Design of Antenna on Glass Integrated Passive Device for WLAN Applications

An antenna miniaturization technique that can substantially miniaturize an antenna to allow its incorporation into a compact package for WLAN (2.4-2.484 GHz) applications is proposed. For this purpose, the semiconductor-based glass integrated passive device (GIPD) manufacturing technology is adopted. However, the inherently lower dielectric constant and more limited number of layers that can be used in a GIPD than low temperature co-fired ceramic (LTCC) pose a serious challenge in miniaturization. To facilitate the design, an equivalent circuit approach is applied to the loop-based antenna in which the structure is conveniently integrated with the ground trace in the semiconductor fabrication process to improve both miniaturization and radiation efficiency. The loop antenna incorporates a strip that is capacitively fed by the coplanar waveguide (CPW) feedline, and the combined equivalent circuit shows that without detuning the structure of the antenna, resonance can be obtained simply by adjusting the equivalent capacitance between the feedline and structure. Furthermore, the ground of the CPW is part of the antenna, so its length affects the resonant frequency of the antenna. Under these conditions, the resonant length of the loop antenna is not necessarily one wavelength, so the antenna can be made electrically small. Therefore, the antenna proposed herein has dimensions 2.4 × 1.1 (0.019 λ
₀
× 0.009 λ
₀
) mm
²
, occupying only 2.4% of the package area (9.7 × 9.7 mm
²
), allowing the flexibility of the integration of other components in the package. The package is mounted on the printed circuit board (PCB) with a ground plane of size 100 × 50 mm
²
. The effect of the size of the ground plane is discussed. The radiation efficiency is 58% in the WLAN band (2.4-2.484 GHz). Therefore, the proposed method is very useful for designing a package antenna.