Effects of metal thickness and finite substrate width on leaky waves in coupled microstrip lines

The propagation characteristics of leaky waves in thick coupled microstrip lines integrated on a substrate with infinite and finite widths are presented. Field-theoretic results, based on the full-wave mode-matching method incorporating the metal modes, show that the thickness of metal strips can convert a nonleaky bounded mode into a leaky wave. On the other hand, when the infinite substrate width is reduced to a finite value, a leaky wave may become a bounded propagation mode and additional leaky waves are found. The effects of metal thickness and finite substrate width on leaky waves are discussed.<>