A Wideband Antenna for mm-Wave Antenna-in-Package Application

Antenna-in-Package has been widely applied for millimeter-wave systems that integrate the MMIC chip and antenna into one package. For organic substrate Antenna-in-Package solutions, probe feeding and aperture-coupled feeding patches are generally used as radiation units. In this work, a patch antenna is proposed using coupled resonation; a wideband, high-gain and compact 3-D antenna package integration is realized. Equivalent circuit model is analysed for the coupled structure. $\boldsymbol {\lambda }\mathrm {/\mathbf {4}}$ coupled line is adopted for impedance matching, the whole antenna is designed on the same thick radiation patch substrate, with less organic substrate lamination layers. For millimeter-wave Antenna-in-Package structures, vias are generally used for vertical interconnections, which function well in the lower millimeter-wave frequency range. For operation frequency higher than 100 GHz, design difficulties may be encountered for via interconnection, with performance degeneration on impedance matching and transmission loss. In our work a H-shaped slot is integrated instead of vias on an organic substrate, realizing a high frequency and wideband mm-wave transition. An interconnection structure is also adopted to convert a microstrip line to differential microstrip line in the feeding network. Antenna prototype with $2\times 4$ radiation array is designed for verification purpose at 20 GHz frequency range with simulated bandwidth of 23%. The prototype is fabricated with separate PCB boards assembled with screws; measured antenna gain is 12.7 dBi - 13.5 dBi. The proposed structure provides a wideband and low-loss solution for potential higher frequency mm-wave Antenna-in-Package applications.