Angular Branch-Line Coupler for Compact Mobile PCBs
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Solution Overview
Problem
Conventional branch-line couplers occupy a large area on printed circuit boards, making them unsuitable for compact applications such as mobile communications.
Innovation Solution
The design incorporates angular transmission lines to minimize the size of the branch-line coupler while maintaining high performance, using a configuration of L-shaped and T-shaped branch transmission lines and connection parts to reduce the overall dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional quarter-wavelength lines are used to construct a branch-line coupler, then the coupler achieves standard 3 dB coupling performance, but the occupied area on the PCB becomes large
Solution Approach 1:
The patent replaces conventional straight quarter-wavelength transmission lines with angular transmission lines that incorporate bent or curved geometries. This curvature allows the transmission lines to achieve the required electrical length while occupying less physical space on the PCB, thereby reducing the overall area of the branch-line coupler while maintaining its coupling performance
Solution Approach 2:
The patent utilizes multi-layer PCB structures to route transmission lines in three-dimensional space rather than confined to a single plane. By transitioning signals between different layers and using vertical spacing, the design achieves the necessary electrical path lengths for proper coupling operation without proportionally increasing the planar footprint on the PCB
Data Source
AI summary
A small-scale branch-line coupler suitable for use in mobile devices includes a first, second, third, and fourth ports, respectively acting as input, transmission, coupled, and isolated ports. A first, second, third, and fourth connection parts are connected to the ports and transmission lines. First angular transmission lines are between first and second ports, third angular transmission lines are between third and fourth ports. A third long strip transmission line connects the first port and the fourth port. A fourth long strip transmission line connects the second port and the third port. The branch-line coupler occupies a small area and has high performance.