Wideband Circularly Polarized Active Heatsink Antenna Array

A wideband active circularly polarized (CP) heatsink antenna array is designed in this article. It consists of a 3-D printing metal structure and a low-temperature co-fired ceramic (LTCC) substrate. The metal structure is a $4\times 4$ waveguide array, serving dual purposes as both a heatsink and an electromagnetic radiator. The substrate is placed under the metallic array, with a feeding network layer inside and a chip circuit layer on the surface. To generate a CP radiation wave, the antipodal linearly tapered slot antenna (ALTSA) is used as the heatsink element, which is fed by the stripline in the substrate. Two ridges and a back cavity are designed in each element to realize the wideband energy conversion from the guided wave in the stripline to the rectangular waveguide. A prototype of the heatsink antenna array without a chip is fabricated, and the electromagnetic performance is tested. The measured results demonstrated that the proposed antenna array obtains an impedance bandwidth ( $\vert {S}_{11}\vert \lt -10$ dB) of 50% and an axial ratio (AR) bandwidth (AR < 3 dB) of 33.6%, respectively. The peak gain is 19 dBi at 34.7 GHz. Furthermore, an active antenna array, with a power amplifier (PA) integrated on the bottom of the substrate is also measured, which can achieve an effective peak gain of 39.7 dBi. The measured thermal performance reveals that a significant temperature drop of $80~^{\circ }$ C is achieved by loading the metal heatsink on the LTCC package, ensuring the normal operation of the PA.