T Technical topics

摘要

During 1998 and 1999, (April, June, August, 1998 and January, June 1999) a series of items was published in 'TT' on fractal antennas, based largely on the pioneering work of Professor Nathan ("Chips") Cohen, N1IR, as published in a series of articles totalling over 50 pages in Communications Quarterly. Fractals represent a class of geometry with unique properties of particular interest to computer scientists and are proving enticing for antenna designers. As quoted in the IEEE A & P Magazine article discussed below, "Fractals are space-filling contours, meaning electrically-large features can be efficiently packed into small areas. Since electrical lengths play an important role in antenna design, this efficient packing can be used as a viable miniaturisation technique." Fractal designs have been developed for dipoles, loops, patch ele- ments and linear phased arrays. A facet of a fractal loop brought near to resonance is the raised input impedance.