Multi-Band Antenna Impedance Matching for Fast RF Tuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radiofrequency transmission and reception systems face impedance mismatch issues due to varying antenna impedances, leading to significant losses, especially in applications with high miniaturization constraints, and existing solutions are either slow, power-consuming, or not adaptable to different frequency bands.
Innovation Solution
An automatic impedance matching method using a calculation processor and a matching network with adjustable impedances, measuring current and voltage to calculate and adjust the impedance values to match the antenna impedance to a nominal load or input impedance, allowing operation across multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bidirectional coupler is used to detect mismatch and control the impedance matching network, then impedance matching can be achieved, but the circuit becomes slow, power-consuming, and not integrable in an integrated circuit chip
Solution Approach 1:
The patent extracts the essential measurement function from the complex bidirectional coupler system and implements it using a simple series impedance element combined with voltage ratio measurement. This extraction eliminates the need for bulky coupler components while retaining the core impedance detection capability, enabling integration in standard CMOS technology.
Solution Approach 2:
The patent replaces the hardware-based bidirectional coupler detection mechanism with a computational approach using a processor that calculates impedance from voltage ratio measurements. This substitution of mechanical/electrical hardware with algorithmic processing reduces circuit complexity and power consumption while improving integration feasibility.
2Reliability
If an impedance matching network is used to compensate for antenna impedance variations, then transmission chain performance can be maintained, but the matching process is iterative and slow
Solution Approach 1:
The patent implements preliminary action by pre-calculating the optimal impedance matching parameters across the entire frequency range and storing them in lookup tables. When operation begins, the system can immediately select the appropriate pre-computed parameters based on the operating frequency, eliminating the need for slow iterative adjustments during actual operation.
Solution Approach 2:
The patent makes the impedance matching network dynamically adjustable across a wide frequency range (2.4 GHz to 5.8 GHz) using voltage-controlled capacitors and inductors. This dynamic capability allows the system to quickly adapt to different frequency bands without iterative tuning, as the matching parameters can be electronically reconfigured instantaneously.
3Reliability
If a matching network is designed for a well-defined radio frequency, then it can achieve good matching at that frequency, but it does not allow correct operation if the operating frequency is modified
Solution Approach 1:
The patent implements universality by designing an impedance matching network that can operate correctly across multiple frequency bands (2.4 GHz, 5.8 GHz, and intermediate frequencies). The network uses voltage-controlled reactive elements and pre-computed matching parameters for different frequencies, allowing a single network design to serve multiple frequency bands without requiring separate matching networks for each band.
Solution Approach 2:
The patent changes the electrical parameters of the matching network components dynamically based on the operating frequency. By using voltage-controlled capacitors and inductors whose values can be adjusted electronically, the system maintains optimal matching performance across different frequency bands. The processor selects appropriate parameter sets from pre-computed data, enabling the same physical network to adapt its electrical characteristics to different operating conditions.
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 solution effectively reduces impedance mismatch losses, enabling efficient radiofrequency transmission and reception across various frequency bands with improved precision and adaptability, maintaining high efficiency and accuracy.
Implementation Method 1
a measurement impedance, Za, of variable value, inserted in series between the output of the amplifier PA and the impedance matching network MN... The impedance Za makes it possible to measure the current i which leaves the amplifier PA
Implementation Method 2
calculation of new values e of adjustable impedances of the matching network which make it possible to obtaining an overall amplifier load impedance as close as possible to the nominal load impedance... control of the matching network MN to adjust the adjustable impedances to these new values
Data Source
Figure 1
Figure 2~5
AI summary
The invention relates to an automatic impedance matching method for an antenna for a radiofrequency transmission circuit. An impedance matching network (MN) is inserted between the amplifier (PA) and the antenna (ANT). The output current i and voltage V of the amplifier and the phase-shifting thereof are measured by variable measurement impedance (Ca), and the complex impedance of the amplifier load is deduced therefrom. The impedance of the antenna is calculated on the basis of said complex impedance and on the basis of the current known values of the impedances of the matching network. New values for the matching network are calculated from the found value of the impedance of the antenna, making it possible to match the load to the nominal impedance of the amplifier. The measurement impedance has a value that is controllable by the calculation processor in accordance with the use, and in particular in accordance with the working frequency and with the nominal impedance of the amplifier. The invention can be used in miniature antennas for telephony or in medical telemetry.