Increasing Operating Range of Wideband Reconnaissance Receivers, by Using Antenna Arrays

Sobhani, Ghasem | 2022

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 55109 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Behnia, Fereidoon
  7. Abstract:
  8. Passive wideband reconnaissance receivers, listen to the radio and radar signals in the environment and estimate their important parameters such as direction of arrival (DOA). The wideband attribute for these receivers is to refer to their ability to receive wideband signals.Due to the use of processing gain, LPI radars reduce their transmitted signal power to see and not to be seen. On the other hand reconnaissance receivers can not have much processing gain, because they do not know the nature of the transmitted signal; Therefore, to increase the operational range of these systems, it is necessary to increase the signal to noise power ratio (SNR). This thesis examines the use of antenna arrays and beamforming to increase the input signal gain in direction finding systems. Also, since the signal DOA is the most important parameter for radar reconnaissance receivers, this thesis uses phase interferometric algorithm for high accuracy direction finding (DF).In this thesis, which consists of two parts, the use of antenna arrays and interferometry DF are the common part of both parts. Focus of the first part of the thesis, is on analog beamforming; so that while the number of antennas increases, the number of receivers is not increased. Also to add beamforming to the direction finder, the antennas placement is studied and two types of placements, named “Concentric Antenna Pairs” and “Basis Pattern Repetition”, are introduced. In the second part of the thesis, all antennas are assumed to have their own separate receiver, so that every processing can be done in the digital domain and with better quality. In this case, the main problem is the large number of receivers, and we have tried to reduce the volume and cost of these receivers by sub-Nyquist sampling. To implement sub-Nyquist sampling and phase interferometry jointly, the signal of each antenna is sampled with a different rate. The proposed receiver with the simple implementation has a good performance in terms of frequency channel detection, ability to receive simultaneous narrow-band and or wide-band signals and extracting internal information, compared to the existing methods
  9. Keywords:
  10. Reconnaissance Receiver ; Direction Finding ; Sub-Nyquist Sampling ; Beamforming ; Phase Interferometer Algorithm ; Direction of Arrival (DOA) Algorithms

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