May I just warn you guys that "this" from the posted Ebay ad
"On the dashboard, rear dash panel, in the trunk, under the hood, in a door, in the headliner, in a wheel well, you can hide this antenna almost anywhere! "
Screams SCAM all over the place.
The best antenna ever made would not, and could not, work well in the trunk, under the hood, or in a wheel well.
The only thing that could work better than what we have IMO, is a full 30" FM antenna mounted in the same place as the OEM.
Sure would look dorky tho.
Amps don't work except in very selective instances.
Most amps are not tunable.
Therefore they amplify the noise along with the signal.
Amps are good when........
The signal at the antenna is sufficient, but the loss along the cable route is not acceptable.
So, let's assume you have a 0 db signal at the antenna.
This is good. Not great perhaps, but good.
Now let's further assume that the cable being used has a loss of -6 DB per 10 foot of cable. (This is poor. But the cable may have other redeeming specs..... such as being extremely flexible)
So that by the time the signal gets to the radio it measures -6 DB. Not good. Very likely static and hiss time.
If one was to place a 6Db amp (Pre amp for the purists) AT the antenna, you would then send a +6 Db signal down a wire that has a -6 DB loss and would arrive at the radio with a 0 Db signal.
Life is good.
HOWEVER. If the signal coming out of the Antenna was -20 DB (Really lousy) putting a Preamp on the antenna would just make the lousy signal louder. You cannot "reconstruct" a bad signal.
So do we have 0 Db at the antenna?
Sometimes, I am sure.
Unlike a TV antenna at your house, this antenna keeps moving.
And some stations are more powerful and/or closer than others.
Could we build a better antenna in the same physical size?
What about a windshield antenna, cut to the proper wavelength?
That might be better. At least part of the time. (When the station wasn't directly behind you)
What if nothing seems to help?
Then maybe, just maybe, the radio is a POS.