Khondkar Siddique-e-Rabbani (Bengali: খন্দকার সিদ্দিক-ই-রাব্বানী; born 9 May 1950) is a Bangladeshi Biomedical physicist and notable for developing the Focused Impedance Measurement method.

[3] Rabbani is the founding chairperson of the Department of Biomedical Physics and Technology (BMPT) at the University of Dhaka.

[2][4] In 2008, he became the first Chairperson of the post-graduate Department of Biomedical Physics and Technology at the University of Dhaka.

[5] Rabbani has been working to improve the condition of economically deprived people of Bangladesh through innovating low cost and easily accessible technologies.

He had three major innovations cited by Bangladesh Academy of Sciences as, "A simple and low cost method to destroy diarrhoeal germs in water using solar radiation; Surface water free of Arsenic that can be made drinkable; a localised electrical impedance technique named ‘Focused Impedance Method (FIM), having the potential to study, diagnose or characterize medical conditions including lung, stomach and vascular functions and some cancers; a nerve conduction measurement technique ‘Distribution of F-latency, (DFL), that can give inner profile of conduction velocity of motor nerve fibres in a nerve trunk, for which no clinically suitable method existed before".