I think tthe book of Elliott (Prentice Hall) describe some theoretical
things on slot antennas (waveguide)
or Microstrip Slot antennas: Gupta, Pozar (IEEE papers in a book)
or links in internet, for example **broken link removed**
All of the old classics like Kraus have this topic. It is the magnetic dual of a conducting dipole. You feed it across the slot in the center. This method was used in a VHF broadcasting antenna with slots in a cylinder. It also was popular in the early days of supersonic aircraft.