A Palmer Scan is a combination of a Primary Scan and a Secondary Scan., Slotted waveguide: Main article: <a href="http://en.wikipedia.org/wiki/Slotted_waveguide">http://en.wikipedia.org/wiki/Slotted_waveguide</a> Applied similarly to the parabolic reflector, the slotted waveguide is moved mechanically to scan and is parti