Design and Analysis of Hexagonal Shaped Fractal Antennas

Abstract

In this report three antenna designs using fractals have been proposed. Fractal is a concept which is being implemented in microstrip antenna to have better characteristics than conventional microstrip antenna. In the first design, a hexagonal shaped monopole fractal antenna for wideband application is designed. The proposed fractal-like geometry is implemented on a microstrip fed planar hexagonal monopole antenna. The iterated hexagonal fractal patch and modified ground plane are employed to achieve the desired wideband characteristics. A notch is also achieved by introducing slits in ground plane. In the second proposal, a new hexagonal shaped patch with modified hexagonal carpet ground plane antenna for multiband application is proposed. Its structure is based on carpet fractal geometry introduced in ground plane. The resonance frequency of a conventional hexagonal patch with full ground is lowered by removing carpet of hexagonal elements from the full ground plane. The antenna is optimized for a dual band operation. The last antenna is the smallest of all the three antennas obtained by taking a hexagonal patch of 8mm side on a fractal ground plane and whole dimension of 30x30mm2. Firstly, full ground plane is taken and studied. Then ground plane is modified by introducing and etching out Symmetrical Vertical Pyramidal Structure (SVPS). All antennas are simulated using CST Microwave Studio Suite 12. For all designs, low cost and readily available FR-4 substrate of relative permittivity of 4.4 and height 1.6mm has been used and fed with 50-ohm microstrip line. All antennas are measured to validate the simulated results. The measured antenna parameters such as return loss, radiation patterns and gain of the proposed antennas are found well matched to the simulated results.