yes, in fact you can simulate a doppler shift with
a stepped ramp of phase. In other words between
your antenna and the device under test, if you add
a phase shifter and digitally program it to be 0,
22.5, 45...337.5, 0, 22.5...degrees, the frequency
will appear to shift. You can get the frequency
to shift upwards or downwards by the direction you
program the phase sequency. This is useful in things
like jammer systems on a military airplane, where
the pilot wants the missile coming at him to think
he is travelling at a different velocity than he
Unfortunately, since most forms
of mobile communications use phase modulation in
their detection, you are not going to be able to
use this way to simulate the doppler frequency shift.
Your communications device will try to track out
the shifts, and make all sorts of bit errors while
trying to do so.
I would take the signal
(2.45 GHz for example) use a stable frequency synthesizer
and upconvert it in a mixer to 8.45 GHz with a 6.0
Ghz local oscillator signal). I would bandpass filter
it, and then downconvert it back to the band of
interst with either a 6.0000035, or a 5.9999965
GHz LO. If you want to change the apparent doppler
shift, you just redial the frequency.
on what the communications device is you are testing,
you might have to lock the two LO synthesizers together
with a common clock frequency.