If your window has no casing but a blind, mini-blind curtain rod brackets are also a good alternative to fixed brackets. On a scale of 1 to 10, I'd give these options 9 or 10.

This no drill curtain rod from Ikea is less than $10 but packs a big punch in terms of function and convenience. Twist it to fit into your window. Ikea FJÄDRANDE Curtain Rod ...