Development of an ultra wide band (UWB) array antenna

2022-4
Ceylan, Hasan Akın
Demand for ultrawideband antenna arrays in telecommunications, space and airborne platforms, RADAR applications and MIMO systems, etc. is rising consistantly. A modern approach to develop an ultrawideband array is to utilize the mutual coupling between array elements. Even though individual elements are of narrowband characteristic in isolated form, they gain ultrawideband performance in array configuration under strong mutual coupling. In this work, an ultrawideband tightly coupled dipole array antenna is designed, fabricated and measured. Overlapping dipole arms is utilized as the tight coupling scheme. Infinite array of proposed TCDA has the bandwidth from 0.9 GHz to 6.8 GHz for VSWR<3.1 condition. For the unit cell of the infinite TCDA, gain varies from -11.1 dBi to 12.8 dBi with respect to frequency. The Klopfenstein tapered line balun and impedance transformer are inserted to feed the infinite array, yielding BW from 1.28 to 6.12 GHz for VSWR<3.1 condition, while having several extremely narrowband common mode VSWR spikes occuring in the band. In order to prove the concept, the TCDA is fabricated with 5×5 configuration, on RO4350b with 0.762 mm thickness with 0.035 mm copper. The ground plane is fabricated with FR4 core material of 1.5 mm thickness. The fabricated TCDA is measured with left-open elements, i.e. active element measurements with unterminated v elements. As the measurement results, the center element of the array has a bandwidth from 2.67 GHz to 6.8 GHz for VSWR<3.1 excluding small peak at VSWR in 3.15 to 3.3 GHz. 5×5 array has a secondary operational BW from 7.73 GHz to 20 GHz for VSWR<3.1. The measured gain of center element varies from -3.75 dBi to 8.36 dBi in 3 to 12 GHz measurement in unechoic chamber. 9 elements of the 25 total are measured, array patterns are synthesized via MATLAB using the 9 measured elements.

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Citation Formats
H. A. Ceylan, “Development of an ultra wide band (UWB) array antenna,” M.S. - Master of Science, Middle East Technical University, 2022.