Millimeter-wave stepped series array with LTCC

The series fed antenna arrays are widely used to minimize the feeding losses. A novel method to control the coupling/admittance between the series array elements is studied. In this work, two substrate integrated waveguide (SIW) fed aperture coupled 1×4 patch arrays are designed on the LTCC platform. The admittance of the array elements are controlled with the stepped SIW and the non-uniform aperture coupling technique. The simulated and measured -10-dB impedance bandwidth of the designed antenna is approx. 6-7%. At 75 GHz, the maximum boresight directivity and realized gain of the designed antennas are 12 dB and 9 dBi, respectively. Additionally, a microstrip line (MSL)-SIW vertical transition structure is designed to facilitate the multi-layered RF structure in LTCC.