TABLE OF CONTENTS Chapter 1 established a foundation for understanding the theory and design principles of the transmission line transformer. The chapter reviewed the work of Guanella and Ruthroff and presented a comparison of their techniques for obtaining a broad-band transformer with a 1:4 impedance transformation ratio. As was noted, Guanella summed the in-phase voltages of two basic building blocks. Ruthroff summed a direct voltage with a delayed voltage from a basic building block connected as a "boot-strap" for his unun (unbalanced-to-unbalanced transformer). For his balun, he summed a direct voltage with a delayed voltage from a basic building block connected as a phase inverter.
This chapter presents analyses for the low-frequency responses of their transformers. As will be shown, the low-frequency response of the Guanella transformer (which is basically a balun) is highly dependent upon where the ground connections are made. This chapter also presents experimental data on various core materials and geometries and, in particular, treats the topic of the rod v the toroid.
Fig 2-1 shows the low-frequency models for the two Ruthroff 1:4 transformers. Fig 2-1A is the schematic for his 1:4 unun and Fig 2-1B for his 1:4 balun. These models represent the cases when the longitudinal reactances of the coiled transmission lines are insufficient and energy is no longer transmitted by a transmission line mode. Fig 2-1A can be recognized as the schematic of a 1:4 autotransformer. Although the analysis presented here is for the 1:4...
