PCB-Coax Antenna Connection Assembly for Low Return Loss
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Solution Overview
Problem
Existing coaxial cable connections to printed circuit boards in antenna systems suffer from significant energy loss and parasitic inductance, leading to poor impedance matching and increased return loss, particularly at high frequencies, due to exposed inner conductors and bent portions.
Innovation Solution
A connection assembly with a ground structure that includes a metal pattern area on the printed circuit board, arranged on both sides of the exposed inner and outer conductors, and a ground connector to form a conducting loop, ensuring a stable TEM mode transmission and reducing radiation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner conductor is exposed and bent to pass through the via hole, then electrical connection is achieved, but parasitic inductance increases and impedance matching deteriorates
Solution Approach 1:
The patent introduces a ground structure as an intermediary element between the inner conductor and the via hole. This ground structure provides a reference potential and reduces the parasitic inductance by creating a more direct electromagnetic path, thereby improving impedance matching while maintaining electrical connection.
Solution Approach 2:
The patent changes the geometric parameters of the connection structure by introducing a ground structure with specific dimensions and positioning. This modifies the electromagnetic field distribution and reduces the parasitic inductance, improving the impedance matching between coaxial cable and microstrip line.
2Ease of manufacture
If the inner conductor is exposed to ambient, then assembly is simplified, but energy loss due to radiation increases
Solution Approach 1:
The ground structure serves as a mediator that shields the exposed inner conductor from the ambient environment. It provides electromagnetic containment, reducing radiation loss while maintaining the simplicity of the assembly process.
Solution Approach 2:
The patent converts the potentially harmful radiation from the exposed inner conductor into a controlled electromagnetic field by introducing the ground structure. This transforms the radiation loss into a beneficial confined field that improves signal integrity while maintaining assembly simplicity.
3Volume of moving object
If the coaxial cable extends parallel to the printed circuit board, then space is saved, but radio frequency performance deteriorates due to increased return loss
Solution Approach 1:
The patent changes the geometric parameters of the transition structure by introducing a ground structure with optimized dimensions and positioning. This modifies the electromagnetic field distribution along the parallel extension, reducing return loss and improving radio frequency performance while maintaining compact space utilization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves radio frequency performance by minimizing energy loss and enhancing impedance matching, resulting in smoother signal transition from coaxial cables to microstrip lines, reducing return loss and spatial radiation.
Implementation Method 1
ensuring a stable TEM mode transmission and reducing radiation loss
Implementation Method 2
reducing radiation loss
Data Source
AI summary
A connection assembly for an antenna includes a printed circuit board and a coaxial cable connected to the printed circuit board. A transmission trace and a solder pad are provided on the printed circuit board. An opening for receiving an end portion of the coaxial cable is also provided in the printed circuit board, and an exposed outer conductor of the end portion extends into the opening, and an exposed inner conductor reaches the solder pad. The connection assembly further includes a ground structure, which is electrically connected to a ground metal layer on a second surface of the printed circuit board, and the ground structure is at least partially arranged on both sides of the exposed inner conductor and/or the exposed outer conductor.