I recently replaced the antenna on my car. It’s for an AM/FM broadcast-band receiver. The radio doesn't seem to be receiving as well as it used to. Is something wrong with the antenna?
A receiving antenna has to be “tuned” for the same reasons a transmitting antenna has to be tuned for minimum SWR. Somewhere on the back or side of the radio is an access hole for a small variable “trimmer” capacity. It will probably be near the antenna jack. Using an insulated screwdriver or plastic alignment tool, adjust the trimmer for best reception at the upper and lower ends of the band. There may be separate trimmers for AM and FM.