This dissertation presents four dual-band printed monopole antennas. There are three printed monopole antennas operating in 2.4 GHz and 5.2/5.8 GHz WLAN bands, and a dual wideband printed monopole operating applies in 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands. The proposed antennas mainly use two approaches to achieve dual-band and dual wideband operations. The first method uses two different resonant paths in radiating monopole to excite two desired operating frequencies. The proposed configuration using the first method is a printed G-shaped monopole antenna. The second method places the conductor-backed plane on the other side of the radiated monopole to perturb its resonant behaviors for enhancing impedance bandwidth. Three configurations using the second method are proposed. The one with the best wideband performance is a printed rectangular monopole antenna with a trapezoid conductor-backed plane. Measured results for the proposed antennas show satisfactory performances and good agreement with the simulated results.

Yes / Empirical results of an electrically small printed monopole antenna is described with fractional bandwidth of 185% (115 MHz–2.90 GHz) for return-loss better than 10 dB, peak gain and radiation efficiency at 1.45 GHz of 2.35 dBi and 78.8%, respectively. The antenna geometry can be approximated to a back-to-back triangular shaped patch structure that is excited through a common feed-line with a meander-line T-shape divider. The truncated ground-plane includes a central stub located underneath the feed-line. The impedance bandwidth of the antenna is enhanced with the inclusion of meander-line slots in the patch and four double split-ring resonators on the underside of the radiating patches. The antenna radiates approximately omnidirectionally to provide coverage over a large part of VHF, whole of UHF, entire of L-band and some parts of S-band. The antenna has dimensions of 48.32×43.72×0.8 mm3, which is corresponding with the electrical size of 0.235λ_0×0.211λ_0×0.003λ_0, where λ_0 is free-space wavelength at 1.45 GHz. The proposed low-profile low-cost antenna is suitable for application in wideband wireless communications systems. / H2020-MSCA-ITN-2016 SECRET-722424 and UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1