If the antenna wire of your car's radio is severed or cut, you have the ability to fix it by yourself through soldering a replacement adapter end. This Mytour article provides a guide on using a basic antenna adapter for repairing a damaged car radio antenna wire.
Steps

Gather necessary materials. Prior to commencing, ensure you have the following materials at hand:
- Antenna adapter: These adapters feature both male and female ends. You'll be removing the female end of the adapter and soldering it to the severed adapter end, allowing connection to the male end of the cable (or vice versa). You can acquire an antenna adapter from electronics stores such as Best Buy or Radio Shack.
- Soldering gun or iron
- Razor blade
- Electrical tape or heat shrink
- Zip ties

Power down the vehicle and disconnect the battery. This action prevents electrical current from flowing through any of your car's wiring.

Use a razor blade to cut off the female end of the antenna adapter. Ensure you leave sufficient cable length (several inches) at the adapter head for soldering it to the severed section of the antenna wire.
- Depending on your situation, you might need to cut off and attach the male end instead. It's also possible that both ends are required—you can then attach them to either side of the severed wire and connect them together.

Remove the shielding from the end of the antenna adapter. Carefully peel away the shielding from the cut end of the antenna adapter to expose the thin metal wire inside. Make sure to remove both the black shielding and the inner plastic shielding.
- The wire at the center is delicate, so avoid cutting it.
- Expose about an inch of wire.

Peel away the shielding from the end of the broken antenna wire. Similar to the process for the antenna adapter end, uncover about an inch of wire at the broken antenna wire's end by gently removing its shielding.

Twist the inner wires of both ends and solder them together. Simply wrap the exposed inner wire from the antenna adapter around the exposed inner wire of the broken antenna. After wrapping, solder them together to form a secure connection.

Enclose the soldered connection with the pulled-back shielding. The objective is to shield the soldered wires from the heatproof tape that will be applied.

Secure the connection with tape. A single layer of tape is sufficient for now, as additional layers will be added later.

Position a zip tie lengthwise along the soldered area and tape it in place. The zip tie acts as a brace for the soldered area, providing further protection for the delicate wire inside. Wrap the electrical tape or heat shrink tightly around the connection and zip tie.
- Optionally, you can wrap additional speaker wire (if available) around the entire new connection to increase wire thickness. If you choose this option, wrap the ends of the extra wire around any exposed wire ends on either side of the connection.

Cover the entire connection with tape or heat shrink. Smooth down any protruding wires before wrapping the entire area to ensure everything is securely covered.
- If the connector is too large for the heat shrink tubing, use electrical tape instead.

Secure both ends of the tape with a zip tie. This prevents the tape from shifting and exposing any internal wires.
- If you need to attach a new male end to the other side of the severed wire, follow the same process.

Insert the male end into the female end. With a new adapter end soldered onto the severed wire, connecting the two connectors will establish a reliable antenna connection.
- Remember to reconnect your car battery before testing your newly repaired antenna wire!