Muhammad Irfan Khattak

Bicep mounted low profile wearable antenna based on a non-uniform EBG ground plane - flexible EBG inverted-l (FEBGIL) antenna

This novel paper presents a low profile antenna based on the properties of a non-uniform electromagnetic bandgap (NU-EBG), i.e. a non-uniform high impedance surface (NU-HIS). The structure, referred to as Flexible EBG Inverted-L (FEBGIL) antenna, is an efficient wearable antenna incorporating a planar inverted-L element adjacent to some non-uniformly spaced high impedance elements. While the bandwidth is approximately 10% at 1.85 GHz, the overall electrical size is quite small providing an ideal condition for the antenna to be worn on biceps (upper arms). This design is able to minimize electromagnetic interaction with the body on which it is worn and therefore can reduce Specific Absorption Rate (SAR) and degradation in radiation efficiency.

A wearable flexible multi-band antenna based on a square slotted printed monopole

This paper presents a novel flexible wearable multi-band printed monopole antenna on a neoprene substrate. Bands covered are GSM 900 (890-960 MHz), DCS (1710- 1880 MHz), PCS (1850-1990 MHz), UMTS (1920-2170 MHz) and WLAN 2.4 GHz (2400-2484 MHz) bands. The antenna is optimised for performance on the body.

Adaptive fuzzy fractional-order sliding mode controller for a class of dynamical systems with uncertainty

A sliding mode control (SMC) strategy is proposed for a second-order non-linear system using fractional calculus and adaptive fuzzy compensator, named fuzzy fractional-order SMC (FFOSMC). The major contribution of this research includes the formulation of a robust fractional-order controller based on a novel non-integer sliding manifold. The proposed controller utilizes reduced discontinuous switching gain using a fuzzy logic system. A fractional-order adaptation law is derived to update the fuzzy logic system, which has more degrees of freedom to achieve the desired performance. The stability of the closed-loop system is guaranteed using fractional-order Lyapunov theory. The parameters of the proposed control method are optimized using Simulink response optimization. Finally, the performance of the FFOSMC is fully investigated and compared with a conventional SMC controller and an integral SMC controller. From simulation results, it is concluded that the proposed algorithm is effective and more robust.

A study of perturbations due to antennas in close proximity with the human body and body simulating liquid filled phantoms at 1.8GHz

This paper deals with perturbations caused to the matching of a simple generic square planar patch in close proximity with a human male torso and a rectangular box phantom filled with tissue simulating liquid. The operating frequency is 1.8GHz and the isolated variable is return loss (S11). Results presented here are useful in assessing optimal antenna/body separation for wearable antennas in Body Area Networks using both intra and inter wireless connectivity. Research indicates that a flat section phantom will tend to produce an optimal return loss closer to its surface than an actual human test subject.

Understanding Body-centric antennas

As of September 2010 trends suggested that disruptive technologies were likely to include wireless communications devices integrated into clothing. A new set of antennas is required for Body-centric applications. Such antennas will form a key component in Body area networks (BANs) in which transmitters and receivers are co-located on the body, implanted under the skin, directly attached to the skin or integrated into clothing. Notable drivers are multimedia, medical and military applications. These drivers combined with the geo-sensitive facilitators of global positioning system (GPS), Galileo global navigation satellite system (GNSS), cellular, unlicensed 802.11x and short range technologies such as Bluetooth and UWB have made Body-centric antennas fundamental in achieving the desired low power signal budgets required.

Fractional order fuzzy terminal sliding mode control of aerodynamics load simulator

Fractional order adaptive fuzzy continuous non-singular terminal sliding mode control is proposed for electrical aerodynamics load simulator system which is subjected to extra torque disturbance and parametric uncertainties. A fractional order sliding surface is constructed and a continuous non-singular terminal sliding mode control law is derived to ensure faster convergence and precise control without singularity problem. Fractional order adaptive fuzzy logic system is used to estimate the unknown extra torque disturbance. Moreover, nonlinear friction is compensated using LuGre model. Practically, electrical aerodynamics load simulator system is affected by additional un-modeled dynamics due to uncertainty in system parameters and friction model combined with fuzzy approximation error. The un-modeled dynamics are compensated using fractional order adaptive law which is derived using Lyapunov function. The validity and effectiveness of proposed control scheme are verified using numerical simulations.

A study of perturbations in linear and circular polarized antennas in close proximity to the human body and dielectric liquid filled rectangular and a cylindrical phantom at 1.8 GHz

In the design and synthesis of wearable antennas isolation distance from the body is a critical parameter. This paper deals with the comparison of perturbations caused to the matching of simple linear and circular polarized patch antennas due to the close proximity of a human torso and rectangular box and cylindrical phantoms filled with muscle simulating liquid at 1.8GHz. The isolated variable is return loss, S11(dB). Results show that at these frequencies a cylindrical phantom resembles the body more closely than a rectangular phantom.

Application of Pareto ranked genetic algorithm to a wearable ball spiral antenna

It has been demonstrated [2, 6] that a Pareto ranked genetic algorithm can be usefully applied to a printed wire Archimedean single arm spiral to obtain optimal results. Results presented at conference will optimize the novel ball spiral antenna using a GA with seven gene chromosomes and possible objectives of impedance −6dB bandwidth, good circular polarization over both hemispheres in close proximity to the human body and stable gain.

Triboelectric Nanogenerator Based Self-Powered Tilt Sensor

This work focuses on the fabrication and evaluation of triboelectric nanogenerator (TENG) based self-powered tilt sensor. The proposed fabricated structure is composed of polydimethylsiloxane (PDMS), steel ball, gold (Au) as electrode and circular ring housing. A specific configuration of electrodes was used to measure the tilt at different angles. FEM simulations were used to verify the electric potential at the electrodes at different angles. The outputs of the fabricated sensor were measured at different angles from 0 to 360°. A sensitivity of 254 mV/rad is obtained in single axis. The TENG based tilt sensor generates an open circuit voltage of 450 mV at 10 MΩ.

The effects of water on an on-body monopole diversity antenna pair at 1800MHz

This paper presents the effect of water on a pair of 1.8GHz on-body diversity monopole antennas mounted on the forearm of a sitting male static volunteer. Application of a water layer to the forearm was seen to both reduce efficiency and increase directivity leading to a slight overall increase in gain. Increased gain was shown to increase antenna correlation thereby reducing diversity gain in the antenna pair.