WIDE-BANDED BASE STATION ANTENNA

摘要

A base station antenna (10) includes a matching network that broadbands transmission without requiring adjustment. Using a one-quarter wavelength (1/4 lambda ) or less sperrtopf sleeve (14) in a coaxial arrangement, broadbanding is achieved by adding a second conductor (18) parallel to the transmission line center conductor. A ring inductor (12) is tapped at one end off-center by the second conductor (18). The inductor's step-up end (22) is connected to the antenna (24) with the primary end (26) connected to the transmission line center conductor (28). Mutual inductance may be present, but is not required, between the transmission line center (28) and second (18) conductors. Fringing capacitance between the antenna (24) and the sleeve (14) establishes an "L" network in conjunction with the inductor (12). To protect the inductor (12) from the elements, it is placed inside the antenna (24) near the sleeve (14).