http://www.my.site/test.php?link[]=http://stackoverflow.com/?as=2&bs=2&link[]=http://stackoverflow.com/?af=2&bf=2

echo 'http://www.my.site/test.php?link[]=' .
      urlencode('http://stackoverflow.com/?as=2&bs=2') . '&link[]=' .
      urlencode('http://stackoverflow.com/?af=2&bf=2')