Miniaturization of Logarithmic Spiral Antenna Using Fibonacci Sequence and Koch Fractals

摘要

This paper discusses recently reported Fibonacci spiral and Koch fractals to reduce the footprint of a logarithmic spiral antenna (LSA). The Fibonacci spiral has been used to approximate the two continuous peripheries of logarithmic spiral. The inherent quarter circular sections of Fibonacci spiral form the discontinuous base for fractals to be superimposed upon. 1^st and 2^nd iterations of Koch curve have provided 23.1% and 48.3% of miniaturization respectively as compared to logarithmic spiral antenna with size of pmb78×50mm^pmb2. These antennas without backing work efficiently in the frequency band of 2 GHz to 12 GHz with average gain of 5 dB and 98.7% of radiation efficiency. They radiate bidirectional beam of circularly polarized nature when excited with unbalanced feed.