I have a main page (actually a JSP) with an iframe inside it as;
$(".excel").click(function () {
var t = $(this).closest(".tblGrid").attr("id");
window.frames["Iframe" + t].document.location.href = pagename + "?tbl=" + t;
});
this is what i use, no jquery needed for this. in this particular scenario for each table i have with an excel export icon this forces the iframe attached to that table to load the same page with a variable in the Query String that the page looks for, and if found response writes out a stream with an excel mimetype and includes the data for that table.