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ABSTRACT A dual band Artificial Magnetic Conductor (AMC) with capacitive tuning of reflection phase at lower band frequency is proposed. The AMC operates at upper band of fixed frequency at 5.8 GHz while the lower band reconfigurable frequency is from 2.5 GHz up to 3.1 GHz. The simulated reconfigurable frequencies are 2.5, 2.62, and 3.10 GHz. The corresponding resonance structure for each band is circular patch and circular slotted ring with single capacitor per AMC unit cell. Subsequently, the AMC is incorporated with conventional UWB antenna. The effects of AMC capacitive tuning to UWB antenna performance are studied in terms of frequency reconfigurability, gain, and radiation patterns. Measurement is also carried out for the reflection coefficient and radiation patterns. Parametrical studies of the antenna such as the misalignment between the top and bottom substrate layers, air gap between the substrate layers, and capacitance tolerance of the capacitor to the reflection coefficients are also discussed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2422-2429, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT A wideband antenna fed by a coplanar waveguide (CPW) with reconfigurable function is presented. The wideband function is achieved from 1.39 GHz to 8.11 GHz using an elliptical radiator with a CPW feed line. Meanwhile, three pairs of slot dipoles which are fed by CPW are used to achieve triple-band function at 2.4 GHz, 3.5 GHz and 5.2 GHz. Four ideal switches are placed on the proposed antenna. The proposed antenna is designed, simulated, fabricated and tested. All simulated and measured results of return loss, radiation pattern and gain are presented. Good results of return loss and radiation pattern are obtained thus verifying that the proposed antenna is suitable for future multimode radio systems. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2079-2082, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a technique to enhance the bandwidth of a rectangular dielectric resonator antenna using a circular slot. The structures are designed and simulated using CST Microwave Studio software, and it is found that the circular slot exhibits a bandwidth of 36.44% (0.92-1.33 GHz). The circular slot is compared with the rectangular slot. It is shown that the rectangular slot produces a bandwidth of 6.39% (1.06-1.13 GHz). Both structures exhibit similar radiation patterns with slightly different gains at 3.10 and 3.25 dBi. The bandwidth is enhanced more than five times using the circular slot, compared to the rectangular slot. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:506-509, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT A composite right-/left-handed transmission line metamaterial antenna with enhanced bandwidth and efficiency is proposed. The antenna combines zeroth-order resonant (ZOR) and positive-order resonant (POR) modes for the bandwidth enhancement. An asymmetrical coplanar waveguide technique is used to feed the antenna and also to achieve certain degree of compactness. The overall size of the antenna is 0.32λ0 × 0.38λ0 × 0.012λ0 (40 × 48 × 1.52 mm) at 2.4 GHz. Simulation results show that a bandwidth enhancement of 41% is obtained with the radiation efficiencies of 95 and 97% for the ZOR and POR modes, respectively. The measured impedance bandwidth shows that the antenna has potential applications for WLAN (2.39-2.45 GHz) and WiMAX (2.5-2.69 GHz) operations. The simulated and measured antenna performances in terms of return loss and the radiation patterns are presented and compared. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:252-256, 2015 [ABSTRACT FROM AUTHOR]