Compact Scalable Gap Waveguide Phased Array Horn Antenna with Efficient Decoupling Network

A compact scalable gap waveguide (GW) phased array horn antenna with efficient decoupling network (DN) is proposed. An H-plane GW horn antenna with transverse slots-based slow-wave (SW) structures is designed as the array element. By compensating the phase error along the horn aperture, the antenna length is greatly reduced while the gain is enhanced. To suppress the strong mutual coupling between adjacent elements due to the small spacing, an efficient DN is proposed by introducing a through slot inside the intermediate sidewall between adjacent antenna elements. With this DN, an extra wideband equal-magnitude and anti-phase signal can be generated to cancel the coupling signals. Based on the contactless characteristic of the GW, the presented antenna can be extended to large-scale arrays with high reliability. An 8-element phased array antenna operating at 24-30 GHz is implemented for verification. The antenna length is reduced by 62.2% compared with the optimum horn antenna, and the mutual coupling is reduced by up to 32.7 dB with the DN. The measured array gain is higher than 19.8 dBi and the scan angle reaches ±60° with a scan loss of less than 4.5 dB.