First question is if these are even articles in the sense of a structural / grammatical article -- such as the Articles of Confederation or subsections of the Constitution, or if you're just calling an article because it's like a newspaper or magazine article, Technically the article tag is NOT for the latter!
That said your use of a footer for the article with a H2 describing what (who) the information that follows is about seems almost spot on to me., but suspect in practice it would/should be a H3, since I would assume your article would have a title that would be the H2, thus the content of the footer is a subsection of the header's H2, not a sibling to it.
<!-- assumes page has H1 for site-wide unifying header -->
<article>
<header>
<h2>Article Title</h2>
<time datetime="2011-11-18T14:54:39.929">18 Nov 2011 at 2:54pm</time>
</header>
<p>
Article content here
</p>
<footer>
<h3>Author Name</h3>
<img src="images/avatar.pgn" alt="author's avatar">
<p>
More info about Author
</p>
</footer>
</article>
That's why complete markup is important, as the heading depths are determined by if they're kin or descendants. Note that if your article doesn't have a numbered heading at the start, it may in fact be gibberish / confusing to even use a header in the footer.
Note again that if this were an "article" in the sense of a newspaper or magazine "article" then it's not an "article" as in an "item or particular belonging to a set". Though if you have a lot of them in a common section, then they could be both articles and articles.