Loading...

Wideband Microwave Radio Direction Finding Based on Phase Interferometry Method for Two and Three Dimensional Arrays with Minimum Number of Antennas

Mollai, Sajjad | 2019

915 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 52216 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Farzaneh, Forouhar
  7. Abstract:
  8. The interferometer method, as one of the most accurate schemes for wideband direction finding (DF), is used. The interferometer method has various algorithms which can be implemented depending on the required specifications. The advantages and disadvantages of these algorithms have been evaluated and the appropriate algorithm for a general practical case in view of the ambiguity resolution is proposed. The receivers’ channel phase tracking error is of significant concern in practice, in interferometric DF systems. The induced error due to channels phase tracking error is estimated. Furthermore the use of physically realizable antennas, achievement of high accuracy, minimum number of antennas and consequently receivers and wideband DF is considered. The interferometric algorithms including Common Angle Search (CAS), Second Order Difference Array (SODA) and SODA-Based Inference (SBI) methods are compared for a linear array and the CAS method is selected as the appropriate algorithm. An optimized two dimensional cross form antenna array is devised by two orthogonal linear arrays. A cubic set for full coverage, has been proposed as the implementation of two dimensional wideband direction finding system with 〖360〗^° azimuth and ± 45° elevation coverage and its resolution in presence of additive noise and the channel phase tracking error is evaluated.In wideband interferometric direction finding ambiguity is inevitable due to practical antenna array dimensions. A new algorithm for wideband interferometer direction finding is developed to resolve the ambiguity problem with minimum number of antennas. The method is based on direction finding by three antennas arranged at the three vertices of a triangle, named the base-triangle. A two dimensional matrix of ambiguous angles is generated. The ambiguity problem is resolved by an auxiliary base-triangle formed by a fourth antenna in the arrangement. The common angle between the two ambiguous directions derived from the two base-triangles, is the desired angle of arrival. As such a four antenna array is optimized with the proposed algorithm to minimize the direction finding error through the 6GHz to18GHz frequency band for different signal to noise ratios and in the presence of channel phase tracking error. The array performance is evaluated through Monte-Carlo simulations for a coverage of ±45° azimuth and ±45° elevation and a polynomial expression is fitted to the evaluated Root Mean Square errors. Finally, a comparison is made between the proposed method and various correlative interferometer methods. The method has an accuracy better or equal to the cosine function correlative interferometer with much less computation time. Based on base-triangles and inspiring from one dimensional SODA and SBI methods, three new two dimensional algorithms are developed, which resolve ambiguity in wide frequency band with acceptable accuracy and much less computation time
  9. Keywords:
  10. Phase Comparison Direction Finding ; Wide Band Direction Finding ; Two Dimensional Direction Finding ; Phase Interferometer Algorithm ; Base Triangle ; Log-Spiral Antenna ; Planar Antenna Array ; Cross Form Array ; Microwave

 Digital Object List

 Bookmark

No TOC