MFJ invented the tunable active antenna! Numerous copies have been made without success -- including most recent ones. Why? Because MFJ has made continuous improvements where others have not. The MFJ-1020C has been completely redesigned with new technology. New technology uses a dual gate MOSFET and a gigahertz bandwidth buffer. It improves gain and selectivity, reduces noise and intermod, and is NOT prone to self-oscillations that can severely damage your receiver.