My car doesn't have an aerial fixed to the body so I tried a powered hidden one under the dash. Unfortunately it was useless.
I recently came across a period looking wireless speaker that can play sound from your smart phone or you can insert a SD card. I've made an aluminium bracket that will hang off the bulkhead under the dash, above the transmission tunnel. It'll be about 8cm from the bulkhead, which should make the bass sound good. It'll be just about visible from the driving seat and close enough to be manually controlled by the buttons on the top. Here's a picture of it in the bracket ready to be fitted soon. I'll also fix a strut back to the bulkhead to keep it still. Anyone interested, I can supply the name of the Bluetooth speaker.