Log-periodic antenna with a passband and a stopband

摘要

A log-periodic dipole antenna and its design method comprises: providing a log-periodic antenna with a number of dipoles for transmitting or receiving electromagnetic signals in a pass-band while rejecting electromagnetic signals in a stop-band, without using any external filters. This is obtained in the high-frequency-cut embodiment of the invention by optimizing the first few dipole lengths, and thereafter following the classical Isbell and Carrel’s gradually increasing pattern for the rest of the dipole lengths. The dipoles are on one or more metallic booms and non-monotonically increase in length along an axis of the antenna. The first dipole may be longer than the second dipole. The antenna design method may be utilized to design antennas capable of operating in any pass-band or stop-band just by optimizing the lengths of dipoles, and spacing between dipoles, depending on the desired frequency of operation. A preferred embodiment may provide a low insertion loss for the antenna in a pass-band and a high insertion loss in the stop-band. The antenna may possess highly directional characteristics and provide a relatively flat gain between 7dBi and 12dBi, depending on the number of dipoles used.