Synthesis of Cosecant-Squared Pattern With a Compact Linear Array Using the Extended Method of Maximum Power Transmission Efficiency

The conventional sector beam antenna array used in communication system suffers from the reduced signal strength as its distance to the receiving terminal gradually increases. In response to this challenge, a compact 18-element linear antenna array with cosecant-squared pattern is proposed and designed by the extended method of maximum power transmission efficiency in this letter. By setting the appropriate weights for the radiated field at varying distances, the shaped field pattern within the desired angular coverage aligns with the desired cosecant-squared distribution. The sidelobe levels are suppressed by introducing smaller weights for the regions outside the main beam. To reduce the antenna array size, the inter-element spacing of the array antenna is set as 0.35λ₀. Experimental results indicate that the maximum deviation between the measured field pattern and the desired cosecant-squared curve is only 0.9 dB, while achieving a sidelobe level below −20 dB simultaneously.