Planar Asymmetric Fed Interdigital Coupling Antenna-in-Package Using FOWLP Process Operating at 60–90 GHz in Endfire Mode
Dongseop Lee, Jae-Yeong Lee, Kangseop Lee, Minkyung Kim, Myoungsun Kim, Youngno Youn, Ho-Jin Song, Wonbin Hong
Abstract
This article first reports a wideband asymmetric fed interdigital coupling antenna (AFICA) with the fan-out wafer-level package (FOWLP) process. The asymmetric fed structure is designed to realize a more compact array size. The interdigital-shaped coupling method between the elements achieves wideband impedance matching with 70- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$</tex-math> </inline-formula> feeding line. In addition, the exemplified 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 4 AFICA array package demonstrates a wide bandwidth from 60 to 90 GHz and an extremely low profile of 0.044 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda_{{0}}$</tex-math> </inline-formula> at 60 GHz. Furthermore, the prototype module is fabricated and integrated with frequency quadrupler CMOS chip. The measured results exhibit a wide bandwidth from 60 to 90 GHz and a peak gain of 9.3 dBi. The measured antenna efficiency is higher than 80%. Both fabricated package and module feature a wide scanning angle of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\pm}50^{\circ}$</tex-math> </inline-formula> and low cross-polarization levels ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\le}\!-\!18$</tex-math> </inline-formula> dB) at operating bands, respectively. The power-based de-embedding method is proposed to evaluate the performance of real-life modules and systems. The simulated and experimental results of the fan-out (FO) interconnection loss are less than 1 dB, respectively. As a result, the proposed co-planar wideband AFICA array with endfire mode design is fully compatible with various chips, such as 5G/6G communication, radar, and sensing applications.