Wireless Microphone PCB Antenna Layout With Shielded Feed Path
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Solution Overview
Problem
Conventional wireless microphone devices using a circuit board as a dipole antenna element face issues with shortened effective length, leading to suboptimal radiation characteristics, and increased device size due to the placement of oscillation circuits and feeding paths.
Innovation Solution
The wireless microphone device configures a circuit board into sectioned areas functioning as dipole antenna elements, with a high-frequency shield covering the feeding path to prevent electromagnetic coupling and maintain desired radiation characteristics, and includes a metal case to form a high-frequency shield around the oscillation circuit, amplifier circuit, and band-limiting filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the circuit board is used as the antenna element of the dipole antenna and the oscillation circuit is provided on the circuit board, then the device size can be reduced, but the length of the circuit board that effectively acts as the antenna element is shortened, resulting in degraded radiation characteristics
Solution Approach 1:
The circuit board is divided into a first circuit area and a second circuit area, with the first circuit area serving as the antenna element and the second circuit area housing the oscillation circuit. This segmentation allows the antenna function and circuit function to be separated on the same board, maintaining effective antenna length while integrating the oscillation circuit to reduce overall device size.
Solution Approach 2:
A feeding path is provided to connect the oscillation circuit in the second circuit area to the antenna element in the first circuit area. This feeding path acts as an intermediary, enabling the oscillation circuit to be positioned separately from the antenna element while still providing the necessary high frequency signal, thus preserving antenna effectiveness while allowing circuit integration.
2Device complexity
If the feeding path is provided on the circuit board without shielding, then electromagnetic coupling occurs between the oscillation circuit and the antenna element, causing degradation of radiation characteristics
Solution Approach 1:
A shield is provided between the oscillation circuit and the antenna element along the feeding path. This shield acts as an intermediary that blocks electromagnetic coupling between the two components, preventing degradation of radiation characteristics while allowing both the oscillation circuit and antenna element to be integrated on the same circuit board.
3Reliability
If traditional separate antenna elements are used instead of the circuit board, then desired radiation characteristics can be obtained, but the device size and manufacturing cost increase
Solution Approach 1:
The circuit board is designed to serve dual functions: as the substrate for mounting the oscillation circuit and as the antenna element itself. By merging the circuit board function with the antenna function, the need for separate antenna components is eliminated, reducing device size and manufacturing cost while maintaining radiation characteristics through proper area segmentation and shielding.
Solution Approach 2:
The circuit board is designed to perform multiple functions simultaneously: it serves as the mounting substrate for the oscillation circuit, provides the feeding path for the high frequency signal, and acts as the antenna element for radiation. This multi-functionality eliminates the need for separate antenna components, reducing device size and complexity.
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
This configuration allows for miniaturization of the circuit board with an oscillation circuit while maintaining desired radiation characteristics without increasing the device size, and provides a high-frequency shield to prevent electromagnetic interference, enhancing the device's performance and manufacturing efficiency.
Implementation Method 1
an oscillation circuit which is arranged in the first circuit area and generates a high frequency signal on a basis of a voice signal from a sound collecting element
Implementation Method 2
a high frequency shield covering at least a part of the feeding path
Data Source
AI summary
To provide a wireless microphone device that enables a circuit board, which is to be provided with an oscillation circuit, to be decreased in size without deteriorating radiation characteristics.The wireless microphone device is configured to include: a circuit board 5 that is sectioned into circuit areas 11a and 11b and makes the respective circuit areas function as antenna elements of a dipole antenna; an oscillation circuit 21 that is arranged in the circuit area 11b and generates a high frequency signal on the basis of a voice signal from a microphone 2a; a feeding path for feeding the high frequency signal to an electrically conductive layer 11 in the circuit area 11b through a feeding point positioned on the circuit area 11a side distant from the oscillation circuit 21; and a high frequency shield covering at least a part of the feeding path. The high frequency shield is formed by covering the feeding path with a metal case 12 having an opening at a bottom face and conducting the metal case 12 to the electrically conducting layer 11 in the circuit area 11b.