Dynamic Antenna Matching Circuit for VHF UHF Impedance
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Solution Overview
Problem
Existing antennas, such as VHF/UHF man-portable and vehicular antennas for military communications, exhibit poor impedance matching with transmitters, leading to high voltage standing wave ratios (VSWRs) and requiring lossy matching networks that result in high loss and low gain, necessitating a high-speed, automatic antenna matching solution.
Innovation Solution
A dynamic antenna matching system featuring an electronically tunable antenna matching circuit, directional couplers, gain and phase detectors, and a controller that determines and adjusts circuit parameters to improve impedance matching, including capacitors, inductors, and electronic switches for real-time tuning and phase error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If banded antennas are used to reduce VSWR, then impedance matching is improved, but loss increases and gain decreases due to lossy matching networks
Solution Approach 1:
The patent applies dynamics by implementing an electronically tunable matching network that can dynamically adjust its impedance characteristics in real-time. The system uses voltage-controlled oscillators and variable capacitors to adapt the matching network's parameters, allowing it to maintain optimal impedance matching across different frequencies without incurring the losses associated with fixed, lossy matching networks. This dynamic adjustment capability resolves the contradiction by enabling good matching performance while minimizing energy loss through active compensation rather than passive lossy elements.
Solution Approach 2:
The patent employs parameter changes by varying the electrical characteristics (capacitance, inductance, resistance) of the matching network components based on the operating frequency and antenna conditions. The system measures the actual antenna impedance and adjusts the matching network parameters accordingly, transforming the fixed-parameter matching networks into variable-parameter systems. This allows the network to achieve optimal matching at different frequencies without relying on lossy fixed components, thereby reducing energy loss while maintaining reliable impedance matching.
2Reliability
If banded antennas with matching networks are used, then VSWR is reduced, but device complexity increases due to additional matching network components
Solution Approach 1:
The patent applies universality by designing a matching network that serves multiple functions simultaneously: impedance matching, frequency selection, and adaptive tuning. The electronically tunable components and control system enable the same network to handle different frequency ranges and antenna configurations without requiring separate matching networks for each band. This multi-functionality reduces device complexity compared to having multiple fixed matching networks, while maintaining reliable impedance matching across various operating conditions.
3Reliability
If fixed matching networks are used in antenna base, then impedance match is improved, but adaptability decreases when frequency ranges need to be changed
Solution Approach 1:
The patent applies dynamics by implementing an electronically tunable matching network that can dynamically adjust its impedance characteristics in real-time. The system uses voltage-controlled oscillators and variable capacitors to adapt the matching network's parameters, allowing it to maintain optimal impedance matching across different frequencies without incurring the losses associated with fixed, lossy matching networks. This dynamic adjustment capability resolves the contradiction by enabling good matching performance while minimizing energy loss through active compensation rather than passive lossy elements.
Solution Approach 2:
The patent employs preliminary action by pre-calculating and storing optimal matching parameters for different frequency ranges and antenna configurations. The control system retrieves these pre-computed parameters and applies them to the tunable matching network, enabling rapid adaptation to different operating conditions without requiring complex real-time calculations. This preliminary preparation allows the system to maintain reliable impedance matching while achieving high adaptability across frequency ranges.
Data Source
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Figure 2A
AI summary
An antenna matching system includes an electronically tunable antenna matching circuit, a first directional coupler (120), a first gain and phase detector (122), a second directional coupler (124), a second gain and phase detector (126), and a controller (128). The first directional coupler is configured to receive forward and reflected signals. The first gain and phase detector is configured to output a first magnitude measurement and a first phase measurement based on the signals received at the first directional coupler. The second directional coupler is also configured to receive the forward and reflected signals. The second gain and phase detector is configured to output a second magnitude measurement based on the signals received at the second directional coupler. The controller is configured to: determine circuit parameters based on the first magnitude and phase measurements; tune the matching circuit based on the circuit parameters; and check for phase error based on the second magnitude measurement.