Math & Science ⇒ Angle symbol for complex polar notation

[stefanfuglsang]

I need a extendible version of \angle{}, such that the horizontal line underlines the entire angle, like this:
A/angle

I have tried the very primitive \def\myangle#1{{\Large/\!\!\!\underline{\;\;#1}}}, but it is not very good, and it breaks appart for letters like g or y.

Any suggestions are very welcome!