There are many misconceptions and myths about VSWR. To try to overcome some of these misconceptions and to try to provide an easy and understandable summary, Electronics Notes has developed a page describing what VSWR is and this is accompanied by an embedded video.
The page and video describe how a perfect match means that all the power is absorbed by the load, and it then goes on to show what happens when there is a mismatch. The case of the open and short circuits are used to show the extreme situations and then these are developed to show what happens with loads that are less than or greater then the characteristic impedance of the feeder.
Understanding how the reflected power gives rise to voltage and current standing waves is the key to understanding what happens when there is a high VSWR.
Watch the video:
73 Ian G3YWX