Im a studying ultrasonic transducer and I got a question about FWHM and Beam Width while solving some problems.
In the lecture, I learned that Beam width is calculated by:
$2\Delta\theta = \frac{3.8\lambda}{\pi L}$
where $\lambda$ is wavelength defined by $c/f$ and $L$ is a diameter of the transducer.
However, Im confused with FWHM. I thought that FWHM and Beam width are the same. But, Following the formula dose not compute right values.
I cannot find any explanations about relationship between FWHM and Beamwidth.
Some words like -3dB width, angular resolution are seen, but I couldn't get any clear result.
