The paper shows that an existing description of coupled transmission l
ines is inconsistent and proposes a new model based truly on the mutua
l coupling concept. In the existing formulation a series electric coup
ling and parallel magnetic coupling are combined. In the new formulati
on the parallel electric and magnetic couplings as well as series elec
tric and magnetic couplings are used. Obtained model of coupled lines
has physical background related to the odd and even type of propagatio
n and agrees with the practical results.