Good news that your car radio now works well. When restoring my car, I decided that I didn't like having an aerial mounted on the rear wing (spoils the lines of the car and its symmetry I thought
) so I got rid of the aerial and welded up the hole. "I know a lot about aerials" I told myself "so I can replace it with something unobtrusive". How wrong I was! I first tried using the rear window demister, Mercedes do that so if it's good enough for them it's good enough for me. Didn't work! Then I created a hidden aerial in the A-pillar molding. Worked reasonably OK until the molding was put fully back in place. Then I bought an amplified aerial that sticks to the top of the windscreen. Reasonably unobtrusive and the little red power LED gives some ambient lighting in the Gamma
Works OK as an aerial but not as good as a proper external aerial.
But if I may be a bit pedantic here, your aerial would have worked even better if you used the proper radio aerial coaxial cable with 50 ohm impedance. TV cable has a 75 ohm impedance which will degrade the signal from your aerial. 50 ohm cable is used in radio transmitter antenna connections, many measurement devices and in data communications (Ethernet). 75 ohm coaxial cable is used to carry video signals, TV antenna signals and digital audio signals.