Antenna Matching Circuit Stray Capacitance Compensation
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Solution Overview
Problem
Existing antenna apparatuses fail to effectively compensate for changes in antenna characteristics caused by surrounding conditions, such as the presence of a human body, due to limitations in impedance measurement, radiation detection, and directional detection capabilities.
Innovation Solution
An antenna apparatus incorporating a capacitance detection circuit and feedback control circuit, which detects stray capacitance and adjusts the antenna matching circuit to maintain stable characteristics by using a reactance element on both the wireless communication signal path and the sensing signal path to prevent signal leakage and infiltration, allowing for continuous compensation of antenna characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitance detection circuit is connected directly to the antenna element, then stray capacitance can be detected accurately, but the wireless communication signal may leak into the detection circuit causing interference
Solution Approach 1:
The patent divides the signal paths into separate segments: a wireless communication signal path between the antenna element and feed unit, and a sensing signal path between the antenna element and capacitance detection circuit. Reactance elements are placed on each path to selectively block unwanted signals while allowing desired signals to pass, thus preventing signal leakage and infiltration between the two functions.
Solution Approach 2:
Reactance elements serve as intermediary components that mediate between the wireless communication signal path and the sensing signal path. These reactance elements have frequency-dependent impedance characteristics that allow them to block wireless communication signals from entering the detection circuit while permitting the sensing signals to pass through to detect stray capacitance accurately.
2Reliability
If a reactance element is added to prevent signal infiltration, then signal leakage is reduced, but the device complexity increases
Solution Approach 1:
The reactance elements are designed to perform multiple functions: they serve as part of the antenna matching network for wireless communication while simultaneously acting as signal blockers for the capacitance detection circuit. This multi-functionality reduces the need for separate isolation components, thereby limiting the increase in device complexity while maintaining signal isolation reliability.
3Stability of the object's composition
If the antenna matching circuit is adjusted frequently to compensate for surrounding conditions, then antenna characteristics are maintained, but the control system complexity increases
Solution Approach 1:
The patent implements a feedback control system where the capacitance detection circuit continuously monitors stray capacitance changes caused by surrounding conditions, and the feedback control circuit adjusts the antenna matching circuit accordingly. This closed-loop feedback mechanism maintains stable antenna characteristics by automatically compensating for environmental variations without requiring complex manual intervention or overly sophisticated control algorithms.
Solution Approach 2:
The antenna apparatus performs self-adjustment through the feedback control system that automatically detects stray capacitance changes and modifies the matching circuit parameters accordingly. This self-service capability allows the antenna to maintain optimal performance under varying surrounding conditions without external intervention, reducing the complexity of external control systems while ensuring characteristic stability.
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 enables stable antenna characteristics to be maintained by accurately detecting changes in stray capacitance and adjusting the matching circuit, improving antenna efficiency and reliability across various frequency bands without deteriorating the antenna's radiation properties.
Implementation Method 1
The capacitance detection circuit is connected to the antenna element and is configured to detect stray capacitance of the antenna element
Implementation Method 2
The feedback control circuit is configured to control the antenna matching circuit in accordance with an output signal of the capacitance detection circuit
Data Source
AI summary
This disclosure provides an antenna apparatus in which stable antenna characteristics are maintained by detecting surrounding conditions that affect the antenna characteristics and appropriately compensating the antenna characteristics. More specifically, when surrounding condition such as a human body (e.g., a palm or fingers) approaches and enters an electric field of a pseudo dipole formed by an antenna element electrode, a stray capacitance is sensed and stable antenna characteristics are maintained by appropriately controlling an antenna matching circuit to compensate for a change in the antenna characteristics due to the approach of the surrounding condition.