Optimum-shaped broadband balancing microstrip-coupler without bridges or load but with even-mode suppression

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 expensive air-bridges, which offers more than one octave of bandwidth and good suppression of the even-mode