Single-feed triple band circularly polarized spidron fractal slot antenna

Abstract

In this paper, the design of a single-feed triple-band circularly polarized Spidron fractal slot antenna is presented. The proposed antenna is composed of a Spidron fractal slot, a Z-shaped slit, and two L-shaped slits to realize triple-band circular polarization operation. A simple 50 Ω microstrip line is utilized to feed the proposed antenna. A conducting reflector is also used to reduce back radiation, thereby enhancing the forward antenna gain. The proposed antenna has total dimensions of 40.7 mm×40.7 mm×18.52 mm (0.42λ×0.42λ× 0.19λ) and was fabricated and tested. The experimental results show that the proposed antenna has -10 dB reflection coefficient bandwidths from 2.76 GHz to 3.13 GHz and from 3.56 GHz to 6.22 GHz. The measured 3 dB axial ratio bandwidths are 2.28% (3.04-3.11 GHz) for the lower band, 7.15% (4.18-4.49 GHz) for the middle band, and 2.6% (4.93-5.06 GHz) for the upper band. The peak gains within the -10 dB reflection coefficient bandwidths are 3.41 dBic and 6.29 dBic, respectively.