Why did Germany postpone its invasion of Britain ?

Hitler was uneasy about the consequences of a cross-channel invasion of Britain, something that had not been done successfully since William of Normandy did it in 1066.  The blitzkrieg was more designed for the open spaces of Poland and France than the probable urban fighting of London that an invasion would ultimately require.  He allowed his Air Commander Goering to try to force Britain to capitulate due to bombing, but Britain stubbornly held out--the Battle of Britain was a propaganda victory for Britain as it brought them more American sympathy and demonstrated that Britain could withstand German attack.  The Luftwaffe also lost experienced pilots over Britain.  Hitler did not have the patience to invade Britain, as in the summer of 1941 he turned his attention to invading the Soviet Union, which he looked at as the ultimate prize in the war, as the Soviet land could be used to feed the German state and provide estates for loyal Nazis.