 The term PIFA is reserved by many authors (e.g. Sánchez-Hernández) for the shorted patch antenna where the antenna element is wide with the ground plane underneath. The thin line type of inverted-F antennae with the ground plane to one side like A and B in the diagram are just called IFA even if they are in planar format. An author may even call an IFA of this type a printed inverted-F antenna but still reserve PIFA for the shorted patch type (e.g. Hall and Wang.)
