[texhax] \textordfeminine in plain TeX

[Maurí­cio]

Hi,

How can I get an ª in plain TeX? I know of \textordfeminine in Latex, 
and would like to get the same using just TeX. My best attempt was:

\raise 0.5ex \hbox{\underbar{a}}

but the result is really ugly...

Thanks,
Maurício