Fm transmitter problems?

The static is caused by the lack of connection, or poor connection with the antenna or other wires improperly connected, or broken wires make/break with bouncing over the road. (RE Spelling - decent = acceptable; descent = moving down vs up ascent).

You might want to buy an inline fm transmitter, that directly connects to the radio's antenna, and may connect via aux (better) or connect to the phone with blue tooth. Prefer aux to headset on the phone, for more stable connection - unless you're a iphone user, which doesn't have headphone jack, and many new phones are headed that way. These can be found ranging from $30-$120, on amazon, look for the best deals, but always inline fm transmitter.

Inline will still use a specific ( usually selectable ) frequency from 88-100 MHz. One of those will be unused. The best reception is when you select a frequency that isn't in use. Many aftermarket satellite (in trunk or under seat) CD caddy installations use these for easy connection to the radio.

Your last sentence has explained the cause of the problem.

There are obviously other stations in your area operating at or close to 87.7 (for example BBC Radio 2) - buy a transmitter with a selectable broadcast frequency.