Millimetre-wave slotted array antenna based on double-layer substrate integrated waveguide

In this study, a millimetre-wave slotted array antenna based on double-layer substrate integrated waveguide (SIW) is proposed. The radiating array and feeding network are arranged on different substrate layers with a normal printed circuit board process. The design procedure of radiating elements based on array parameters extraction is introduced. A broadband T-junction and tilted coupling slots are used for power division in feeding network. A broadband right-angle transition between SIW and standard rectangular waveguide WR28 is designed and integrated in the bottom metallic plate for measurement. An 8 × 8 array operating at 35 GHz is designed and fabricated. Measured gain is 19.94 dB with sidelobe suppression of -19.8 dB in the E-plane and -17.7 dB in the H-plane at the centre frequency. The measured bandwidth of 20 dB return loss is 1.32 GHz. The good agreements between simulations and experiments demonstrate that the proposed double-layer SIW slotted array antenna is a good choice for un-rectangular aperture array and large array applications.