Balanced to Unbalanced Transformer Design

Electronics Infoline Web

4:1 balun for 160 to 10 meters

Stack two T-80-2 powdered iron toroid cores together. Use super glue, or some other means to hold the two cores together.

http://www.hard-core-dx.com/nordicdx/antenna/feed/4_1balun.html

A slot design.

http://www.ctsystemes.com/zeland/publi/pg40.pdf

http://palgong.kyungpook.ac.kr/~ysyoon/Pdf/weif_03.pdf