Download file ajax form

Jake,
I've also tried this:
echo "<a href=\"www.cronistalascolonias.com.ar?nome_file=$arrayLink[$num]&dimensioni_file=$dimensioni_file&dir=$dir&Id=$arrayId[$num]\">$arrayTitolo[$num]</a>";

and then in www.cronistalascolonias.com.ar :

header("Pragma: public");
    header("Expires: 0");
    header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
    header("Cache-Control: public");
    header("Content-Type: application/txt");//tipo di applicatione
    header("Content-Description: File Transfer");//trasferimento file
    header("Content-type: Application/octet-stream");//forzare il downloadf
    header("Content-Disposition: attachment; filename=$file");
    header("Content-Description: Download PHP");
    header("Content-Length: $dimensioni_file");
    readfile($file);
Header("location: www.cronistalascolonias.com.ar");

Tegatti