A balanced-fed 45° linearly polarized slot array antenna using SIW technology

A 45° linearly polarized slot array antenna with balanced feeding network is proposed in this paper for automotive radar applications. The radiation element consists of one 45° inclined slot and two reflection cancellation vias. The balanced meandering feeding network proposed in this paper is able to achieve a relatively wide impedance bandwidth resulting from the traveling-wave propagation. In addition, it can obtain a wide gain bandwidth and a stable broadside radiation as the standing-wave array antennas do. A prototype array antenna with 4 radiation elements is designed and fabricated at 24 GHz to validate the proposed design. The experimental results agree well with simulation predictions. The prototype array antenna can properly work from 23.9 GHz to 25.0 GHz (4.5 %) with its reflection coefficient under -10 dB. Besides, the gain bandwidth of the prototype antenna is 23.9 GHz- 25 GHz (4.5 %) with the gain dropped by 1 dB. The maximum gain of the prototype array is around 10.81 dBi at 24.7 GHz.