Butler matrix antenna and manufacturing method thereof

Multi-beam Butler matrix antenna with reduced footprint using a folded-stack feed line structure

This technology is a stacked beam-switching antenna and its manufacturing method, where the planar Butler matrix feed line is divided and folded into two layers with a ground plane in between, then reconnected via via-holes. The input ports and radiation assembly are aligned to face the same direction.

While Butler matrices are widely used in smart antennas for their ability to easily create fixed multi-beams with relatively few components, they have historically been difficult to integrate into small spaces or compact devices due to the large footprint of the feed network.

This technology reduces the substrate footprint by approximately 40% while maintaining radiation patterns and gain comparable to conventional planar designs by stacking the feed line in two layers and connecting the cut sections with multiple via-holes. A radiation assembly is formed by stacking a second ground plane with apertures and a radiator layer on top. It can be applied to 5G small cells, IoT terminals, and automotive beamforming modules, significantly saving antenna space while preserving multi-beam performance.

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Key Features:

• A structure where the completed Butler matrix feed line is cut into a folded shape, dividing it into input-side and radiator-side sub-feed lines
• A configuration stacking the first sub-feed line under the first substrate, the first ground plane on top of the first substrate, and the second sub-feed line on top of the second substrate
• Multiple via-holes that electrically connect the cut sections of the two sub-feed lines to form a single Butler matrix feed line
• A radiation assembly formed by sequentially stacking a third substrate, a second ground plane with apertures, a fourth substrate, and multiple radiators on the second sub-feed line, oriented in the same direction as the input ports

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