How to drive 1MHz Ultrasonic Transducers
From the specification, the impedance of your transducer at resonance is equivalent to a 100-350 ohm resistor in parallel with a 1300 pf capacitor.  The reactance of the capacitor at resonance (1 MHz) is 122 ohms. Most function generators should be able to drive 3 V P-P into this load.  The attenuation in air of sound is about 1.6 db per cm so it is 16 dB at 10 cm. The specification does not give the transmitting sensitivity of the transducer, that is the intensity of sound produced per volt of drive. Thus the sound level reaching your receiving transducer cannot be calculated.  Your best bet is to perform the experiment and see what level of signal you receive. Most oscilloscopes can detect levels of 1 millivolt or even less. If you can see the signal on the oscilloscope you are done.  If you cannot you will need to provide a voltage amplifier that can amplify at 1 MHz.  There are many operational amplifiers that could do this.