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This paper presents a novel technique for enhancing the slot antenna bandwidth using special dispersive materials for the first time. The dispersive material whose relative permittivity is inversely proportional to the frequency by the power of n is selected and exploited for antenna bandwidth enhancement and size reduction. The concept and theory behind this work are explored. A slot antenna loaded with the new material is proposed and it is shown that the bandwidth of slot antennas using the material with power ${n}{=}2$ can be significantly improved with more than 4 times larger than the traditional case ( ${n}{=}0$ ). The simulated and measured results show excellent properties for wideband improvement and miniaturization which further demonstrates that dispersive materials can open a new path for developing wideband devices and antennas for future wireless communication applications.

In this paper, a reconfigurable metal rim antenna with a small clearance and compact structure for 4G/5G smartphones is proposed. It consists of the system ground plane and a metal rim with two slits, in which a U-shaped slot of 1 mm (the smallest) clearance is realized between the system ground and metal rim. The theory of characteristic modes is applied to analyze the eigenmodes of the antenna so as to aid the optimum design. The characteristic modes (CMs) in the band of interest are studied, and an inductive coupling exciter is identified as the best since three CMs can therefore be generated in the lower frequency band (0.69-0.96 GHz), and an SP4T switch can be utilized to increase the bandwidth of the whole lower band. A prototype antenna of the optimized design was fabricated. A good agreement was obtained between the measured and simulated results. The 6-dB frequency bands are the lower band (0.69-0.96 GHz), the middle band (1.7- 2.7 GHz), and the higher 5G band (3.4- 3.6 GHz), respectively, and the total efficiencies are over 50% in all these frequency bands. They indicate that the antenna is a very good candidate for smartphone applications.

Total radiated power (TRP) is commonly accepted as an important figure of merit (FoM) for evaluating the over-the-air (OTA) performance of wireless devices enabled by the emerging fifth generation (5G) mobile communication technology. The statistically homogeneous and isotropic electromagnetic (EM) environment created by a reverberation chamber (RC) makes it an accurate, efficient, and economic testing facility for TRP measurement. In this paper, an improved analytical uncertainty model which is based on the average Rician K-factor (Kavg) and the number of independent samples is proposed for TRP measurement using an RC. It has the flexibility to allow different stirring configurations in the calibration stage and the measurement stage, and gives insight into the measurement uncertainty without the tedious and inefficient empirical estimation processes. Estimators of Kavg are modelled and analyzed. Specifically, the maximum likelihood estimator (MLE) of Kavg is validated by the Monte Carlo simulation, and its unbiased correction is derived accordingly for improved uncertainty model accuracy. Extensive 9-Point estimation measurements are also conducted in order to evaluate the performance of the proposed analytical model.