Spectrum Sensing Fractal Antenna for Cognitive Radio Application
Ashwini Kumar, Ashish Kumar, Gurmeet Singh, Bikash Chandra Sahoo, Soumya Ranjan Mishra · 2024
This paper reports the design of a novel Grapheme Nanomaterial based spectrum sensing fractal antenna for cognitive radio applications in fixed satellite and radio navigation bands. The major manufacturing process for the fabrication of such type of antennas includes the fabrication of radiating metal patch (copper or aluminum or similar other conducting metal) over the surface of a suitable dielectric. However, production of copper or aluminum or any other metal involves various chemical and physical processes, which pollute the environment vigorously. To circumvent this specific problem, an attempt is made in the present work to replace the conducting metal with grapheme nanomaterials for the design of the radiating patch of the proposed antenna (PA). Graphene nanomaterial-based patch antennas reported till-date, suffer from the drawback of lower gain and/or lower efficiency as well as failure in omnidirectional radiation while covering the entire range of its operation in the specified band. In the next step, however, to overcome these problems, the elongated side of rectangular patch is transformed into Minkowski Fractal Geometry. This has resulted in appreciable enhancement of antenna bandwidth. As an explicit outcome, the PA exhibits wideband response having an impedance bandwidth of 2.3 GHz that extends from 2.72 to 5.03 GHz. Further, the microstrip-feed in the proposed design is also converted into step-feed to further improve the impedance matching as well as improved radiation characteristics of the PA. This modification in the design has resulted much improvement in the peak gain of 4.2 dBi at 4.57 GHz with excellent omni-directional radiation pattern, which is of course, the essential requirement of the spectrum sensing antennas. Moreover, in order to validate the proposed design, the results of grapheme-based fractal antenna are also compared with its conventional copper counterpart. It is found that the proposed grapheme antenna indicates a higher degree of impedance matching and identical radiation patterns to its conventional copper counterpart.