as far as i know, if you are single male (living alone here in qatar) you can only sponsor your parents & brother, sister, you can not sponsor her even your salary bracket is qualified. and vise versa, if you are a single female, you can not sponsor you brother...

this fact is 1 year ago when i tried to bring here my sister... i dont know the policy now, you know, qatar immigration always changing their policies..

much better, for an exact and credible answer make an inquiry direct to the immigration.