My old (2001) Seville had a cell phone with antenna mounted on the rear glass. The coax connects inside the glass, with signal passing through the glass to the whip mounting plate.
I'm wondering if I can use the old cell antenna mount (through glass) and just replace the whip to make a dual band 70cm/2m antenna. I discovered that the old cell radios in this car were on 800-850MHz, which would make a full wavelength antenna 0.35m long. Which is approx 1/2 wavelength for 440MHz, and <1/4 wave for 140Mhz
Has anyone done this before? The base inside the glass is more than a piece of metal I suspect, perhaps a loading coil. Any advice is appreciated.