Some results on the edge-coupled microstrip section as an impedance transformer

Symmetrical edge-coupled sections have been used as octave-band microstrip d.c. blocks as well as building blocks for filters, directional couplers, impedance transformers and other important transmission-line devices. In this paper, the possibility of utilising coupled sections as parts of the input and the output impedance matching networks for transistor amplifiers operating at microwave frequencies is specifically investigated including the effects of dissipation. The experimental results agree very well with the theory and confirm that low-loss transformers can be realized.