Open Sleeve Coupling
Closely proximate elements are used to create resonances on multiple frequencies, only one element is driven. Employed in verticals and beams.
James Duffey KK6MC indicates that the term "Close Coupled Resonator" was coined by Gary Breed K9AY who published an article on it in "RF Design" around 1996. It is mentioned in the "ARRL Antenna Book" 20th edition and the "Antenna Compendium" volume 5, and in earlier "Radio Amateurs Handbooks". Hy Gain had a similar antenna, and Stanford had a patent in the 50's. Force12 has a new patent for their use of it.