Antenna Module Ground Layout to Suppress Unintended Resonance
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Solution Overview
Problem
When a conductive path from the motherboard to the ground electrode used as an antenna is relatively long, stray capacitance causes the ground electrode to become electrically floating, leading to unintended resonance with other antenna devices, resulting in increased loss in antenna characteristics.
Innovation Solution
The antenna module includes a first substrate with a radiation electrode and a ground electrode, a second substrate with another radiation electrode and ground electrode, a third substrate with a ground electrode, and a flat plate-shaped connection member between the first and second substrates, with a ground electrode on the connection member. This configuration reduces the potential difference between the ground electrodes, preventing unnecessary resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ground electrode is disposed away from the motherboard to suppress reflection of radio waves, then the antenna characteristics are improved, but the conductive path becomes long causing stray capacitance and potential difference, leading to unintended resonance and increased loss
Solution Approach 1:
A connection member with a ground electrode is introduced as an intermediary between the motherboard and the antenna device. This connection member acts as a mediator to equalize potential between the motherboard ground electrode and the antenna device ground electrode, preventing unintended resonance while allowing the antenna to be disposed away from the motherboard for reduced radio wave reflection.
2Reliability
If the ground electrode is disposed away from the motherboard, then reflection of radio waves is suppressed, but the ground electrode becomes electrically floating due to stray capacitance, causing unintended resonance
Solution Approach 1:
The connection member with its ground electrode serves as an intermediary that maintains electrical potential stability. It provides a stable reference potential to the antenna device ground electrode through capacitive coupling with the motherboard, preventing the ground electrode from becoming electrically floating while allowing physical separation for reduced radio wave reflection.
Solution Approach 2:
The connection member is designed to equalize the potential between the motherboard ground electrode and the antenna device ground electrode. By positioning the connection member's ground electrode between these two grounds and allowing capacitive coupling, the system achieves equipotential conditions, preventing unintended resonance caused by potential differences.
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 configuration effectively suppresses unnecessary resonance and prevents an increase in loss in antenna characteristics, even when the antenna device is disposed away from the motherboard.
Implementation Method 1
when a conductive path from the motherboard to the ground electrode used as an antenna is relatively long, due to the stray capacitance, the potential of the ground electrode used as an antenna becomes higher than the potential of the ground electrode included in the motherboard
Data Source
AI summary
A communications apparatus an antenna module include a first substrate on which a first radiation electrode and a first ground electrode are disposed; a second substrate on which a second radiation electrode and a second ground electrode are disposed; a third substrate on which a third ground electrode is disposed; and a first connection member having a flat plate shape and connected between the first substrate and the second substrate, a fourth ground electrode being disposed on the first connection member. A radio frequency signal is transmitted to the first radiation electrode through the first connection member, and a main surface of the first connection member is in contact with a main surface of the third substrate.