Apparently, the reflected power is the same as the power generated by the amplifier (both measured by the amplifier, although I double checked with a power meter). The load, a 50 ohms ultrasonic transducer in this case, seems to be completely mismatched. HOWEVER, this problem sometimes disappear after some minutes (5-10 min) without changing anything.
I have switched all the equipment, transducers and cables (+connections). Can someone rationalize this behavior? Could it be due to the driving frequency?
Some details if necessary:
The function generator is one from Agilent which I double checked by means of an oscilloscope.
The RF amplifier is from Electronics & Innovation
- The ultrasonic power transducers are from American Piezo. The behavior described is the same for everyone of them.
Note: Obviously, my background in electronics is very limited.