The last antennae I used was from a motor cycle. (used in the front furrin section)It was the type that had about a 3' main line and 2 ears that went out along the roof where I had my overhead console. , when I moved the radio to the dash I just mounted the ant. ears along the inside of the firewall under the dash out of site.
There is also a co. now called secretaudio that has a "hidden" ant. but my motor cycle ant. worked great
Good Luck, bowtie