A long slot array fed by a multilayer true-time delay network in LTCC for 60-GHz communications

A broadband array of four long slots, a non-dispersive corporate feeding network and a pillbox beamformer are integrated in a multilayer low temperature co-fired ceramic (LTCC) module for millimeter-wave (mm-wave) wireless communications. The novel concept of substrate integrated parallel plate waveguide (SI-PPW) is demonstrated. It allows transverse electromagnetic (TEM) modes to propagate along the vertical axis of the module. The slot array is loaded by a matching layer and optimized for wideband operation. An advanced LTCC process is tailored to implement a true-time feeding network in SI-PPWs. The measured -10 dB matching bandwidth ranges from 51.2 GHz to 66 GHz. Simulated radiation patterns in H-plane exhibit stable properties in the 57-66 GHz band, with side-lobe levels (SLLs) lower than -19 dB. The peak directivity is 17.90 dBi at 64 GHz. This design concept and the proposed technology are suitable for mm-wave systems-in-package, with applications to high-speed wireless networks.