Transmission Line Transformers: Theory, Design and Applications—Part 1

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  • Author: Chris Trask
The concept of trans-mission line trans-formers (TLTs, also known as equal delay transformers) has been a distinct element of RF cir-cuit design since at least 1944, when Guanella disclosed an impedance transformer of novel design which consisted of a pair of interconnected transmission lines [1,2]. TLTs have been found to possess far wider bandwidth and much greater transmission efficiencies by arranging the windings of the TLT to have uniform transmission line proper-ties. In general, these devices are widely used for matching networks for antennas and amplifiers in the HF and VHF bands [3], and their low losses (a fraction of a dB) make them especially useful in high power circuits [4].