MULTIPLE FREQUENCY ANTENNA

摘要

An antenna having a resonant structure, comprises an antenna element (11) and an adjacent electrode (17A) and control means (22,25) for changing a resonance frequency of the antenna element. The control means may comprise a conductive membrane (17A) spaced from the antenna element. The resonance frequency then is changed by flexing the membrane, conveniently by applying a potential difference between the membrane and an adjacent control electrode.