N. Berger et Fm. Landstorfer, Optimum-shaped broadband balancing microstrip-coupler without bridges or load but with even-mode suppression, ELECTR LETT, 37(14), 2001, pp. 900-902
A major problem in microwave technology is the connection of an unbalanced
transmission line to a symmetrical (balanced) load, e.g. a dipole antenna.
A broadband solution for this problem is presented in the shape of a simple
and low-loss microstrip circuit without absorbing loads, shorts or expensi
ve air-bridges, which offers more than one octave of bandwidth and good sup
pression of the even-mode.