Hi, my name is Luís.
I have a Magnetic Field Frequency: 73 kHz pulsing AC field. Magnetic field pulses occur approx. 3% of the time.
Do you have any sensors that can be used?
The beast method of sensing depends on a couple of details that you have not provided.
How strong is the field?
A field with strength in the range of ceramic permanent magnets or higher can be detected with just a small coil of magnet wire. Hooking up a coil to a low range AC voltmeter or oscilloscope and moving it in and out of the field is a good simple experiment to do.
Do you only need to detect the presence of the field, or do you need to determine the filed strength and/or frequency?
Again, presence detection may be as simple as using a tiny pickup coil.
Just saw your other post on this topic. You can ignore this post.