Browsing by Author "Mungara, Nagarakshith R."

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    CFAR detection in heterogeneous K- distributed sea-clutter background
    (Cranfield University Defence and Security, 2024-11-13) Mungara, Nagarakshith R.; Balleri, Alessio
    Detection of targets at sea is challenging due to unwanted echo returns from the sea surface, i.e. sea clutter returns. To account for the undesired effects of sea clutter at the receiver, and to control the probability of detection and false alarm, the K-distribution has often been used to provide a promising statistical fit to real clutter data. However, controlling the performance of the receiver becomes very challenging in heterogeneous clutter, that is when there is a sudden transition from one clutter region to another with a change in shape and/or scale distribution parameters. A possible solution to this challenge is to use some prior information on the sea clutter characteristics to generate clutter maps that inform adaptive detection solutions. This prior information can be obtained by the radar in real time (or close to real time) using oceanographic models, statistical clustering or potentially Artificial Intelligence.This research presents our first step in this direction by investigating detection in heterogeneous fully correlated K-distributed sea clutter. A transition line between homogeneous clutter regions is estimated using the statistical parameters of a K-distribution, to avoid polluting the training windows of a Constant False Alarm Rate (CFAR) detector with non-representative data. The transition cells assist to resolve the heterogeneous clutter into small homogeneous clutter regions and for every homogeneous region a CFAR detector is designed according to the K-distribution shape parameter. Results are obtained and presented for simulated data as well as for real sea clutter data provided by Hensoldt UK.
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    ItemOpen Access
    CFAR detection in heterogeneous K-distributed sea-clutter background
    (IEEE, 2024-10-21) Mungara, Nagarakshith R.; Balleri, Alessio; Kocjancic, Leon; Acland, Tim
    Detection of targets at sea is challenging due to unwanted echo returns from the sea surface, i.e. sea clutter returns. To account for the undesired effects due to sea clutter at the receiver, and to control the probability of detection and false alarm, the K-distribution has often been used to provide a promising statistical fit to real clutter data. However, controlling the performance of the receiver becomes very complicated in heterogeneous clutter, that is when there is a sudden transition from one clutter region to another with a change in shape and/or scale distribution parameters. A possible solution to this is to use some prior information on the sea clutter characteristics to generate clutter maps that inform adaptive detection solutions. This prior information can be obtained by the radar in real time (or close to real time) using oceanographic models, statistical clustering, or potentially Artificial Intelligence.This paper presents our first step in this direction by investigating detection in heterogeneous fully correlated K-distributed sea clutter. A transition line between homogeneous clutter regions is estimated using the statistical parameters of the K-distribution, to avoid polluting the training windows of a Constant False Alarm Rate (CFAR) detector with non-representative data. The transition cells assist to resolve the heterogeneous clutter into small homogeneous clutter regions and for every homogeneous region a CFAR detector is designed according to the K-distribution shape parameter. Results are obtained and presented for simulated data as well as for real sea clutter data provided by Hensoldt UK.
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    ItemOpen Access
    Design of super wide band 3‐way power divider/combiner
    (Institution of Engineering and Technology (IET), 2024-11) Mungara, Nagarakshith R.; Ray, Kamla Prasan
    A 1:3‐way power divider/combiner has been proposed for much improved bandwidth and isolation between output ports. The matching network for the super wide bandwidth frequency range is designed using a combination of the Klopfenstein taper and the triangular taper. The proposed design yields bandwidth from 1.5 to 20 GHz (18.5 GHz) for return loss better than 15 dB and isolation better than 20 dB. The insertion loss for the entire frequency band is 0.8 dB which is only 0.34 dB for the ultra‐wide bandwidth (3.1–10.6 GHz). The maximum phase imbalance of 3.32° and amplitude imbalance of 0.199 dB between all the output ports have been achieved over the entire bandwidth. The simulated results have been validated experimentally.