If I would set up electromagnetic emitter that would emit one wave, but while it would be emitting it I would spin emitter 180 degrees at such speed that one half of wave would be emitted in that time (or it could be 1 degree, but the speed of turn would have to match the half of wave's oscillation) and then would set up a lot of sensors on the path of the wave that are able to measure strength of electromagnetic field (so that it would hit multiple sensors with that partial wave, sensors can be placed as far away as it needs be to allow the small turn in angle allow to have bigger affect). Would all the sensors show the value of the field going up to the peak and back down to zero, or would first sensor absorb the wave and all other sensors would show 0 values.
Update: Reason I am asking is that I can't wrap my head around - for sensor to register something it has to be affected by electromagnetic field - to affect sensor some energy has to be used, if wave would affect all the sensors it would imply that it has infinite energy as increasing the amount of sensors would still 'do to the work' register a value, but there has to be more 'work' done with each additional sensor, so in my understanding 1st sensor (or some other) would have to take all the energy of the wave and rest would not get anything.
Please forgive me if question is unclear or silly, I am not a physicist. If you need additional information please ask I will do my best to clarify.