An outdoore omni-directional antenna, while working better than than an indoor antenna, is not a gain type antenna, It will not deliver as much signal as a gain type antenna. They deliver about the same amount of signal as the average dipole.
In general TV antennas are a compromise for FM broadcast band performance. Many of the newer TV antennas are cut for the TV VHF high band channels (starting at 174 MHz) and TV UHF channels (starting a 470 MHz). Both of these frequency ranges are far removed from the FM broadcast band. Manufactures include FM broadcast band reception in their descriptions because these antennas will pick up FM signals, just like any piece of wire put up in the air.
An omni-directional antenna will pick up a signal, a directional antenna with 15 dB of gain will pick up a signal and a manufacturer can claim that both will receive FM broadcast band signals, but there is a big difference in the amount of signal that is delivered by each antenna.
I took a quick look at the RCA antenna on line and did not find any actual specifications for it and I found three different pictures all claiming to be this antenna.
And do not believe everything that you read about antennas on the net,
One site that I took a quick look at claims that the VT-FM10 is an
omni-directional antenna with 4 dB of gain and and a front to back ratio of 15 dB. Putting the gain figure aside for the moment, by definition an
omni-directional antenna will have a front to back ratio of
zero dB.
The Stellar Labs antenna and the TV antennas are cheap enough to give them a try. Again it is all about the amount of signal that is in the air right where you put the antenna.
Web site such as
TV Fool and
FM Fool can give general information about expected RF signal strength, station coverage area and may be of some help in selecting antennas.
I am not trying to be discouraging, I am just sharing information.