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.