Publications Repository - Gdańsk University of Technology

This paper presents the design and validation of a slot-patch-hybrid circularly polarized antenna array for 28 GHz millimeter (mm) wave (mm-wave) applications. The proposed design has a simple geometry that facilitates the fabrication process, which is otherwise a challenging task due to the sub-mm dimensions of the circuit in the mm-wave band. In the proposed structure, aperture-coupled series slot-fed array is utilized to excite the 45-degrees inclined pair of patches. The feeding array aperture is designed by printing a straight microstrip feed line with a matching stub at the open end. Further, a coupling slot is etched underneath the feed line in the conventional horizontal position, and two vertical slots are merged toward each end of the slot. For realization of the series phased array of (1×(4×2)) elements, the slots are placed half guided wavelength away extending the array network along the feedline. A pair of the radiating patches are loaded on the top of the vertical slots. To ensure excitation of the 90-degree phase-shifted orthogonal field components of equal magnitude, the loaded patches are rotated by 45-degrees in the azimuth plane. The produced circularly polarized (CP) fields are further refined by an additional diagonal radiating slot etched in the middle of the pair of radiating patches parallel to the non-radiating edges. With the combination of radiating patches and the slots, a wide axial ratio bandwidth of 27.5 GHz to 28.5 GHz, broad impedance bandwidth, a highly directional beam, and a peak realized CP gain of 15.15dBic is achieved. For realizing omnidirectional radiation pattern necessary for the base station applications, 3-dimentional hexagonal/octagonal topology is utilized in six- and eight-antenna configurations. A detailed theoretical and numerical analysis and the corresponding results shows that the adjacent beams could be merged together constructively to form omnidirectional radiation patterns. The advantage of the proposed technique is the ease of implementation without affecting the major performance figures.

Authors

• Ullah Ubaid,
• prof. dr inż. Sławomir Kozieł link open in new tab ,
• dr hab. inż. Anna Pietrenko-Dąbrowska link open in new tab