[RFI] Radar Engineers Model 251 Parabolic dimensions?

[Charlie Delta]

Hi Mike
I have studied the various datasheets for Ultrasonic receivers. Most have a broad beam width that is something like more than 60 degrees. This includes the widely used Kobitone transducer. I have check many datasheets including those from Murata, Monacor, Kobitone and those from many expensive USA made sonar transducers. All seem to have similar sensitivity figures all the Kobitone transducer appears to be 6db more sensitive. I just assumed that the perfect FD ratio with the perfect parabolic shape  when combined with the broad beam-width would be sufficient to flood the transducer.
I will be using a laser beam and LED endoscope light source and I will test  all of the variables as I have some  time.
I have also been informed that the Radar Engineers unit uses the 25khz frequency rather than the 40khz frequency. This apparently makes a big different in the usable   detection range. So the assumption that 40khz would produce similar results to the RE unit is clearly incorrect since the lower detection frequency would have a propagation distance advantage.
73CraigVK3OD
"One aspect of the design that may be
overlooked is the beamwidth of the
ultrasound transducer itself.  Even
with a proper F/D ratio, the transducer
may not fully illuminate the reflector
or instead spill over the edge, both reducing
gain.  The transducer's sensitivity is
another obvious factor.  Getting the perfect
reflector geometry won't mean much if
it's not matched to the transducer beamwidth.

Mike, K8CN