ANTENNAS ARE EVOLVING from conventional discrete structures to antenna-in-package (AiP) solutions. In a novel approach, a circularly polarized antenna was recently integrated with active circuits at 60 GHz in the package by Mei Sun, Muhammad Faeyz Karim, and Ong Ling Chuen from Singapore's Institute for Infocomm Research together with Ya-Qiong Zhang, Yong-Xin Guo, and Mook Seng Leong from the National University of Singapore. This active receiving antenna array was designed and fabricated using low-temperature co-fired-ceramic (LTCC) technology.
At 60 GHz, it is difficult to design an integrated, circularly polarized antenna with both high gain and wide axial-ratio and impedance bandwidths. In the LTCC design, high gain is achieved with a patch array of 4 x 4 elements. For their part, the wide axial-ratio and impedance bandwidths rely on a stripline sequential rotation feeding scheme. Through the application of that scheme, the circularly polarized array exhibits a wide impedance bandwidth (SWR
The design's aperture-coupled topology and stripline feeding features combine to make the antenna less sensitive to its dielectric and metal layers. In addition, the antenna design is decoupled from the package's physical properties, which simplifies simulation and modeling. A 21-dB low-noise amplifier (LNA) is integrated into the package by applying a bond-wire compensation scheme and low-loss transition optimization. The fabricated prototype, which measures 13 x 20 x 1.4 mm, is estimated to have peak overall gain of at least 35 dBi. See "Integration of Circular Polarized Array and LNA in LTCC as a 60-GHz Active Receiving Antenna," IEEE Transactions On Antennas And Propagation, Aug. 2011, p. 3083.