Design and analysis of multiband circularly polarized antenna for modern wireless applications

In this dissertation, new five compact multiband printed antennas have been designed, and analyzed. The first two antennas have a dual-sense circular polarization while the others are single-sense circular polarization. The first one has been designed based on an open-loop hexagonal monopole radiator with two stair-shaped slits in a partial ground plane. Five operating bands with different polarization are obtained. Three bands out of these five are circularly polarized (CP) while the other are linearly polarized (LP). The -10 dB impedance bandwidths (IBWs) are (1.55-1.72 GHz), (2.51- 2.64 GHz), (3.1-3.31 GHz), (4.08-5.83 GHz), and (6.14-6.7 GHz), while the 3 dB axial ratio bandwidths (ARBWs) are (1.6-1.75 GHz), (4.54-4.9 GHz), and (6.21-6.49 GHz). Also, this antenna shows a triple sense (right hand, left hand, right hand) CP, bidirectional radiation patterns. The measured gains are 1.75 dBi, 3.72 dBi, 3.2 dBi, 5.87dBi, and 7.61 dBi at frequencies 1.65 GHz, 2.55 GHz, 3.20 GHz, 4.75 GHz, and 6.35 GHz respectively. Overall dimensions are 65 mm × 45 mm × 1.6 mm. Another two stair-shaped slits in the partial ground plane have been added with a pair of rectangular strips. The IBWs are (1.478-1.714 GHz), (2.54-2.72 GHz), and (4.29-4.89 GHz), respectively. The measured 3-dB axial ratio bandwidths (ARBWs) are (1.510- 1.606 GHz) and (4.035-5.07 GHz) for the lower and the upper band respectively. The measured gains are 2.5 dBi, 3.6 dBi, and 5 dBi at frequencies 1.575 GHz, 2.55 GHz, and 4.5 GHz respectively. The side length of this antenna has been increased to be 70 mm. The last three proposed antennas are fed by CPW with dimensions 40 mm ×40 mm ×1 mm. One of these three antennas is a slotted square ring with two rectangular strips, which are located at the opposite corner, and three bands are obtained. The IBWs are: (3.59-5.01 GHz), (7.64 to 8.43 GHz), and (10.81 to 11.28 GHz) whereas ARBWs at 3-dB are: (3.15-4.69 GHz), (7.77-8.17 GHz), and (10.84-11.25 GHz) GHz. The simulated gains are 3.75 dBi, 3.2 dBi, and 4.62 dBi at center frequencies 4.5 GHz, 8 GHz, and 11 GHz respectively. In the first updated antenna, the CP characteristic in the first band has been boosted by adding an inverted L-strip to the ground plane on the far corner of the radiator after it was not strong in the previous antenna. The IBWs for three bands are: (3.2-5.39 GHz), (7.55 to 8.21 GHz), and (10.79 to 11.31 GHz) whereas ARBW are: (3.32-4.58 GHz) and (10.79-11.13 GHz). The simulated gains are 2.65 dBi, 3.9 dBi, and 5.3 dBi at center frequencies 3.6 GHz, 8 GHz, and 11 GHz respectively. The second modified antenna demonstrated a new band around 5.8 GHz. The IBWs for four bands are: (3.72-4.88 GHz), (5.62-5.89 GHz), (7.68-8.27 GHz), and (10.83-11.33 GHz) whereas ARBWs are: (3.17-3.64 GHz), (5.62-5.89 GHz), and (10.64-11.1 GHz). Concerning simulated gains are 2.6 dBi, 2.1 dBi, 3.6 dBi, and 4.4 dBi at frequencies 3.6 GHz, 5.8 GHz, 8 GHz, and 11 GHz respectively. Finally, all the proposed antennas in this work have been designed using an FR4 substrate with relative permittivity of 4.4. The simulation results have been evaluated by using an HFSS simulator from Anasys.