A Beam-Shaping Feeding Network in Series Configuration for Antenna Array With Cosecant-Square Pattern and Low Sidelobes

An SIW feeding network is proposed to achieve a cosecant-square beam pattern with low sidelobes. Different from conventional feeding networks in parallel configuration to obtain such a beam pattern, the proposed structure is in series configuration, which can provide higher transmission efficiency. Moreover, power-dividers within this feeding network can provide larger power-division ratio than conventional designs, enabling low-sidelobe levels. Vertical decoupling walls are also utilized for the acceleration of the whole design procedure. A 15 × 22 array prototype operating at
Ku
-band, which requires cosecant-square radiation pattern for the elevation plane and pencil-beam radiation pattern for the azimuth plane, is designed and fabricated. Measured results show that, within the target frequency range (15 GHz–16 GHz), the achieved maximum gain is larger than 27.4 dBi with sidelobe levels (SLLs) lower than 20 dB for both the elevation and azimuth planes. The excellent performance indicates that the overall design approach is very suitable for such kind of large scale antenna arrays.