I understand that you want to test the antenna design function with a time varying function that emulates the signal of a radio station rather than just a scalar frequency. However, as per the documentation page for the design function, the frequency argument only accepts a real positive scalar. Thus, substituting the scalar with the radio station signal seems to be out of scope.
To better assist you, it would be helpful to understand your motivation behind creating a function that models a radio station signal and replacing the scalar value while using the design function. By understanding your specific requirements, I can provide more targeted guidance and suggestions to meet your needs effectively.
Have a look at below references for further understanding
I hope this helps.
