Researchers at Massachusetts Institute of Technology demonstrated the concept of strongly coupled magnetic resonance (SCMR) in 2007, which was able to transfer energy at mid-range with non-radioactive and high efficiency. Consequently, this signaled a renewed research interest on Wireless Power Transmission within greater scope. Particularly, long range wireless power transmission via microwave has been under close. This paper explores the principles of Microwave Power Transmission as well as the state of art of wireless power transmission. Most existing applications examined are within the short range and mid-range scope. Therefore the long distance transmission via microwave is explored more with special attention on critical areas of concern like biological factors, interference with existent system and atmosphere. Also, the attenuation effect of microwave energy is determined for 2.45GHz and 5.8GHz frequency range using some established environmental factors.