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Microstrip patch antennas are the most common type of printed antenna due to a myriad of advantages which encourage use in a wide range of applications such as: wireless communication, radar, satellites, remote sensing, and biomedicine. An initial design for a stacked-patch, broadband, dual-polarized, aperture-fed antenna is tested, and some adjustments are made to improve performance. The design goal is to obtain a 3 GHz bandwidth centered at 10 GHz for each polarization. Once the single-element design is finalized, it is used in a 4x1 array configuration. An array increases the gain, and by utilizing variable phase-shifters to each element, the pattern can be electronically steered in a desired direction. The phase-can be easily adjusted. The result of this new phased array design is a wide bandwidth system with dual-polarization which can be electronically steered. Rectennas (rectifying antennas) are used in wireless power transmission (WPT) systems to collect microwave power and convert this power into useable DC power. They find use in many areas such as space power transmission, RFID tags, wireless sensors, and recycling ambient microwave energy. The ability to simulate rectenna designs will allow for an easier method of analysis and tuning without the time and expense of repetitive fabrication and measurement. The most difficult part of rectenna simulation is a good diode model, and since different diodes have dissimilar properties, a model must be specific to a particular diode. Therefore, a method of modeling an individual diode is the most critical part of rectenna simulation. A diode modeling method which is based on an equivalent circuit and compatible with harmonic balance simulation is developed and presented. The equivalent circuit parameters are determined from a series of S-parameter measurements, and the final model demonstrates S-parameters in agreement with the measured data. An aperture-coupled, high-gain, single-patch rectenna is also designed and measured. This rectenna is modeled using the presented method, and the simulation shows good agreement with the measured results. This further validates the proposed modeling technique.

In high voltage direct current power transmission, the need to filter the non-sinusoidal current wave forms drawn by the converters from the ac supply has long been acknowledged. Assessment of the harmonic content of these waveforms to the best accuracy possible is a desirable objective to aid filter design. The conventional analytical technique necessitates making simplifying assumptions and produces only approximate results. Such practical considerations as system unbalance cannot be taken into account. The objective of the research was to perform in-depth analyses of hvdc transmission links, by developing a mathematical model which, in addition to perfectly balanced conditions, allows for the following practical operational abnormalities: (i) Unbalanced 3-phase ac supply voltages (ii) Unbalanced converter transformer impedances (iii) Asymmetrical thyristor valve triggering, whilst not making the usual assumptions of infinite dc side inductance and zero ac system impedance. In other words to develop a completely comprehensive mathematical model. The initial approach was to develop the tensor analysis of a six-pulse Graetz bridge supplied first by a star-star, and then by a star-delta connected transformer. A twelve-pulse converter system was then investigated by modelling the series connection of these two arrangements. The technique of diakoptlcs was introduced and combined with the previous tensor analysis to model a complete dc link with a twelve pulse converter at each end of a transmission line. The diakoptic approach enables the full circuit to be torn, for the purpose of the analysis, into the two twelve pulse converters and the dc line. Summary The final stage of the development of the model involved the inclusion of a more sophisticated representation of the ac system impedance and the addition of tuned or damped filters at the ac busbars. To verify the program, computed results from the mathematical model are compared with corresponding experimental results obtained from a laboratory-scale model of a typical hvdc link configuration. Comparisons are also made with conventionally based calculations involving the assumptions included in the computer-based results, in order to investigate the relative accuracy of the computed solution.

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