A 79-GHz LTCC Patch Array Antenna Using a Laminated Waveguide-Based Vertical Parallel Feed

A microstrip patch array antenna based on a low-temperature co-fired ceramics (LTCC) technology is presented in this letter. The antenna is designed for the 77-81-GHz radar frequency band and uses a high-permittivity material (ε
_r
= 7.3). A laminated waveguide (LWG) was chosen as transmission line, which minimizes coupling and enables the design of LWG-based vertical power dividers. Three stages of power dividers were combined to realize a vertical parallel feeding network. With this feeding-network, the radiation pattern of the proposed antenna is nearly constant across the whole 4-GHz bandwidth. A uniform aperture distribution was chosen. In total, 12 layers of LTCC tapes were used. The measured half-power beamwidth in the E-plane is ≤ 7° across the whole working frequency bandwidth. This compact LTCC antenna (28.3 × 1.2 mm
²
) is suitable for short/middle-range radar applications, especially for those with a small channel spacing requirement .