A Compact Single-Stage Wide-Band Balun: A 4:1 Wide-Band Transmission-Line Balun Based on a Combination of Two Different Ferrite Cores

This article presents the design procedure and measurement results for a 4:1 wide-band transmission-line balun based on a combination of two different ferrite cores. The balun ranked first at the Student Design Competition for "Wide-Band Baluns" that took place during the IEEE Microwave Theory and Techniques Society (MTT-S) 2017 International Microwave Symposium (IMS2017) in Honolulu, Hawaii, last May and sponsored by Technical Coordinating Committee MTT-17. Each competition team was required to bring a balun designed by the students. The team that achieved the widest measured bandwidth, from 300 kHz to 1 GHz under the competition rules, was named the winner.