The aftermarket antenna debate

[brianguild]

Guys,

What are your thoughts regarding aftermarket AM/FM antennas for your car?

I've been doing some research on this, because I'm thinking reception in my Mazda could be better. This is especially true with the new HD Radio headunit, because when those stations "fade" they don't get static-y, they just go silent. Which can be somewhat annoying.

There are a few general schools of thought, among them:

1) Can't get better than stock antenna (regardless of it's design)
2) New style antennas are more aesthetic than functional, and are not designed to pull in the best signals, OEM or not. Newer receiver technology has meant that manufacturers can get away with cheaper antennas.

Older style metal antennas were designed optimally for FM Reception. Some things I don't understand like FM frequency wavelength, etc. meant that optimal antenna length should be approximately 31" which put ideal reception capacity squarely in the middle of the 88-108Mhz band, therefore, in theory, channels in the 98.x range would receive best, and with trailing reception at either end. The issue is that this model only applies equally if all channels are transmitting with the same power. Which is definitely not the case today.

Some people have made their own, like this guy:

The magic number for good FM reception [and it'll do fine on AM] is to cut an insulated, very small wire to 31" long. With clear Caulking or other means, tack it in horizontally along the botton of the rear window. It will be virtually invisible there. It can also be placed in some other Window; that's up to you. Then, connect this Antenna to only the center conductor of some small diameter Coaxial Cable. At the Antenna end, trim back and connect the outer ground "braid" of the Coax to nothing.

Connect both the inner conductor and the outer braid ground to a mating connector at the Antenna Input of your HU. The outer braid will do its proper job of intercepting and dumping to Vehicle Ground any noise/interference. The inner conductor will connect the homemade Antenna signal to the HU. The advantage of rear Window Antenna placement is that it's far away from Ignition and other noise. OEMs also place Antennas under the rear Bumper fascia [if it's non-metallic], and are hiding Antennas under any non-metallic location they can.

If you make the mistake of connecting the Coax outer braid ground at both ends, it will carry noise it's picked up into the HU. Terrestrial Radio reception will suffer because the outer Coax braid will become a current-carrying Conductor connected at both ends.

If you measure fixed Antennas on many older Vehicles, they're 31" long cuz that length is "tuned" for the middle of the FM Radio Band. This 31" length picks AM well too. Larger diameter Wire doesn't pick up Radio Signals any better, so choose an insulated Wire diameter the size of a small Guitar String. The insulation I'm referring to is a clear or brown, Coffee-colored coating on a bare Wire. This Wire is used for winding Transformers or Speaker Crossovers, etc..

Things like the VG Sharkfin antennas may look good, but apparently are crappy for reception. Heck, even on their website they say the VG Sharkfin is "better than a stubby". I believe that... but the thing is... if it really worked better than stock, I'd be amazed.

It would be ideal if I could get something that looked good, and received signals well, but I am starting to think that might be a pipe dream.

Any thoughts at all on this, or any good or bad experiences?

Thanks,

Bri

 

[tunersteve]

Search is your friend. It's pretty much stock, CX-7, or sharkfin for our cars.

 

[brianguild]

Search is your friend. It's pretty much stock, CX-7, or sharkfin for our cars.

Steve, no disrespect man, but any antenna can go on any car.

The question was more around if anyone has tried anything else, aside from the "plug and play" options. Or, even if anyone would weigh in on their reception comparison from other options like the VG Sharkfin. In particular, can anyone vouch for the difference between stock and VG Sharkfin on the OEM radio?

Let me ask another question... does anyone know what is the gain rating of our stock antenna for FM and AM? How about the impedance?

Everyone, look at this website for some good antennas, and multi-function antennas that combine AM/FM and GPS.

http://www.acmeantenna.com/products.asp?c_id=4

 

[tunersteve]

Steve, no disrespect man, but any antenna can go on any car.

The question was more around if anyone has tried anything else, aside from the "plug and play" options. Or, even if anyone would weigh in on their reception comparison from other options like the VG Sharkfin. In particular, can anyone vouch for the difference between stock and VG Sharkfin on the OEM radio?

Let me ask another question... does anyone know what is the gain rating of our stock antenna for FM and AM? How about the impedance?

Everyone, look at this website for some good antennas, and multi-function antennas that combine AM/FM and GPS.

http://www.acmeantenna.com/products.asp?c_id=4

I understand that antennas are more or less 'universal', I was merely mentioning the most common options.

Having used stock, CX-7, and sharkfin (currently), I can say that I see little to no difference in FM reception between each one. I have similar quality now with the sharkfin that I had with the stock 'fishing pole' antenna.

I've also tried to modify a 2nd gen 6 SAT antenna to fit ours, but that is a very involved job and doesn't really justify anything for me. I've scrapped the plans for now.

 

[brianguild]

Very interesting feedback on the reception of the Sharkfin, Steve. Thanks! Anyone else?

 

[Knox Joe]

The Sharkfin degraded my reception noticeably.

I live out in the country, and with the sharkfin I don't get nearly as good of reception as the stocker. In the city there is no loss of reception.

 

[Blendercloud]

The type you go with should depend on your surroundings.

If you live in a very naturally-dense region (trees and mountains) stick with the fishing pole. If you live in a city or a relatively naturally-flat area (i.e. cornfields) go with a sharkfin. I live in St. Louis (city) and have had great luck with the sharkfin.

There is also the opportunity to replace your windshield with one that has a built-in antenna. I've noticed pretty great reception from these. Just my $0.02

 

[tunersteve]

The type you go with should depend on your surroundings.

If you live in a very naturally-dense region (trees and mountains) stick with the fishing pole. If you live in a city or a relatively naturally-flat area (i.e. cornfields) go with a sharkfin. I live in St. Louis (city) and have had great luck with the sharkfin.

There is also the opportunity to replace your windshield with one that has a built-in antenna. I've noticed pretty great reception from these. Just my $0.02

When I went from stock to CX-7, there was no change in reception. Going from CX-7 to sharkfin, only one station has a bit of noise than before. I live in a suburb, so generally there aren't too many issues with reception.

I definitely wouldn't consider going with the antenna in the window. As much as it works for aesthetics, you'd have a hole in the roof that would need patching, you'd have to worry about wiring up, which might not be straightforward, and also, you'd be running the risk of water getting by the seals, if you're installer isn't that great.