Abstract:
A textile based perturbed Sierpinski fractal antenna for multiband applications is presented in this
thesis. The proposed antenna is designed with three iterations and with a scale factor of 1.5 that
characterizes the Sierpinski fractal geometry. Denim with dielectric constant of 1.8 is selected for
the textile substrate material. For practical implementation and to give mechanical support for
testing and measurements, a new design with strip line feeding and PCB frame is proposed. The
simulation of proposed antenna is carried out in EM simulation software HFSS. The design is
optimized using extensive parametric analysis. The simulated results displayed a multiband
behavior by showing resonance at four different frequencies of 0.50GHz, 1.725GHz, 2.7GHz and
4.15GHz with return loss of -23.6dB, -19.2dB, -29.3dB and -32.4dB respectively. Antenna showed
a good bandwidth of 145MHz, 202MHz, 254MHz and 405 MHz with a gain of 0.75dBi, 2.7dBi,
2.39dBi and 2.59dBi at four resonance frequencies respectively. Moreover, bending and on-body
analysis is also carried out to ensure reliable performance of the antenna. Bending and on-body
simulations showed a shift in resonance frequencies. For health safety assurance, SAR values are
also computed as 0.005w/kg, 0.036w/kg, 0.865w/kg and 1.429w/kg that are less than the standard
SAR limits of 2w/kg. The antenna is fabricated using Denim fabric as substrate with an average
thickness of 0.7mm and copper tape is used for the conducting patch. The measured results showed
resonance at 0.47GHz, 1.73 GHz, 2.52GHz and 4.01GHz with return loss of -4.23dB,
-9.84dB, -15.14dB and -7.96dB respectively . The measured results, although not as good as the
simulated results, clearly display a multiband behavior and exhibit a reasonable performance for
an antenna fabricated on textile material. The difference in simulated and measured results can be
reduced by minimizing fabrication issues. The proposed antenna structure is suitable for wearable
textile multiband applications.
