pifa with doable party

摘要

An antenna structure ( 126 ) that includes a Planar Inverted-F Antenna (PIFA) ( 104 ) and an extendable portion such as a whip element ( 106 ). The PIFA ( 104 ) operates normally when the extendable portion ( 106 ) is retracted and upon extension, an electrical contact is made between the extendable portion ( 106 ) and the end ( 122 ) of the PIFA ( 104 ) that is electrically opposite, i.e., furthest along the electrically conductive path of the PIFA, from the feed structure ( 202, 208 ) for the PIFA ( 104 ). The electrical length of the composite antenna ( 126 ) is then substantially equal to the sum of the electrical length of the PIFA ( 104 ) and extendable portion ( 106 ). An embodiment disconnects the ground path of the PIFA feed structure upon extension of the extendable portion ( 106 ) to provide constant input impedance.