Muhammad Ali Babar Abbasi

Textile antenna for body centric WiMAX and WLAN applications

Body centric wireless communication refers to inter human and intra human connectivity for various medical and rescue application. A compact and flexible printed textile antenna operable at 5.2GHz for WiMAX and WLAN application has been presented. Wearable 1mm thick blue jeans having relative permittivity 1.67 and loss tangent of 0.01 has been used as substrate material. Return loss, VSWR and radiation pattern have been presented to show the good agreement between the simulated and measured results. Free space and near body scenarios were considered separately while designing and in measurement of results. The proposed antenna exhibits omnidirectional radiation pattern for near body case with suitable gain of 5dB for body centric applications. Simulations were carried out using HFSS (High Frequency Structural Simulator) and measurements were performed using vector network analyzer and anechoic chamber.

Miniaturization of UWB Antennas on Organic Material

Three planar, CPW-fed, UWB antennas with increasingly reduced size are presented and the miniaturization method is discussed. The first antenna is a CPW-fed elliptical slot with an uneven U-shaped tuning stub, the second antenna is a cactus shaped monopole, and the third one is a miniaturized version of the cactus shaped monopole antenna. All presented antennas have a simulated and measured return loss below −10 dB over the 3.1 to 10.6 GHz UWB frequency range and mostly omnidirectional radiation patterns. The proposed antennas are fabricated on liquid crystal polymer (LCP). The CPW-fed slot antenna requires an overall board dimension of 38 mm × 40 mm, and the evolved cactus monopole is confined in a 28 mm × 32 mm board, while the final miniaturized cactus monopole is printed on 28 mm × 20 mm board, resulting in a 41% and 63% size reduction, respectively. Using both simulations and measurements, the paper analyzes the response of all three antennas and discusses and demonstrates the effectiveness of the implemented miniaturization method.

On the Use of Tunable Power Splitter for Simultaneous Wireless Information and Power Transfer Receivers

The use of a tunable power splitter (PS) as a constituent component of a simultaneous wireless information and power transfer (SWIPT) system is discussed. Two varactor diodes are used to achieve a tunable output power ratio 2 :  3 varying from 1 : 1 to 1 : 10 under good matching conditions. The SWIPT system that operates at 2.4 GHz consists of a typical patch antenna, cascaded with the tunable PS, and a voltage doubler rectifier. The constituent components were implemented and tested as stand-alone devices and were subsequently combined in a measurement system using interconnectors. The effect of the tunable PS was explored with respect to the SNR measurements on the port that is intended for the information decoding receiver and the DC voltage measurements on the termination load of the rectifier that is connected directly on the energy harvesting port of the tunable PS. A spectrum analyzer is used for the SNR measurements while the input power is controlled using a signal generator. Both wireless power transmission and on-board measurements verify that the harvested energy can be maximized by using the minimum SNR at the information decoding branch at the expense of DC power consumption required for the biasing of the varactor diodes.