ultrasound receiver
I don't have clear a question, ultrasonics like you said are in the range of 44KHz, so a 5MHz signal it's not this kind.
If you want to receive 5MHz signals first you need to use a transductor for this signals. So you will need an antenna, you can make a dipole yourself, it's easy. then you would need to use resonant circuit to get 5MHz signals. Like are low Freq signals, you can, attach anntena directly to your OA.(but remenber to keep cable distance between antenna an OA as low as possible to minimize losses and reflections, keep input impedance of OA equal to impedance od antenna (usually 50 ohms), then make an OA configuration than include a 5MHz band pass filter centered at this freq. Amplifie this signal with another OA (most commonly OA's have freq range up to 10Mhz, but you have to limite gain). and finally you have your signal
regards