The "prince of the power of the air" is Satan, ruling a vast multitude of fallen angels, "spiritual wickedness in high places" that is, 'heavenly places', opposing God and His people (Ephesians 6:12).

Source:

KJV Defenders Study Bible, by Dr. Henry Morris, Ph.D.
Publisher: Thomas Nelson
Language: English
DEF 10 ISBN 0-529-10444-x
DEF 10-1 ISBN 0-529-10445-8