If referring to width:
* Narrow
* Thin
* Slender
* Tight
If referring to scope or range:
* Narrow
* Limited
* Specific
* Restricted
If referring to general, non-specific:
* Specific
* Detailed
* Precise
* Exact
If referring to tolerant or open-minded:
* Intolerant
* Narrow-minded
* Bigoted
* Prejudiced
The best opposite word will depend on the specific meaning of "broad" in the sentence.