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In this paper, a new low-cost silicon interposer technology is introduced. Organic lamination processes are used for multi-layer signals and through via-holes are made by adjusting UV laser drilling. It is possible to make a 80 μm minimum through via using laser drilling. The fabricated interposer has an only 230 μm thickness and it has more than 6 metal layers including thin film metal. In this interposer, thin film spiral inductors and MIM capacitors can be integrated in the silicon substrate. For low-loss and high isolation, a TOLV (Through Organic Lining Via) and COLV (Coaxial Lining Via) can be made. The fabricated coaxial via has very low loss, 0.07 dB at 10 GHz, and high isolation properties for a wide frequency range, more than 40 dB at 0~40 GHz.

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A compact multiple‐input multiple‐output (MIMO) antenna design for application to smart glasses is proposed in this letter. The proposed MIMO antenna system is comprised of two symmetrical meander antennas operating in the 2.4‐GHz wireless local area network band and a T‐shaped ground for high isolation. The operation mechanism of the proposed MIMO antennas can be explained using the analysis of a three‐port network. Accordingly, the T‐shaped ground plane operates as a decoupling structure such that the isolation between antennas can be controlled by tuning the T‐shaped ground plane. The reflection coefficient characteristic was measured to be less than −7.5 dB, whereas the isolation obtained was higher than 15 dB. The diversity performance was evaluated using the measured three‐dimensional radiation patterns, and the envelope correlation coefficients in the target band were less than 0.1.

This paper introduces a miniaturized Butler matrix design method using a folded structure. The Butler matrix was fabricated in multilayers using low-temperature co-fired ceramics (LTCC) and designed to operate at 28 GHz. The conventional one-plane Butler matrix has a major disadvantage in that the length and volume of the system inevitably have to be increased. By using the proposed folded structure, the length can be reduced more than two times compared to the general one-layer Butler matrix. In order to minimize the loss of the Butler matrix, it was designed in a stripline structure by forming a ground plane on the upper and lower surfaces of each layer. A signal is transmitted between the layers through via holes. A 4 × 4 Butler matrix was fabricated and measured for the demonstration of the proposed concept. The proposed Butler matrix was measured through a precisely calibrated antenna chamber with closed cell absorbers. The dimensions of the fabricated Butler matrix are 14 mm × 20 mm × 1.52 mm. The beam of the fabricated Butler matrix can be properly steered in a total of four directions.