Multi-Beam 5G Antenna With Miniaturized Butler Matrix Using Stacked LTCC

In this work, we present a compact four-direction beamforming 5G antenna based on a stacked
$4\times4$
Butler matrix and a microstrip patch array antenna. The proposed beamforming antenna is a stacked-up structure using the low temperature co-fired ceramics (LTCC) process and thus its size can be significantly reduced by compared to a conventional beamforming antenna with a single-layer
$4\times4$
Butler matrix. Moreover, spurious radiation generated from the Butler matrix can be effectively suppressed due to shielding effects inherent to the multilayer substrate. The fabricated beamforming antenna is composed the stacked
$4\times4$
Butler matrix with striplines and the
$4\times1$
array microstrip patch antenna. The overall size of the fabricated antenna system is 22.02 mm
$\times5.93$
mm
$\times1.20$
mm. The beam steering angles are measured to be −16°, 45°, −45° and 16°.