Abstract-In this paper, the performance of the mobile phone handset antenna-chassis combination is analyzed based on an approximate decomposition of the waves on the structure into two resonant wavemodes: the antenna-element wavemode and the chassis wavemode. A double resonator equivalent circuit model is presented and used to estimate the impedance bandwidth and the respective distribution of radiation losses with typical parameter values at 900 and 1800 MHz. It is noticed that at 900 MHz, the radiation losses by the antenna element wavemode represent typically less than 10% of the total power. Thus, the antenna element works mainly as a matching element, which couples to the lowresonant wavemode of the chassis. At 1800 MHz, the contribution of the antenna element wavemode is larger. By enhancing the coupling and by tuning the chassis resonance, it is possible to obtain an impedance bandwidth of over 50% (6-dB return loss) at both at 900 and 1800 MHz. The results given by the equivalent circuit study are fully supported by those of three-dimensional phone-model simulations, including calculation of the SAR and efficiency values. In prototyping, the 6-dB bandwidth of 5.5% was obtained at 980 MHz with a nonradiating coupling element with a volume of 1.6 cm 3 on a 120-mm-long chassis.

Abstract-In this paper, internal low-volume antenna structures for mobile terminals are studied. The work concentrates on the possibilities to reduce the volume of mobile terminal antenna elements by efficiently utilizing the radiation of the currents on the mobile terminal chassis. Essentially nonresonant coupling elements are used to optimally couple to the dominating characteristic wavemodes of the chassis. The antenna structures are tuned to resonance with matching circuits. During the last few years, the approach has achieved growing interest-also among industrial manufacturers of mobile terminals. There exist, however, no systematical feasibility and performance studies of the idea. During the work, two antenna models with very low-volume coupling elements are designed and in total four prototypes are constructed. The simulation and measurement results show that the studied antenna concept is a very promising alternative for traditional antenna technologies. The presented analysis provides useful and novel information for the designs of the future low-profile and low-volume mobile terminal antennas.

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A novel thin stacked shorted patch antenna for the 1800MHz frequency band is presented. The antenna is dual-resonant and small in size. It has a very low profile and a bandwidth of almost 10%, which is sufficient, for example, for GSM1800 or GSM1900 systems. The radiation pattern of the antenna is suitable for directive cellular handset antenna applications.

The theory of propagating waves near a surface is reviewed with an eye to gain insight into the mechanisms involved, and to provide analytical-based models, for power-efficient on-body propagation. The Zenneck wave, and in particular the Norton wave, are appraised as candidate mechanisms for the propagation. For flush-mounted ("band aid") antennas, desired for on-body sensors, the Norton wave is the only direct propagation mechanism between the sensors. The Norton wave fits very well to simulation results presented here, and comparisons are also made with available published physical experiments, although these measurements typically feature the optical paths of elevated, or non-flush, antennas.