Passing A Querystring On To Another Webpage?

When I click a radio button in a certain web page (rather than a text link), I send the user on to another page.

Further requirements gathering in this project mandates that I pass a querystring on to that page.

The querystring is already captured and parsed in the host page and assigned to javascript variables and assigned to form fields.

For reasons of consistancy in Look and Feel, I use a radio button with a label as a link to another page if the user's needs requires them to go there.

If they do go there, I need to send along that same querystring.

Here is my button click action javascript:

Code JavaScript:
<input type="radio" name="_fid_30"
onClick="window.location='webpage.html'" />

At the end of that 'webpage.html', I wish to append the querystring that already is captured in the host page's URI.

Here is the javascript wherein I've captured the querystring:

Code JavaScript:
<script language="javascript">
function getQuerystring(key, default_)
{

[Code].....

With my last variable, "QS_val", I'm attempting to capture within that variable the querystring only.

I've attempted to append this value at the end of 'webpage.html', but when I click the radio button, I arrive at the page, but there is no querystring.