If the Calendar iCal module is enabled, the default Calendar view will include an iCal display that you can use to create iCal exports of your calendar.

To use the iCal export, look for the iCal display in the calendar. The default iCal feed uses a Date filter set to show events greater to or equal to 'now'. Find the date filter on the iCal display and change it to use the date(s) used in the calendar. Then attach the iCal feed to the Calendar Page and/or the Calendar Block.