This is a link to an article stored at the LWCA website. This article is written for experimenters who use the 1750 meter band (160-190 kHz) where the Part 15 rules about power limits and antenna size are very different from the rules for the AM broadcast band. However, the antenna design principles are the same. Understand? Here's the link: Getting The Most Out Of LowFER Transmitting Antennas by Lyle E. Koehler, K0LR.