In this paper design and simulation of Ku band 105W highly efficient GaN HEMT power amplifier is presented. A single stage design using 20 mm bare die packaged GaN HEMT device is discussed. Inductor based equivalent bondwire array model is used for this design. Simulated performance of power amplifier (PA) shows 105W output power with drain efficiency of 70% and power added efficiency (PAE) of 59% at design frequency of 11.09 GHz. Less than 0.5 dB variation in large signal gain is observed between 10.02-11.17 GHz band of frequency. Proposed GaN HEMT power amplifier can be used to repalce conventional travelling wave tube amplifiers (TWTAs) used in Ku-band satellite communication. © 2018 Association for Computing Machinery.