Compact Dual-Polarized Ultra-Wideband Cardioid Radiator with Matching Inserts

Introduction. In recent years, there has been a growing trend toward the miniaturization of printed radiators for phased arrays. At the same time, such radiators are frequently required to operate over an ultra wide bandwidth, support wide angle scanning, and enable dual polarization. To enhance the performance of printed radiators, matcing inserts with specific geometries and dimensions can be used.

Aim. To increase the overlap ratio of a printed radiator while maintaining its ultra wideband performance and wide-angle scanning within an angular sector of ±60º, limited by the mismatch, and ensuring electrical compactness with a height not exceeding λ at the upper operating frequency through the use of various matching metal inserts.
Materials and methods. Electrodynamic simulation of the radiator was performed as part of an infinite antenna array using the Ansys HFSS computer aided design software.
Results. The use of metal rectangular inserts measuring 25.5 × 145.0 mm at the edges of the radiator allowed its operating frequency band to be extended, while the use of an additional insert in the aperture allowed its matching (radiator with combined inserts) to be improved. The operating frequency band of the original radiator, at a voltage standing wave ratio (VSWR) of ≤ 3, extends from 257.6 to 732.5 MHz, corresponding to an overlap ratio of 2.844. For the radiator with combined inserts, the operating band at the same VSWR level ranges from 164.9 to 677.5 MHz, yielding an overlap ratio of 4.109. The electrical dimensions of the proposed radiator are 0.339λ × 0.339λ × 0.678λ at the upper operating frequency of 677.5 MHz, and 0.083λ × 0.083λ × 0.165λ at the lower frequency of 164.9 MHz.
Conclusion. The application of combined inserts in the radiator allows its overlap ratio to be increased at the same time as maintaining its ultra wideband performance, wide-angle scanning in the sector of angles up to ±60°, and compact dimensions. The proposed radiator can be used in phased arrays for radio communication, radar and radio navigation systems.

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