E.A. Elkhazmi

A power and efficiency measurement technique for active patch antennas

In this paper, the power input to the radiating element of an active microstrip patch antenna is measured using a small sensing patch, which is weakly coupled to a radiating edge. Combined with an estimate of patch radiation efficiency, this also yields a measurement of total radiated power. The method has advantages of convenience, insensitivity to room reflections, and a weakly frequency-dependent calibration factor.

Compact Dual-band Balanced Handset Antenna for WLAN Application

In this paper, a balanced antenna for mobile handset applications with dual- frequency performance, covering the 2.4GHz and the entire 5GHz WLAN frequency bands, is investigated and discussed. The antenna is a thin-strip planar dipole with folded structure and a dual-arm on each monopole. For validation, the antenna prototype was fabricated and tested. The performance of this balanced antenna was verifled and characterised in terms of the antenna return loss, radiation pattern, power gain and surface current distribution of the proposed antenna. The predicted and measured results show good agreement.

Shaping Technique of an Active Patch Antenna for Harmonic Radiation Control

A shaping technique for the radiator of an active patch antenna is described, and shown experimentally to reduce harmonic radiation and therefore enhances the conversion efficiency. The perturbation of resonant mode frequencies in a deformed rectangular patch radiator is discussed as a possible basis for systematic design. Various techniques of plotting results were employed for maximum understanding

Harmonic impedance and radiation control for an active patch antenna

A shaping technique for the radiator of an active patch antenna is described, and shown experimentally to reduce harmonic radiation, the result is increased conversion efficiency. The perturbation of resonant mode frequencies in a deformed rectangular patch radiator is discussed as a possible basis for systematic design.

Indoor localization using received signal strength

A comparison between two indoor localization algorithms using received signal strength is carried out. The first algorithm is the vector algorithm; the second is the matrix algorithm. The comparison considered the effects of the reference points, the access point, and the frequency on the accuracy of the localization process. The experiments were carried out using ray tracing software and MATLAB. This paper justifies the use of adopting the matrix algorithm.

Experimental and theoretical investigation of high efficiency active patch antennas

A new shape has been proposed for a micro-strip radiator which showed an improvement in the power added efficiency when integrated with a medium power transistor. The new shape produced little or no improvement when tried in a class F amplifier arrangement. Initial investigation implied that class F amplifier is problematic when it is tried with medium-large transistors.

Discrete-wavelet transform modulation over Multiple Input Multiple Output applications

Discrete wavelet transform (DWT) for Multiple Input Multiple Outputs (MIMO) bandlimited systems is investigated. The implementation involves using the DWT as the base multiplexing technology at the baseband to process the input signal. Using the Alamouti diversity technique, an investigation for a DWT-MIMO multicarrier system is presented. Results shown are quite interesting; however these were very consistent with the earlier discussion presented in the original Alamouti work. The scheme is however implemented for DWT-MIMO case wherein more receiver diversity is of stern interest. Our implementation in favour to cover 2 xNr MIMO systems (Nr is the number of receivers elements).

Simplified waveform measurement in a microwave power amplifier

Voltage and current time waveforms in a microstrip-based microwave power amplifier are measured using capacitive and inductive probes with a small spatial extent and essentially pure response to voltage and current. Their transfer functions are inverted by elementary analogue filtering of waveforms scaled to low frequency by a sampling oscilloscope.

Performance of different wavelet families using DWT and DWPT-channel equalization using ZF and MMSE

We have studied the performance of multidimensional signaling techniques using wavelets based modulation within an orthogonally multiplexed communication system. The discrete wavelets transform and wavelet packet modulation techniques have been studied using Daubechies 2 and 8, Biothogonal1.5 and 3.1 and reverse Biorthognal 1.5 and 3.1 wavelets in the presence of Rayleigh multipath fading channels with AWGN. Results showed that DWT based systems outperform WPM systems both in terms of BER vs. SNR performance as well as processing. The performances of two different equalizations techniques, namely zero forcing (ZF) and minimum mean square error (MMSE), were also compared using DWT. When the channel is modeled using Rayleigh multipath fading, AWGN and ISI both techniques yield similar performance.

Direct determination of PE and PAE of an Active patch antenna

In this paper, the power added efficiency and/or the power efficiency of an active antenna was measured using a specially devised setup. This was based on previous work by the authors whereby the power input to a radiating element of an active patch antenna was measured using a small sensing patch. Combined with an estimate of patch radiation efficiency, the method also yields a measurement of total radiated power. Because of weakly frequency-dependant calibration factor, the method has advantages of convenience and can be integrated with modern computer based measurement systems.