PHP生成RSS XML – 编码错误

This page contains the following errors:

error on line 23 at column 14: Encoding error
Below is a rendering of the page up to the first error.

(见此处：http://aviatex14.co.uk/rss.xml)

这是生成它的代码：

while ($line = mysql_fetch_array($result)) {
  $return[] = $line;
  var_dump(date("Y-m-d H:i:s",$line['timestamp']));
}

$now = date("D,d M Y H:i:s T");

$output = "<?xml version="1.0" encoding="UTF-16" ?>
             <rss version="2.0">
                <channel>
                  <title></title>
                  <link></link>
                  <description></description>
                  <pubDate></pubDate>
                  <language>en-us</language>

                  <lastBuildDate>$now</lastBuildDate>
          ";

foreach ($return as $line) {
  $output .= "<item><title>".htmlentities($line['title'])."</title>
                <link>http://blog.aviatex14.co.uk/permalink.php?uid=".htmlentities($line['uid'])."</link>     
                <description>".htmlentities(strip_tags($line['entry']))."</description>
                <pubDate>".$date = date("Y-m-d H:i:s T",$line['timestamp'])."</pubDate> 
              </item>";
}
$output .= "</channel></rss>";
print "Content-Type: application/rss+xml";
echo $output;

$f = fopen("rss.xml","w"); 
fwrite($f,$output); 
fclose($f);

任何帮助,将不胜感激！ ：d