Antenna Picking Up Engine/Alternator Noise

I didn't notice this problem when I had my stock stereo system in (of course, the RAV had terrible speakers stock, so I probably couldn't hear it if it was there). Since I've upgraded the head unit (Alpine CDA-9815) and the front speakers (Polk components), I've noticed alternator whine in the passenger side front speakers.

I've eliminated the following sources of noise:
- Problem existed before any other components were hooked up (no rca's, amps, etc)
- Problem only in front passenger speakers
- Only exists when the engine is on; frequency/volume matches car's RPMs
- Still existed when I bypassed the stereo harness and hooked up speakers directly to head unit harness
- Remained when grounds were checked, moved and rechecked
- Does not exist when the antenna cord is unplugged from the head unit

I've read that these symptoms point to the hood transmitting engine noise to the antenna. Common solutions would be new spark plugs/wires, clean distributor cap, and a variety of fixes for a car that isn't *FIVE WEEKS* old. So I'm not sure what the answer is on this problem. Would the Big 3 upgrade help? I don't know, I guess I'm asking if you have any ideas. I've never had problems with noise on an install before, so I'm trying all the basics, but they aren't solving the problem.

I've also seen that grounding the hood to the firewall (with a copper braided wire) may help. That, the big 3, and possibly a noise filter are what I'm thinking of trying next. Not sure that a noise filter will make a difference if the problem is obviously connected to the antenna.

If you've got any ideas, I'm more than open to suggestions.