This paper presents fractal-based inductors for industrial, scientific, and medical applications in a frequency range of 3-500 MHz. The proposed inductors are designed based on the Hilbert space-filling curve and omega-shaped space-filling curve. The fractal inductors are designed and simulated by using a full wave high frequency structural simulator. The Hilbert curve-based fractal loop inductor and omega curve-based fractal loop inductor achieve improvements in the inductance value of 21% to 31% and 11% to 30.88%, respectively, over reported standard inductors. The printed inductors are constructed on 3.2 mm RT/Duroid 5770 substrate and measured with a network analyzer (E8363B). It was found that the experimental results are almost in good agreement with the simulation results. It was also observed that the proposed fractal inductors have poor radiating power, indicating no significant electromagnetic radiation.

This paper presents an efficient modeling of Hilbert fractal inductors by improved feed forward neural network trained hybrid particle swarm optimization and gravitational search algorithm (FNNPSOGSA). The proposed model computes the effective inductance value (L) and quality factor (Q) of Hilbert fractal inductors with metal trace width, effective fractal length, frequency, and oxide thickness as input parameters. In contrast to the traditional feed forward neural network, the proposed FNNPSOGSA has been designed with fewer hidden neurons with much-enhanced learning and generalization capabilities. As a consequence, the proposed model achieves better speed and is as accurate as electromagnetic simulations. From the simulation results, it is proved that the proposed model is a good alternative for complex fractal inductor design.

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Purpose This paper aims to present an efficient method to improve quality factor of printed fractal inductors based on electromagnetic band-gap (EBG) surface. Design/methodology/approach Hilbert fractal inductor is designed and simulated using high-frequency structural simulator. To improve the quality factor, an EBG surface underneath the inductor is incorporated without any degradation in inductance value. Findings The proposed inductor and Q factor are measured based on well-known three-dimensional simulator, and the results are compared experimentally. Practical implications The proposed method was able to significantly decrease the noise with increase in the speed of radio frequency and sensor-integrated circuit design. Originality/value Fractal inductor is designed and simulated with and without EBG surfaces. The measurement of printed circuit board prototypes demonstrates that the inclusion of split-ring array as EBG surface increases the quality factor by 90 per cent over standard fractal inductor of the same dimensions with a small degradation in inductance value and is capable of operating up to 2.4 GHz frequency range.

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