Active Matching Network for Miniature Antenna Bandwidth
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Solution Overview
Problem
Existing miniature resonant antennas face limitations in bandwidth and transmission efficiency due to their small form factor, with passive designs nearing performance limits and requiring improvements in active matching techniques to enhance gain and bandwidth.
Innovation Solution
An active matching network using a cross-coupled transistor pair with a matching circuit configured to provide a complex negative impedance, comprising resistance, inductance, and capacitance, is employed to match the impedance of a high Q miniature antenna, effectively canceling the imaginary component of the antenna impedance while maintaining the real component close to the signal source impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If passive antenna design is used to minimize antenna size, then the antenna form factor is reduced, but the bandwidth and transmission efficiency are limited and approach fundamental performance limits
Solution Approach 1:
The patent changes the impedance parameters of the antenna by introducing an active matching network that provides negative resistance and reactance. This transforms the antenna's input impedance characteristics, enabling bandwidth expansion while maintaining the physically small antenna dimensions. The active circuit dynamically adjusts impedance parameters to overcome the fundamental limits of passive electrically small antennas.
Solution Approach 2:
The patent introduces an active matching network as an intermediary component between the signal source and the small antenna. This intermediary circuit performs impedance transformation and provides negative resistance to cancel losses, thereby improving transmission efficiency and bandwidth without requiring changes to the antenna's physical structure.
2Volume of moving object
If passive antenna design is used to minimize antenna size, then the antenna form factor is reduced, but the transmission efficiency deteriorates
Solution Approach 1:
The active matching network changes the resistive component of the antenna's input impedance by providing negative resistance that cancels the positive resistance losses. This parameter transformation effectively reduces the total loss resistance, improving transmission efficiency while the antenna maintains its small physical size.
3Productivity
If conventional active matching networks are used to improve bandwidth, then bandwidth is enhanced, but transmission efficiency improvement is limited and further enhancement is needed
Solution Approach 1:
The patent employs a novel active matching network topology that provides both negative resistance and negative reactance simultaneously. This dual-negative-impedance approach changes both the resistive and reactive parameters of the antenna system, achieving superior transmission efficiency improvement (38 dB) compared to conventional active matching networks while maintaining expanded bandwidth.
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 approach more than triples the 3 dB bandwidth and provides a 10 dB improvement in transmission efficiency compared to passive designs, while maintaining the compact size of the antenna, and offers a 38 dB improvement over previous active matching networks, enhancing the overall performance of miniature resonant antennas.
Implementation Method 1
The matching network is configured to match an impendence near resonance of the high Q miniature antenna to an input impedance using a complex negative impedance comprising resistance, inductance and capacitance
Data Source
AI summary
An active matching network for impedance matching to a miniature antenna, comprising a cross-coupled transistor pair, where each transistor has an emitter, base and collector, the emitter of a first transistor forms an input terminal, the emitter of a second transistor forms on output terminal, the collector of the first transistor coupled to the base of the second transistor, the collector of the second transistor coupled to the base of the first transistor, and a matching circuit coupled between the collectors of the first and second transistors. The matching network is configured to match an impendence near resonance of the high Q miniature antenna to an input impedance using a complex negative impedance comprising resistance, inductance and capacitance.