Wideband Endfire Antenna Array for Future Short-Range Communications

Abstract

A broadband, unidirectional, phased array is proposed. Single antenna element of the prototyped array is a broadband windmill-like shaped antenna. Four elements of this antenna are fed by a power divider and are configured in a novel semicircular-shaped, angular-phased array. A phase difference of $\pi $ /4 was introduced by optimizing the angular path difference among four antenna elements in the array. Total 21.5% of size reduction is achieved by introducing angular-phased array in comparison with the conventional linear-phased array. The array of radius 65 mm is prototyped on the Rogers RO4232 substrate for the operating frequency range 9.35–42.89 GHz. The proposed array configuration can maintain an average gain of 8.54 dB and average radiation efficiency of 69.71% in the entire operating frequency range while exhibiting a peak gain of 11.86 dB. The presented array exhibits highly directional behavior in the endfire direction, with the 3-dB angular beamwidth in the range from 15.1° to 76.7°. To the best of the authors’ knowledge, any comparable state-of-art has not been reported yet in the literature that could provide such a large impedance bandwidth in sub-mmWave range. The proposed array may find its applications for future indoor and outdoor short-range communication networks.