Abstract-Helical antenna and planar inverted-F antenna (PIFA) are two commonly used handset antennas. This paper presents a comprehensive study on the performance of a dual band PIFA and a dual band helical antenna designed for operating in GSM900 and DCS1800 frequency bands. Radiation patterns and VSWR of these antennas are computed in free space as well as in the presence of head and hand. The specific absorption rate (SAR) of the helical antenna is calculated and compared with that of the PIFA handset antenna. The peak average SAR in the head is compared with SAR limits in the safety standards and so the maximum radiation power of each antenna is determined. In addition, radiation efficiencies of these handset antennas are computed in the presence of head and hand. All numerical simulations are performed using the Ansoft HFSS software. Numerical simulations results are in good agreement with published measurement results.

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A method of ‘mode shifting’ is presented for realisation of triple‐mode and dual‐mode filters, in which the resonant frequency of one mode is shifted near to the resonant frequency of another mode using a perturbation. To realise a triple‐mode filter, a single‐layer substrate‐integrated waveguide (SIW) square cavity is perturbed by introducing vias at the middle of the structure. This perturbation causes mode shifting of the dominant mode (TE101) near to the next modes (TE102 and TE201). Operation of this triple‐mode resonator is analysed and resonant frequencies of the perturbed cavity are obtained theoretically. A triple‐mode filter is realised using this resonator and the filter is modelled by a coupling matrix based on the global eigenmodes. Moreover, by using the mode shifting technique, a novel dual‐mode bandpass filter with half‐mode SIW (HMSIW) structure is presented. Both the triple‐mode SIW and dual‐mode HMSIW filters are fabricated on a single‐layer substrate using a printed circuit board process.

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Abstract-Water bolus is used in microwave hyperthermia of cancer treatment to control the body surface temperature. In this paper the effect of water bolus on SAR distribution is investigated in the muscle layer of a three layered tissue model. Both the SAR penetration depth and the effective field size (EFS) are computed and compared in presence and in absence of the water bolus. Results are provided for distilled and fresh water with three different thicknesses of water bolus. All numerical simulations are performed using the Ansoft HFSS software. Numerical simulation results are in good agreement with published results.