Patent ID: 7755447

Claim:
A multilayer balun having a half-wave transmission line, a quarter-wave transmission line opposed to a first half of the half-wave transmission line, with a dielectric substance therebetween, and a quarter-wave transmission line opposed to a second half of the half-wave transmission line, with a dielectric substance therebetween, the multilayer balun comprising: a first dielectric layer having a first transmission line that constitutes the first half of the half-wave transmission line; a second dielectric layer stacked next to the first dielectric layer and having a second transmission line that constitutes the second half of the half-wave transmission line, with a dielectric substance therebetween so that, during use, the current flows in the same direction as that of the first transmission line; a conductive connection between the first transmission line and the second transmission line, with the dielectric substance therebetween, so that their currents flow in the same direction; a third dielectric layer stacked next to the first dielectric layer and having a third transmission line constituting a first quarter-wave transmission line in such a manner as to electromagnetically couple with the first transmission line, with a dielectric substance therebetween; a fourth dielectric layer stacked next to the second dielectric layer and having a fourth transmission line constituting a second quarter-wave transmission line in such a manner as to electromagnetically couple with the second transmission line, with a dielectric substance therebetween; a first grounding electrode layer stacked next to the third dielectric layer, with a dielectric substance therebetween; and a second grounding electrode layer stacked next to the fourth dielectric layer, with a dielectric substance therebetween.