the sebring one. AM reception (which is what I need) stills sucks. I'm going to look into the antenna base next.

I like the look of the stubby and you can't beat the price.

I would be cautious about going with a shorter antenna if AM is important. My experience agrees with what most have said above about FM - antenna length doesn't matter much, and even when I unscrew the antenna for a car wash the FM doesn't suffer much outside the building. AM is a different story, and I noticed a significant improvement with length with my telescoping antenna from CCrane a few years ago. It extended from 24" to 54", but unfortunately doesn't seem to be available anymore.

 

[kiva822]

I would be cautious about going with a shorter antenna if AM is important. My experience agrees with what most have said above about FM - antenna length doesn't matter much, and even when I unscrew the antenna for a car wash the FM doesn't suffer much outside the building. AM is a different story, and I noticed a significant improvement with length with my telescoping antenna from CCrane a few years ago. It extended from 24" to 54", but unfortunately doesn't seem to be available anymore.

hmmm...well, my reception sucks both and without the longer antenna. I'll try the aforementioned diagnostics...

 

[GenMan]

I think the antenna was off a 2007 convertable. I will try to find the part number.
If your reception is poor, it is probably the base. There is a booster amp in there and is probably all corroded.