Dude all i can tell you about ADF is that dont bother wasting ur time trying to understand how to fly one. First of all, they only thing there good for is taking u to the station, doing an ADF/NDB app. these things aren't exactly accurate. Further more, this technology is well for the better lack of word, Old Technology. I agree with the other guy, start learning about GPS, its hear and its the future. I'm a pilot and I never once flown an ndb approach or adf. it helps if ur lost, thats about it but if you get lost with gps, well then somethings wrong. but seriously don't waste ur time on adfs and ndbs bro. Good luck on ur career. And one more thing, if you fly FSX, try going through the learning center, its a pretty good setup FSX has. Not sure if they even get into ADFS but they have some pretty cool training aids for the student pilot. Best of luck.