The Siga scale is a heptatonic scale that can be built using the following steps between notes: ¾, 1, 1, ¾, ¾, 1, ¾.
If we use (b/2) to denote a quarter note flat (a drop by a quarter tone) and (#/2) to denote a quarter note sharp, then one example of the Siga scale would be B(b/2), C, D, E, F(#/2), G, A. This example is shown below in traditional notation (the horizontal line through b denotes a drop by a quarter note and the horizontal line through # denotes a quarter tone sharp) and in guitar tablature notation (to the extent that guitar tablature allows quarter notes).
This is an Arabic scale that uses quarter tone intervals. One way to obtain this scale is to drop the first degree and to raise the fifth degree of the Locrian scale by a quarter tone. The example above is the Locrian scale in B with B lowered by a quarter tone and F raised by a quarter tone.