So here is the old retired aviator sitting at his computer and smiling his satisfaction at what he is reading. Thank God the FAA is still requiring the teaching of things that:
1. No one can prove.
2. Cannot be changed by the pilot.
3. Make not a particle of difference in how the pilot operates his aircraft in the regulated airspace over our heads.
4. Might very likely be out of date before the ink is dry.
The lighthouse model is workable, requires no further modification unless the real
explanation is simpler.
Your instructor's statement:
...may very well be true. In fact I'd bet a very small amount of money that it is. HOWEVER we cannot compare a thing with itself and learn anything. So if there IS
a phase difference (whatever that means) by radial, well then there must be at least two components to that one signal - and it follows that one would be, in effect, omnidirectional and the other unique to the radial. Hey! That sounds just like the lighthouse model!
As for ADF, well, I used to fly the old stuff: Sense antenna from tail to top of canopy and loop antenna somewhere out in the slipstream. The most primitive I flew had a hand-cranked loop with a small, crude compass rose on the control head to show you loop orientation reference the aircraft nose. It was easier to turn the airplane than to crank the loop. It was very easy to head the wrong direction down the line bearing you got. Better to turn 90° to it, fly a while then take another cut. They were bound to come together somewhere.
Last I heard, some years back was that a solid-state directional antenna (of the day) had a ring of paired dipole antennae and it compared signal strength between the sets of pairs to find the line bearing (TO or FROM) then used some feature in these dipoles that made them receive better in one direction than the other to resolve which was TO
At that point the needle pointed to the station and you either fly the head or the tail of the needle depending on which way you were going. It was important only to remember that you cannot move the head of the needle, you can only use aircraft heading to drag the needle tail left or right through that little fulcrum in the middle of the needle. Easier to demonstrate in the airplane than to explain in text.
Some day they are going to use accelerometers and ring-laser gyros and small computers that can sense heading and speed and track over the ground to find winds aloft and they will use air data computers to correct airspeed and altitude and... Wait a minute. That happened thirty years ago!
Well, some day they are going to launch a bunch of satellites that will tell ground stations where they are and these are going to be small enough to put in airplanes and ... Wait a minute! That happened twenty years ago.
Some day they are going to have VLF and Microwave nav systems and... No. Really, they're not going to. Those were just empire building programs by the same folks who require that a pilot who is not going to be allowed to visit a VOR understand how it works - as opposed to understanding how to work it.
Well, don't feel bad. Last I heard it is still necessary to teach aircraft dispatchers Adcock Range (Morse "A" and "N") but not necessary to teach them anything about computer-based flight planning.
Happiness is not seeing another trite Ste. Maarten photo all week long.