If you want to use $.getJSON() you can add the following before the call :
$.ajaxSetup({
scriptCharset: "utf-8",
contentType: "application/json; charset=utf-8"
});
You can use the charset you want instead of utf-8.
The options are explained here.
contentType : When sending data to the server, use this content-type. Default is application/x-www-form-urlencoded, which is fine for most cases.
scriptCharset : Only for requests with jsonp or script dataType and GET type. Forces the request to be interpreted as a certain charset. Only needed for charset differences between the remote and local content.
You may need one or both …