Abstract-A compact wideband dual-frequency microstrip antenna is proposed in this paper. By employing an offset microstrip-fed line and a strip close to the radiating edges in the circular slot patch, an antenna operating at dual frequency with the impedance bandwidth of 26.2% and 22.2% respectively is presented. By attaching a strip to the radiating edges opposite to the microstrip-fed line, this alters the current distribution and radiation on the antenna at the second resonant frequency. The second frequency is also tunable by varying the lengths of the microstrip-fed line. It is demonstrated that the proposed antenna covers the widebands of UHF and microwave for RFID application. A good agreement is obtained between the simulated and experimental results.

Abstract-A broadband inverted E-H shaped microstrip patch antenna is proposed and experimentally investigated. The antenna employs novel E-H shaped patch with L-probe feed technique. Prototype of the proposed antenna has been fabricated and measured for electromagnetic analysis including the impedance bandwidth, radiation pattern, and antenna gain. The designed antenna has a dimension of 80 mm by 50 mm, leading to broad bandwidths covering 1.76 GHz to 2.38 GHz. Stable radiation patterns across the operating bandwidth are observed. In addition, a parametric study is conducted to facilitate the design and optimization process.

Plane wave scattering from a flat surface consisting of two periodic arrays of ring elements printed on a grounded dielectric sheet is investigated. It is shown that the reflection phase variation as a function of ring diameter is controlled by the difference in the centre resonant frequency of the two arrays. Simulated and measured results at X-band demonstrate that this parameter can be used to reduce the gradient and improve the linearity of the reflection phase versus ring size slope. These are necessary conditions for the re-radiating elements to maximise the bandwidth of a microstrip reflectarray antenna. The scattering properties of a conventional dual resonant multilayer structure and an array of concentric rings printed on a metal backed dielectric substrate are compared and the trade-off in performance is discussed.

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Abstract-A new high gain wideband L-probe fed inverted EE-H shaped slotted (LEE-H) microstrip patch antenna is presented in this paper. The design adopts contemporary techniques; L-probe feeding, inverted patch structure with air-filled dielectric, and EE-H shaped patch. The integration of these techniques leads to a new patch antenna with a low profile as well as useful operational features, as the broadband and high gain. The measured result showed satisfactory performance with achievable impedance bandwidth of 21.15% at 10 dB return loss (VSWR ≤ 2) and a maximum gain of 9.5 dBi. The antenna exhibits stable radiation pattern in the entire operating band.

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Abstract-A new design technique of microstrip patch antenna is presented in this paper. The proposed antenna design consists of inverted patch structure with air-filled dielectric, direct coaxial probe feed technique and the novel slotted shaped patch. The composite effect of integrating these techniques and by introducing the new multislotted patch, offer a low profile, high gain, broadband, and compact antenna element. A wide impedance bandwidth of 27.62% at −10 dB return loss is achieved. The maximum achievable gain is 9.41 dBi. The achievable experimental 3-dB beamwidth (HPBW) in the azimuth and elevation are 60.88 • and 39 • respectively at centre frequency.

The electromagnetic interface between the antenna and the human head is reduced with ferrite materials and metamaterials. The reduction of Specific Absorption Rate (SAR) with materials and metamaterials is performed by the finite-difference time-domain method with Lossy-Drude model by CST Microwave Studio. The metamaterials can be achieved by arranging split ring resonators (SRRs) periodically.The SAR value has been observed by varying the distances between head model to phone model, different widths, different thicknesses, and different heights of materials and metamaterial design. Materials have achieved 47.68% reduction of the initial SAR value while metamaterials achieved a reduction of 42.12%. These results can endow with supportive information in designing the wireless communications equipments for safety compliance.