k-Wave User Forum » Topic: what's the difference between dB/(MHz^y cm) and dB/(MHz/cm) ?

k-Wave User Forum » Topic: what's the difference between dB/(MHz^y cm) and dB/(MHz/cm) ? http://www.k-wave.org/forum/topic/whats-the-difference-between-dbmhzy-cm-and-dbmhzcm Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 09:52:08 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php wang_feng_2020 on "what's the difference between dB/(MHz^y cm) and dB/(MHz/cm) ?" http://www.k-wave.org/forum/topic/whats-the-difference-between-dbmhzy-cm-and-dbmhzcm#post-7366 Sat, 04 Apr 2020 06:17:25 +0000 wang_feng_2020 7366@http://www.k-wave.org/forum/ Thank you,Brad. Maybe they think dB/（MHz/cm） is same as dB/(MHz^y cm).Iin one paper,I find this:"The attenuation coefficient (α) varies with frequency as:α=a * f ^ b.where coefficient a has units of Np/cm/MHz, f is the frequency in MHz, and coefficient b is dimensionless. " Bradley Treeby on "what's the difference between dB/(MHz^y cm) and dB/(MHz/cm) ?" http://www.k-wave.org/forum/topic/whats-the-difference-between-dbmhzy-cm-and-dbmhzcm#post-7358 Fri, 03 Apr 2020 15:07:49 +0000 Bradley Treeby 7358@http://www.k-wave.org/forum/ Hi wang_feng_2020, That doesn't sound dimensionally correct. Maybe they listed the units wrongly? Brad. wang_feng_2020 on "what's the difference between dB/(MHz^y cm) and dB/(MHz/cm) ?" http://www.k-wave.org/forum/topic/whats-the-difference-between-dbmhzy-cm-and-dbmhzcm#post-7357 Fri, 03 Apr 2020 12:02:30 +0000 wang_feng_2020 7357@http://www.k-wave.org/forum/ thank you,Bradley. in a database,the unit of absorption is dB/（MHz/cm） and b is 1.5.(i don't know whwther b is y ) But if b is y, how do I convert units to dB/(MHz^y cm)? Bradley Treeby on "what's the difference between dB/(MHz^y cm) and dB/(MHz/cm) ?" http://www.k-wave.org/forum/topic/whats-the-difference-between-dbmhzy-cm-and-dbmhzcm#post-7348 Wed, 01 Apr 2020 15:22:18 +0000 Bradley Treeby 7348@http://www.k-wave.org/forum/ Hi wang_feng_2020, The absorption in many materials follows a frequency power law of the form a0 * f ^ y. Here a0 is in units of dB/(MHz^y cm), and f is frequency in units of MHz. If y = 1, there is a linear dependence on frequency, and the units would then be dB/(MHz cm). Brad. wang_feng_2020 on "what's the difference between dB/(MHz^y cm) and dB/(MHz/cm) ?" http://www.k-wave.org/forum/topic/whats-the-difference-between-dbmhzy-cm-and-dbmhzcm#post-7338 Tue, 31 Mar 2020 12:13:00 +0000 wang_feng_2020 7338@http://www.k-wave.org/forum/ In some paper,the unit of attenuation is dB/(MHz/cm).what's the difference between dB/(MHz^y cm) and dB/(MHz/cm) and what does y mean?