Direction Estimation Using Parasitic Antenna Impedance Control
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Solution Overview
Problem
Existing methods for estimating the direction and position of a person using radio signals require multiple antennas capable of observing delay time and phase information, leading to increased costs and complexity, and often necessitate phase synchronization between transmitter and receiver, which is challenging, especially over long distances.
Innovation Solution
A position sensor system using at least one reception antenna and one parasitic antenna with a variable load, where a controller sets the impedance value, allowing the system to estimate the direction of arrival without obtaining phase information from the transmitter side by calculating complex propagation channels based on signal strength variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple antennas capable of observing delay time and phase information are used, then direction estimation accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts only the necessary information (signal strength) from the received signal, discarding the need for complex phase and delay time observations. By using a single receiver with a parasitic antenna system, the patent extracts directional information through signal strength variations caused by impedance changes, rather than requiring multiple receivers to observe phase differences.
Solution Approach 2:
The invention changes the observation parameter from phase information to signal strength information. By varying the impedance of the parasitic antenna and measuring the corresponding signal strength changes at the receiver, the system can estimate direction without requiring phase synchronization or multiple antennas. This parameter transformation resolves the contradiction by maintaining measurement capability while reducing system complexity.
2Measurement precision
If phase information regarding the transmitter side is obtained, then position and direction estimation is improved, but ease of operation deteriorates due to phase synchronization requirements
Solution Approach 1:
The system performs self-service by using the parasitic antenna to locally generate reference signals through impedance variation. The receiver measures signal strength changes that inherently contain directional information, eliminating the need for external phase synchronization with the transmitter. The system serves itself by creating the necessary measurement conditions through impedance control rather than requiring coordinated phase information from the transmitter side.
3Measurement precision
If a plurality of antennas are used to observe delay time and phase information, then direction estimation capability is improved, but manufacturing cost increases
Solution Approach 1:
The parasitic antenna serves multiple functions: it acts as both a passive radiating element and a controllable impedance variable that modulates the received signal. By changing the impedance of this single parasitic antenna, the system can steer the beam and measure signal strength from different directions, replacing the need for multiple active antenna elements. This multi-functionality reduces manufacturing cost while maintaining direction estimation capability.
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 simplifies the hardware configuration, reduces costs by eliminating the need for precise phase synchronization, and effectively estimates the direction of a moving body using radio signals with a smaller number of receivers, while maintaining accurate direction estimation.
Implementation Method 1
a transmitter that transmits a transmission signal to a predetermined area in search of an organic body; a receiver that receives a first signal, the first signal being formed of a combination of a signal received by the reception antenna and a signal received by the parasitic antenna, the signal received by the reception antenna and the signal received by the parasitic antenna being derived from the transmission signal
Data Source
AI summary
A sensor includes a reception antenna, a parasitic antenna terminating in a variable load, a controller, a transmitter transmitting a transmission signal, a receiver, a memory, and a processor. The controller sets an impedance value of the variable load. The receiver receives a first signal formed of signals received by the antennas and derived from the transmission signal, and the signal received by the parasitic antenna corresponding to the impedance value. The memory stores a first signal strength value of the first signal corresponding to the impedance value. The processor sets candidates of a complex propagation channel, calculates second signal strength values of a second signal respectively corresponding to the candidates, estimates a target complex propagation channel by selecting a candidate corresponding to a minimum difference among differences between the first signal strength value and the second signal strength values, and estimates a direction of arrival of the first signal.