H-Field Antenna Signal Isolation for Wideband EMI Rejection
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Solution Overview
Problem
Existing signal isolation and transmission devices in the electronic and electrical field suffer from small bandwidth and weak anti-interference capabilities, particularly vulnerable to common-mode electromagnetic field interference signals below 100 MHz, which affects the accuracy of measurements.
Innovation Solution
A signal isolation and transmission device utilizing high-frequency amplitude modulation and demodulation circuits in conjunction with loop antennas with conductive and insulating shielding layers, employing magnetic field coupling to transmit signals while minimizing interference, and using a magnetic shielding box to enhance isolation and reduce signal attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional isolation technologies (transformer isolation, photoelectric coupler, analog-to-digital isolation) are used, then voltage signal transmission from high voltage to low voltage is achieved, but the bandwidth is limited and anti-interference capability is weak
Solution Approach 1:
The patent transforms the signal from low-frequency voltage domain to high-frequency magnetic field domain through modulation and antenna conversion. By changing the operating frequency parameter to high-frequency carrier signals and utilizing magnetic field coupling instead of traditional electrical isolation, the system achieves both wide bandwidth and strong anti-interference capability against common-mode electromagnetic interference below 100 MHz
Solution Approach 2:
The patent replaces traditional electrical isolation mechanisms (transformers, photoelectric couplers) with magnetic field coupling through loop antennas. This substitution uses magnetic field interaction instead of electrical or optical coupling, providing superior isolation performance while maintaining signal transmission capability across a wide bandwidth range
2Object-affected harmful factors
If traditional isolation circuits are used, then voltage transmission is achieved, but common-mode electromagnetic field interference signals below 100 MHz cannot be effectively isolated
Solution Approach 1:
The patent introduces magnetic field coupling as an intermediary mechanism between the high-voltage primary side and low-voltage secondary side. The loop antennas convert voltage signals to magnetic field signals, which then couple through the isolation barrier. This intermediary magnetic field transmission provides high rejection of common-mode electromagnetic interference while preserving the integrity of the measurement signal
Solution Approach 2:
The patent converts the vulnerability to electromagnetic interference into an advantage by using magnetic field coupling. Since magnetic field coupling is inherently immune to common-mode electromagnetic interference that affects traditional electrical isolation methods, the system transforms the interference problem into a design feature that provides superior noise rejection and measurement accuracy
3Strength
If electrical isolation is used, then voltage withstand capability is achieved, but signal transmission efficiency is reduced
Solution Approach 1:
The patent replaces electrical isolation with magnetic field coupling through loop antennas. This substitution maintains the electrical isolation barrier for voltage withstand capability while using magnetic field interaction for signal transmission. The magnetic coupling provides efficient energy transfer with minimal signal attenuation compared to traditional electrical isolation methods
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 significantly improves the anti-interference capability and signal integrity by modulating signals to high-frequency carriers, reducing common-mode interference, and maintaining electrical isolation while allowing effective transmission of RF signals.
Implementation Method 1
the first H-field antenna converts the first high-frequency modulation signal into a magnetic signal
Implementation Method 2
the magnetic signal is transmitted to the second H-field antenna through magnetic field coupling
Implementation Method 3
the second H-field antenna converts the magnetic signal into a second high-frequency modulation signal
Data Source
AI summary
The invention provides a signal isolation and transmission device, comprising a high-frequency amplitude modulation circuit, a signal demodulation circuit, a first H-field antenna and a second H-field antenna. The first H-field antenna and second H-field antenna are both loop antennas with an external conductive shielding layer, and an insulating layer is wrapped outside the conductive shielding layer. The annular parts of the first H-field antenna and second H-field antenna face and abut each other. The high-frequency amplitude modulation circuit is connected with a pin of the first H-field antenna, and a pin of the second H-field antenna is connected with the signal demodulation circuit. The signal to be tested is modulated onto a high-frequency carrier signal by the high-frequency amplitude modulation circuit, and then isolated and transmitted by the two H-field antennas, which greatly improves the anti-interference effect, reduces the attenuation degree and improves the coupling degree of the signals.