Ultrawideband Filtering Phased Array Antenna Based on Multilayer PCB and BGA-Via for AESA Vertical Heterogeneous Integration

In this article, an ultrawideband (UWB) filtering phased array antenna is proposed based on the tightly coupled dipole concept by introducing short-terminal vias and open-terminal vias in the radiation unit cells. The short-terminal vias and the open-terminal vias contribute to the low and high radiation nulls, respectively, which are also evaluated simply. Then, a vertical integrated Marchand balun is applied to feed the coupled dipole and the short-terminal vias are combined as its ground via array. Thus, the proposed UWB filtering phased array antenna can be designed using the multilayer printed circuit broad (PCB) with low profile. To achieve a large ratio between via height and via diameter, the BGA-via technique is also used for the phased array antenna design. Then, the active reflection coefficients are simulated and the resonances within its operating band are analyzed for $\theta =60^{\circ }$ scan in the E-plane and H-plane. Finally, a phased array antenna prototype is fabricated and assembled to demonstrate the designed performances, including active voltage standing wave ratio (VSWR), antenna gain, and antenna patterns from 5 to 15.5 GHz. About 15-dB radiation suppression performances can be provided out of the band, which can be further improved by cooperating with the front-end chips to relieve the application of the high-performance filter chips in the array. The measured results show agreement with the simulated ones, and the discrepancies at low frequencies are caused by the air gaps within the array.