A Low-Profile Antenna with Forward and Backward Broadband Wide-Angle Cosecant-Squared Radiation Pattern

In this letter, a printed-dipole array antenna with a broadband wide-angle cosecant-squared radiation pattern in both forward and backward directions is developed. A novel beamforming method employs only two dipoles to achieve the wide-angle cosecant-squared radiation pattern. By adjusting the distance between dipoles, the phase difference between dipoles can be adjusted to a proper value to achieve beamforming. Then, a novel principle is proposed to restrain fluctuation in the radiation pattern and maintain pattern stability. Based on the proposed principle, two dipole pairs (four dipoles in total) are designed to generate a preferable cosecant-squared radiation pattern across different operation bands. The cooperation of dipole pairs allows them to compensate for each other's fluctuations in radiation patterns, which enhances the pattern stability bandwidth. The fabricated prototype is measured and the measured results agree well with the simulated results, showing that the proposed antenna achieves a forward and backward wide-angle cosecant-squared radiation pattern from 5.5 GHz to 6.7 GHz. The measured gain ranges from 5.3dBi to 6.1dBi, with a total efficiency exceeding 80% across the operation band.