Abstract
The growth of wireless communications in recent years has made it necessary to develop compact, lightweight multiband antennas. Compact antennas can achieve the same performance as large antennas do with low price and with greater system integration. Dual-frequency microstrip antennas for transmission and reception represent promising approach for doubling the system capacity. In this work, a miniaturized dual band antenna operable at 2.45 and 5.8 GHz is constructed by modifying the standard microstrip patch antenna geometry into a fractal structure. In addition to miniaturization and dual band nature, the proposed antenna also removes unwanted harmonics without the use of additional filter component. Using a finite-element-method-based high frequency structure simulator (HFSS), the antenna is designed and its performance in terms of return loss, impedance matching, radiation pattern, and voltage standing wave ratio (VSWR) is demonstrated. Simulation results are shown to be in close agreement with performance measurements from an actual antenna fabricated on an FR4 substrate. The proposed antenna can be integrated with a rectifier circuit to develop a compact rectenna that can harvest RF energy in both of these frequency bands at a reduction in size of 25.98% relative to a conventional rectangular patch antenna.
Highlights
Energy harvesting from external sources such as solar radiation, thermal energy, wind, and radio frequency (RF) emissions has emerged as a promising source of environmentally friendly energy that can provide an alternative to existing resources
A square microstrip patch antenna embedded with modified Sierpinski gasket slots allowed for enhanced miniaturization of a dual-frequency system [21], while a dual wideband, coplanar waveguide (CPW) fed modified Koch fractal printed-slot antenna containing a simple tuning slot that is suitable for WLAN and WiMax operation was proposed by Krishna et al [22]
The dual band antenna was fabricated on an FR4 substrate to verify simulation results
Summary
Energy harvesting from external sources such as solar radiation, thermal energy, wind, and radio frequency (RF) emissions has emerged as a promising source of environmentally friendly energy that can provide an alternative to existing resources. An image is reduced by the same factor in all directions for self-similarity; a self-affine fractal has a different scale factor for different directions This unique feature of fractal geometry can provide additional flexibility in the antenna design, since, by selecting the scale factors appropriately, resonances can be spaced by different factors. Because the electrical length plays such an important role in antenna design, this packing efficiency is useful in developing viable miniaturization techniques Using fractal geometries such as the Sierpinski carpet [4] in antenna design allows for reduction in metallization that enables current path lengthening; this in turn reduces the resonant frequency and decreases the overall dimensions needed to resonate at the required frequency.
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