A new LADAR prototype system has been designed and implemented to be able to capture the 3D LADAR data from the surfaces of various objects. This system is designed to have a high technical specification and recognition ability through the using of new LADAR image descriptors. These descriptors are arise from the chromatic methodology to extract features from the LADAR images by applying new types of processors called invariant spatial chromatic processors. This represents the first step towards using this methodology for processing LADAR images. The descriptors are developed to have high discrimination ability, robust to the effects that disturb LADAR images, and required less storage space and computational time for recognition. The performance of the proposed LADAR descriptors were first evaluated using simulated LADAR images, which are generated from special software called LADAR simulator. This software has been written to produce simulated LADAR images under a wide variety of conditions. It models each stage from the laser source to the data generation and using proposed approach to be able to deal with complex models and produces high resolution image with short execution times. Experimental tests are also being undertaken on the new designed LADAR system in order to asses its ability to provides 3D images and its recognition performance with the proposed descriptors. The simulation results show high discrimination ability for the new descriptors over the traditional techniques such as Moments descriptor, which is also used to benchmark the results. The results also show the robustness of the proposed descriptors in the presence of noise, low resolution, view change, rotation, translation, and scaling effects. The experimental results show the effectiveness of the LADAR system and its ability to scan different objects and produce their 3D images with different scanning parameters. The results also show high recognition performance for this systems when using the new LADAR descriptors compared to using Moments descriptor under the same variety of scanning condition.

Ground Penetrating Radar (GPR) is an active and non-invasive exploration technique based on the propagation of electromagnetic waves in the subsurface. Developing new and simple algorithms to improve the GPR performance is important because it helps to interpret the data received by the GPR. This leads to the basis (solution to the forward problem) for most iterative inversion techniques. Conversely, imaging is a type of inversion technique (backward propagation) that creates an image related to the subsurface reflectivity. However, for practical applications, imaging techniques must be fast, accurate and efficient.

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This thesis studies the long term variation of the high latitude ionosphere and its activity. A statistical analysis of backscatter data spanning 20 years from 1996 to 2015 in the total field of view of the two HF radars was carried out in order to determine the solar cycle, the annual and the diurnal variations of backscatter (ionospheric scatter and ground scatter) in both Super Dual Auroral Radar Network (SuperDARN) radars over a longer time period. Increase in ionospheric scatter during solar maximum previously anticipated by Milan et al., (1997b) and higher occurrence of ground scatter than ionospheric scatter were observed in the analysis. The study in this thesis also includes investigation on the propagation mode responsible for the occurrence of ionospheric and ground backscatter. Similar to the data used in the first analysis, 20 years of data from three selected beams were employed. In this study, it was found that occurrence of ionospheric backscatter is prominent at far ranges at local day during solar cycle 23 than solar cycle 24. The analysis shows that occurrence of ionospheric scatter is seen at mid-range gates during summer in contrast to similar study carried out by Milan et al.(1997b) which identifies near range gates ionospheric scatter during similar period. In addition, a study to identify the parameter or parameters that can be used for adequate prediction and forecast of occurrence of ionospheric backscatter for both short and long term durations was carried out. The percentage occurrence of ionospheric scatter as a function of the selected parameters in spring, summer, autumn and winter from January 1996 to January 2016 in the four magnetic local times were analysed. The study increases our understanding on the global factors responsible for the occurrence of ionospheric scatter and the local time variation on the occurrence rate. It also raises some interesting questions.

The exploitation of synthetic aperture radar (SAR) data for remote sensing and intelligence gathering purposes over complex terrains (such as urban areas) is a relatively immature subject. In this thesis, the detection and recognition of targets of military interest within urban areas is addressed. Such 'hard targets' may be vehicles or particular manmade structures within a scene (as opposed to geographical features or flora). Those techniques investigated can be divided into three areas building height extraction, urban SAR exploitation and polarimetric assisted target recognition. Theoretical performance limitations of interferometric SAR and shadow/layover analysis for building height extraction were derived and validated using example airborne data. Techniques to assist analysts exploit SAR data over urban areas were developed and demonstrated. A post image formation matched filter enabled scatterers with non uniform frequency and aspect angle responses to be categorised in wide bandwidth SAR imagery. Sub-aperture movies allowed the velocity of a moving target and the structure of a building's roof to be determined. The direction of multipath responses in squinted SAR was characterised. Additionally, modelling software enabled an assessment of the impact of radar shadowing on urban exploitation as a function of collection geometry, radar mode and terrain type. Polarimetric features were shown to aid the task of target recognition and temporal and between class stabilities were quantified using example inverse SAR turntable imagery. To polarimetrically calibrate this data, a generalised distortion model was derived together with the development and demonstration of a Fourier method for the determination of calibration parameters using a rotating dihedral.

The pointing accuracy of the tracking antenna used in a radar guided homing missile is reduced by a streamlined radome. This can have serious effects on the missile's performance. The pointing error of a microwave antenna inside a radome can be predicted with fair accuracy provided that the radome and antenna diameters are ten or more wavelengths. This is done, basically, by determining the modified aperture distribution, taking account of the varying phase shift through different parts of the radome. The polar diagram of the modified aperture distribution is then calculated. If the radome diameter is only about five wavelengths this procedure (the 'insertion diffraction theory') is not usually adequate. The pointing error can be calculated from known aperture fields, under reasonable conditions, for small antennas. The inadequacy of the theory is therefore mainly due to the inability to calculate the aperture fields with sufficient accuracy. The reasons for the failure of the ray tracing procedure are discussed and it is shown that scattering by the tip of the radome, surface waves guided by the radome and multiple scattering (interaction) between the antenna and the radome would be expected to modify the aperture fields and introduce pointing errors. The propagation of surface waves on radomes is investigated and a calculation of the pointing error due to the surface wave is carried out. Experiments showed that surface waves can be troublesome on a very lossy radome but for the small ceramic radomes used in this research they are not significant. A method is described for calculating the pointing error caused by interaction between an antenna and an infinite plane dielectric sheet of uniform thickness. This method is not generally applicable to radomes and a method for radomes is developed. It is found that interaction is a serious cause of error, especially if the radome has a low dielectric constant. The tip scattering effect is also found to give large pointing errors in small radomes. The effect of radome diameter (measured in wavelengths) on each of the sources of error is examined and it is shown that, whereas the pointing error due to phase variation effects is inversely proportional to size, the errors due to the other effects vary much more rapidly. This explains why the latter are only of second order importance in large radomes but become predominant in small ones. It is shown that a high dielectric constant is essential for small radomes which are to be used over a narrow frequency band.

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