A 3D Vertically-Integrated Wideband Filter Antenna for X-Band Applications
Tao Fang,
Tao Tang,
Xiangyan Zhao and
Wei Hu
This paper presents a compact wideband integrated filtering antenna for X-band applications enabled by a three-dimensional (3D) vertical-interconnect architecture. A self-packaged electromagnetic platform is constructed on a multilayer substrate with a central air cavity, realizing high-density monolithic integration of a slotted patch radiator and a seventh-order microstrip bandpass filter (BPF). Distinct from conventional planar cascaded filtering antennas, the proposed 3D collaborative electromagnetic structure - formed by the air cavity, a perimeter vertical interconnect access (VIA) array, and multilayer ground planes - provides low-loss signal transmission and effectively suppresses parasitic coupling within a compact volume. To enhance radiation performance, the patch is co-optimized via slot loading, chamfering, and asymmetric feeding to extend the surface-current path, lower the resonant frequency, and broaden the impedance bandwidth, achieving a 45.27% reduction in patch area relative to the initial design. To accommodate the BPF within the packaging boundary, spatial adaptation and impedance matching are achieved through a tilted layout, arc-shaped port extension, and vertical feed VIAs while maintaining essentially unchanged electrical performance. Measured results demonstrate a 40.3% fractional bandwidth from 7.99 to 12.02 GHz, a peak gain of 6.85 dBi, good out-of-band/harmonic suppression, and stable radiation patterns. The overall size is 1.17λ0 × 1.17λ0 × 0.12λ0. The proposed 3D vertical-interconnect and multifunctional self-packaged co-design methodology offers an effective solution for broadband, miniaturized, high-isolation filtering antennas and system-on-package (SoP) RF front ends.
