3D-printed Broadband Impedance Transformers Using Helical-microstrip Transmission Line Segments.

In this article, 3D-printed helical-microstrip transmission line segments are used to implement compact broadband impedance transformers intended to work in the frequency range from few hundreds of MHz to several GHz. Two different topologies of tapered impedance transformer were designed fabricated and tested. In both cases, experimental results agree with electromagnetic simulations performed using the finite element method. The results demonstrate that the use of helical-microstrip technology allows to reduce the length of the transmission line segments by a factor of about 5 in comparison with an ideal transformer with the same minimum operating frequency.