23. ANGLE SHIFT – PART I
THE CHANGE OF THE SIGNAL EMISSION ANGLE
If the arrival target of a signal is a reference system that is in
motion, depending on the direction of the movement of the target, the
signal emission angle changes. I named this event “Angle Shift”.
In the figure above, when the plane is at (x1,y1,z1)
coordinates, let’s discuss a signal that the station on the ground
emits and that targets the plane as its arrival point. The signal sets
out at t1 moment when the plane is at (x1,y1,z1)
coordinates. During the travel time of the signal, the plane continues
its movement in its own direction of movement. In the end, the signal
reaches the plane at t2 moment and at (x2,y2,z2)
point.
If the plane wasn’t in motion, the same signal would reach the plane at
(x1,y1,z1) point. However, as the
plane is in motion, the signal reaches the plane at (x2,y2,z2)
point. To make it easy to think about it, let’s think of a single
photon. While the signal (photon) would normally go to (x1,y1,z1)
point, it goes to (x2,y2,z2)
point instead. For such a situation to occur, it is necessary for the
signal to change its direction during its emission, which it does
indeed; it changes its direction.
The direction change of the signal occurs in parallel with signal
wavelength change and at the moment of signal emission. The reason the
signal changes its direction is the same. Whatever reason leads to
signal wavelength change, the same reason also determines the direction
of the movement of the signal. In the figure, the angle where d1
and d3 lines intersect gives us the
amount of change in the angle of the movement of the signal relative to
the reference system of the transmitter.
It is going to be a kind of repetition, but I’m writing it again:
d3 line in the figure is the direction of the outgoing
signal relative to the reference system of the signal tower.
d1
line in the figure is the direction of the incoming signal relative to
the reference system of the plane (Remember that we assume the plane is
motionless and the signal station is in motion.).
There is no rule saying that Angle Shift occurs all the time. If the
movements of the source and target reference systems are on the same
line (if it happens on a single dimension), the signal emission angle
doesn’t change. In all cases except this, Angle Shift occurs.
We saw that wavelength change can be described based on distances.
d0 : The distance that the INCOMING signal
covers relative to the receiver
d1: The distance that the OUTGOING signal covers relative to
the transmitter
λ0 : Wavelength of the transmitter’s factory setting
λ1 : Wavelength measured at the receiver
If we pay attention, for a wavelength change to occur, the lengths of d0
and d1 distances must be different from each other; this
situation by itself shows that Angle Shift is a must.






I’ll keep discussing Angle Shift in Chapter Three.