DSDS 16

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https://dspace.lib.cranfield.ac.uk/handle/1826/21504

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Browsing DSDS 16 by Subject "'Antennas and Propagation'"

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    Baseband version of the bat-inspired spectrogram correlation and transformation receiver
    (Cranfield University, 2016-12-06 14:47) Georgiev, Krasin
    Poster presentation at the 2016 Defence and Security Doctoral Symposium. Echolocating bats have evolved an excellent ability to detect, resolve and discriminate targets in highly challenging environments. They have had more than 50 million years of evolution to optimise their echolocation system and behavioural experiments have shown their exceptional ability to detect and classify targets even in highly cluttered surroundings. Behavioural experiments have demonstrated that bats are able to resolve closely located scatterers: •a two-point resolution of 2÷10 μs with waveforms of a bandwidth of 85 kHz (Eptesicus fuscus) • discriminate between two phantom target echoes separated by a time-delay of about 1  μs with waveforms of a bandwidth of up to 100 kHz (Megaderma lyra) •higher range resolution performance with respect to the conventional matched filter. The way bats process target echoes is different from the standard processing techniques used in radar and sonar, and there may be lessons to learn by investigating differences and similarities. The Spectrogram Correlation And Transformation receiver (SCAT) is an existing model of the bat auditory system that takes into account the physiology and underlying neural organisation in bats that emit chirped signals. The aims of this work are: •develop a baseband receiver equivalent to the SCAT to    - allow the application of biologically inspired signal processing to radar baseband signals  - enable further theoretical analysis of the key concepts, advantages and limitations of the “bat signal processing” •carry out simulations and experimen ts to investigate differences and similarities between the output (the frequency interference pattern for two closely located scatterers) of the original SCAT and that of the proposed baseband version.
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    Beampattern and Polarisation Synthesis of 3D RF-seeker Antenna Arrays
    (Cranfield University, 2017-01-12 09:50) Fourtinon, Luc
    Poster presentation at the 2016 Defence and Security Doctoral Symposium.Existing missile radar seekers use a mechanical rotating antenna to steer the radiating beam in the direction of the target. Recent research is investigating the possibility to replace the mechanical RF seeker with a novel 3D conformal antenna, embedded below the radome, that can steer the beam electronically. 3D conformal antenna arrays may offer many advantages, such as a higher gain and an extended coverage, and new degrees of freedom which derive from the resulting higher flexibility in the choice of the 3D shape. Despite this, they also present new technical challenges, related to the robustness of the beampattern characteristics as a function of the steering angle, that must be addressed. The overall objective of our research is to design, prototype and assess the performance of novel 3D conformal antenna arrays for RF seekers. In order to do this, a first study has been carried out to generate and display the polarisation pattern of any 3D antenna arrays. In this paper, we present an electromagnetic antenna tool that has been developed to carry out an analysis of  beamforming and polarisation for any shape of 3D antennas. The program imports the pattern of an individual element of the array and generates the global radiation pattern by coherently summing the contribution of each element. One feature of the tool is the calculation of the polarisation pattern induced by the conformation which provides a complete description of the time varying electric field of the array.
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    Multi-Function RF Seeker Based on 3D Phased Array
    (Cranfield University, 2017-01-11 14:33) Kocjancic, Leon
    3MT presentation at the 2016 Defence and Security Doctoral Symposium.Current RF seekers in use today have mechanical steerable antennas. In order to reduce the cost of the mechanical system and to significantly improve the performance of the missile seeker, the electrically controlled 3D antenna array is proposed. Given solution will result in a much more robust antenna which will be capable of steering much faster and more accurately than existing solutions. Furthermore, the proposed antenna will provide an increased coverage and dwell time as a result of flexible beam steering. Additional degrees of freedom will allow it to carry out multiple tasks.The main aim of proposed PhD is to investigate theoretical background and realization of multiple beams that will conduct different tasks, such as radio-altimetry, target seeking, proximity activation and radar imaging. By using 3D antenna as a co-located multiple-input multiple-output system and by using suitable orthogonal waveforms the novel seeker will be capable of generating multiple beams.