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Design of Robust Superdirective Receiving Antenna Array for Circular, Hexagonal and Elliptical Geometries

Nelakonda, Nikitha
http://rave.ohiolink.edu/etdc/view?acc_num=akron1460984746

Abstract Details

2016, Master of Science in Engineering, University of Akron, Electrical Engineering.
Superdirective beamforming deals with designing an antenna array that gives high gain, narrow radiation pattern and also cancels the signal in unwanted directions. It is not practically possible to achieve the same properties as an array antenna without use of an array; to do so would require a huge antenna that is too complex and expensive to be practical. Use of an array antenna induces a white noise gain into the output of an antenna array due to the mismatches between the antenna elements in an array. In optimum array gain method array gain optimization is considered as eigenvalue problem and antenna weights are the eigenvector of the largest eigenvalue. Optimum array gain method gives the maximum value of array gain and white noise gain which is not possible in practice, due to induced white noise gain. In this thesis, we present a design for a superdirective receiving circular antenna array. In the design process, complex (amplitude and phase) weights for each antenna element in the array are calculated in order to reduce white noise gain using a constraint for white noise gain depending on white noise gain from optimum array gain method. The output beam pattern of an array antenna is a function of the weights and antenna element positions. Beam patterns of each individual antenna element are multiplied by their respective complex weights and then summed together to give the output radiation pattern. Antenna arrays using the weights found with this design process have lower white noise gain than antennas designed using optimum array gain method. The circular antenna array has a drawback in that it has high side lobe levels in the radiation pattern. In order to design antennas with a more narrow radiation pattern, the design method is further extended to different antenna array geometries namely elliptical, concentric elliptical, cylindrical elliptical, hexagonal and concentric hexagonal array geometries. The array gain and white noise gain are calculated and the radiation patterns of these geometries are plotted using MATLAB. All these simulation results are compared with the optimum array gain method which does not consider white noise gain for calculation of antenna weights. Use of other geometries in place of circular array geometry has advantages like reduced side lobe level and increase of array gain considering same number of antenna elements in elliptical array compared to circular array. Then, simulation results for optimum array gain and constrained optimum array gain are generated at 60 GHz and 30 GHz frequency waves which are millimeter waves and results are compared and discussed with 30 MHz wave results. These results show that use of millimeter wave frequency reduces the size of the array antenna.
Hariharan S. I., Dr. (Advisor)
Arjuna Madanayake, Dr. (Committee Member)
Nghi Tran, Dr. (Committee Member)
Electrical Engineering
Antenna Arrays, Superdirective Antenna

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Citations

  • Nelakonda, N. (2016). Design of Robust Superdirective Receiving Antenna Array for Circular, Hexagonal and Elliptical Geometries [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1460984746

    APA Style (7th edition)

  • Nelakonda, Nikitha. Design of Robust Superdirective Receiving Antenna Array for Circular, Hexagonal and Elliptical Geometries. 2016. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1460984746.

    MLA Style (8th edition)

  • Nelakonda, Nikitha. "Design of Robust Superdirective Receiving Antenna Array for Circular, Hexagonal and Elliptical Geometries." Master's thesis, University of Akron, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1460984746

    Chicago Manual of Style (17th edition)

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