Expanding Bandwidth with Ferrite Loaded Transmission Line Devices

Many passive multiport devices - such as power dividers/combiners, baluns, hybrids, and impedance transformers - rely on electromagnetic (EM) coupling for their intended functions. In the microwave range the coupling is typically achieved through a capacitive (electrical) interaction between closely spaced transmission lines. With this coupling mechanism the broadest available bandwidth is achieved when the length of the coupling section approaches quarter of the wavelength. Consequently as the frequency drops below the microwave range the size of devices utilizing this coupling mechanism grows prohibitively large.