ANTENNA

摘要

A parasitic antenna element (20) comprises first and second switches: one at the base (PIN diode 22) and one approximately half way along the parasitic element (PIN diode 28). The lower half of the parasitic element is realized as a coplanar waveguide with a central conductor (32). This not only provides a convenient method for biasing the second PIN diode (28), but the outer conductors (24, 26) provide shielding and reduce coupling of the RF energy into the bias circuitry. The first switch located near the base of the antenna element is provided for selectively coupling the antenna element to a ground plane for quenching a first current mode. The second switch located along the antenna element selectively partitions the antenna element into first and second portions, thereby quenching higher order current modes.