We created a custom screen and placed a link to this screen on our company intranet. When clicking on this link, it directs the user to the custom screen, but does not prompt the user to login before getting to the screen. Without them logging in, the reporter field will not be available.
JIRA should prompt you to log in before it shows you the screen, unless you have anonymous access enabled somewhere for the project. (see http://confluence.atlassian.com/display/JIRA/Allowing+users+to+create+issues+anonymously)
Are you trying to give your users a simple form to fill out to create a JIRA issue? You could also use the JIRA Issue Collector for this purpose:
(the issue collector is included in JIRA 5.1 and above)
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