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In this article, a compact tuneable F‐slot monopole antenna for mobile handset applications, covering the DCS, PCS, and UMTS frequency bands, is presented and studied. An F‐shaped slot is embedded in a rectangular monopole patch to accommodate the varactor. The tuning is accomplished by applying a lumped capacitor (varactor) across the slot arms of the patch. By varying the capacitance values of loaded capacitor from 0.5 to 3 pF, the antenna is capable of achieving high tuning ranges from 1.70 to 2.15 GHz. The antenna performance is characterized in terms of the reflection coefficient, radiation pattern, and power gain. The predicted and measured results show fairly good agreement and confirm satisfactory impedance bandwidth characteristics and consistent radiation patterns over the tuned frequency range. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:794–802, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26649

This paper studies the effect of nonlinear and linear crosstalk in a MIMO (multiple in, multiple out) transceiver. These effects are mainly due to the power amplifier (PA) nonlinear behaviour and mutual coupling of antennas in the MIMO transmitter. The effects of the crosstalk interference on the signal performance are studied based on the measured error vector magnitude (EVM) at the transmitting antennas. The simulation and measurement results show that PA nonlinearity and RF crosstalk need to be considered in the design process.

A planar inverted-F type reconfigurable antenna with slot is presented. The antenna can cover frequency bands which include Digital reconfigurability of the proposed antenna is achieved by attaching lumped capacitor over the slit of the radiator with values range from 1.5-4pf. The measured and simulated results reveal that the fabricated proposed antenna is capable of obtaining tunable frequency ratio from 1850MHz to 2200MHz with overall size of 21×13.5×5 mm 3 that makes it suitable for handset applications and can be easily integrated inside commercial mobile handsets.

Abstract. RF power amplifiers in mobile WiMAX transceivers operate in an inherently nonlinear manner. It is possible to amplify the signal in the linear region, and avoid distortion, using output power back-off; however, this approach may suffer significant reduction in efficiency and power output. This paper investigates the use of Doherty techniques instead of back-off, to simultaneously achieve good efficiency and acceptable linearity. A 3.5 GHz Doherty RFPA has been designed and optimized using a large signal model simulation of the active device, and performance analysis under different drive levels. However, the Doherty EVM is generally poor for mobile WiMAX. Linearity may be improved by further digital pre-distortion, and a simple predistortion method using forward and reverse AM-AM and AM-PM modeling. Measurements on the realized amplifier show that this approach satisfies the EVM requirements for WiMAX base stations. It exhibits a PAE over 60%, and increases the maximum linear output power to 43 dB m , whilst improving the EVM.