A GM VP admits those shark fin antennas suck for radio reception

[Theater of My Mind]

Stumbled across this article that was published a while ago with GM's VP of global product programs, Tim Herrick, explaining why the company still puts a whip antenna on two of its vehicles today.

“The whip antenna is the best way for us to feed the [AM / FM] radio with signal,” Herrick told GM Authority. This is apparently particularly important for GM’s pickup customers, many of whom live in the countryside and prefer AM / FM radio.

“There are rural customers who buy a lot of trucks”

The Chevy Silverado and GMC Sierra are still being made with a whip antenna for AM/FM radio, alongside a shark fin antenna for satellite reception.

"that was something where we listened to the voice of the customer and they want the ability to get a signal,” Herrick told GM Authority.

Ford does the same with its 2021 F150 pickup truck but the rest of GM's vehicles, as well as those from most if not all other manufacturers, have moved to all-in-one shark fins and short stub radio antennas. Herrick's implication is that those antennas prioritize appearance over performance for customers deemed to not care as much about AM/FM radio.

Here’s Why The Chevy Silverado And GMC Sierra Pickups Still Use A Whip Antenna

 

[Deleted User]

the "shark" antennas are good for SXM and GPS reception. The higher the frequency, the shorter the antenna


You don't need a "whip" antenna, many car makers ( Porsche, Toyota, GM, etc) have incorporated radio antennas into the glass of the car for decades. they are set up like a dipole for AM reception


the perfect 1/4 wave length for a FM antenna to listen to 100.7Mhz is about 29.5 inches and 100Mhz is the half way point between 92 and 108 Mhz

 

[Kelly A]

the "shark" antennas are good for SXM and GPS reception. The higher the frequency, the shorter the antenna

In theory that statement is correct. But if you took a modern shark fin and put it up against a conventional AM-FM whip antenna, the whip loses. The filters and amplification in the shark fin style is optimized for vehicle use.

You don't need a "whip" antenna, many car makers ( Porsche, Toyota, GM, etc) have incorporated radio antennas into the glass of the car for decades. they are set up like a dipole for AM reception

That's true. The shark fin and factory system in my wife's 2020 Volvo SUV mops the floor with the whip antenna in my Ford F350 pickup. The fin provides much better sensitivity and less multipath than a whip antenna ever has.
Unlike what radio nerds believe, the auto industry is VERY concerned about providing the best experience for their customers. Evidence of this fact is; the shark fin antennas, with a lot of active electronics inside, is much more expensive to make than a chunk of metal rod.

 

[PTBoardOp94]

I assume the decline of the automotive whip antenna is in part due to fuel economy. I have no idea how much drag a 30" rod antenna provides, but I'd bet it's measurable at interstate speeds.

 

[Kelly A]

I assume the decline of the automotive whip antenna is in part due to fuel economy. I have no idea how much drag a 30" rod antenna provides, but I'd bet it's measurable at interstate speeds.

The fin houses many antennas, filters, and amplifiers, integrated into the vehicle CAN Buss data network. That includes GPS, AM/FM, satellite radio (both types) and WiFi.
Try that with a metal rod sticking out of the fender.

 

[bulwnkl]

So, what if you put the auxiliary tech at parity (amps, filters; all of it). Then how does a fin compare to a whip (including the ones that are a spiral-wrapped mast)?

 

[Schroedingers Cat]

I knew two engineers at the Warren Tech Center who were involved in Delco radio antenna design. The car designers would come up with a new idea, and they had to chase that design to make it more efficient. That often took a few years. When John DeLorean came up with the idea for the dipole embedded in the windshield, the AM reception was horrible for a few years. It never got back to where it was in the early 1960s for AM reception with the fully extended telescoping antenna, but it got better. The shark fin on my GMC Terrain isn't that bad, but it seems like there are variations in the sensitivity based on the milieu of signals. In the coldest part of Winter, it would stop the scan near Frankenmuth on WSCR, WGN, and WBBM. With the DSP, the FM isn't bad either. It seems like they have compensated for the limitations.

 

[Radig]

I assume the decline of the automotive whip antenna is in part due to fuel economy. I have no idea how much drag a 30" rod antenna provides, but I'd bet it's measurable at interstate speeds.

Assuming, for the sake of argument, that the width of a rod antenna is 1/4", then the total area contributing to drag of a 30" rod would be 7.5 square inches. That's less than that of a normal side mounted mirror, and might equal that of some larger fin antennas.

 

[Schroedingers Cat]

Automatic car washes (and esthetics for people who don't understand antennas) were the reason for the windshield...shark fin designs.

 

[kevtronics]

I don't think anyone is using a sharkfin for AM/FM. It is strictly for satellite, cell phone, and GPS. For example, my 2018 VW Jetta uses a sharkfin for those purposes, and the rear window defroster grid for AM/FM.

I think what the GM guy is actually referring to is that since pickup trucks don't have an electric rear window defroster, they still need a whip antenna for AM/FM.

 

[Radig]

The actual car body, acting as a counterpoise, is an important part of an automotive antenna system. If the whip antenna is properly installed the system will work well.

The other important factor is the reduction of ignition and other electrical noise. Some automobile manufacturers get it right with no detectable noise on the AM band, whilst others seem not to care.