Topic: The width of the horizontal beam

[Kimi]

Hi folks! Just wonder how wide/narrow the horizontal SI-beam is. And (is there a) difference betwean 455 and 800 kHz.

Kimi..

[Humminbird_Greg]

Kimi,
Are you meaning how wide the beams are left-to-right or front-to-back?

Left—right they are:
455kHz  86 degrees
800kHz  55 degrees

Front-to-back they are both 0.5 to 1.5 degrees.  I’m not sure what the exact measurement is but they are pretty thin.

[Kimi]

Thanks !

Those numbers are close enough!

Kimi

[Rickard]

Kimi,

Edgetech has a good text on beam widths here: http://www.edgetech.com/docs/app_note_beamwidth.pdf

If the approximate formula is applied to the HDSI transducer the result is 1.5 degrees at 455 kHz and 0.9 degrees at 800 kHz. As Edgetech explains, this is the one-way -3 dB measure. Actually, the practical widths are even narrower because the beam is further slimmed when the transducer receives the echo. This two-way width is 1.1 degrees at 455 kHz and 0.6 degrees at 800 kHz.

Rickard

[Kimi]

Thanks Rickhard!

Great information

Kimi...