Electrically Small Antennas Using Coupled Resonant Loops for Directional Resolution
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Solution Overview
Problem
Electrically small antennas face limitations in radiation efficiency and bandwidth due to their small size, making it challenging to achieve super-directivity and precise directionality of electromagnetic waves, especially with mutual coupling and fabrication tolerances complicating the realization of necessary excitation coefficients.
Innovation Solution
A receiver system comprising a plurality of antennas and a signal processing circuit with coupled resonant loops that amplify the phase difference between input signals, effectively increasing the sensitivity pattern and allowing for directional detection of electromagnetic waves, even with small antenna arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electrical dimensions of an antenna are decreased to make the antenna electrically small, then the antenna size is reduced, but the radiation efficiency and bandwidth decrease
Solution Approach 1:
The patent divides a single electrically small antenna into multiple smaller antenna elements arranged in an array configuration. By segmenting the antenna system into N elements, the overall radiation efficiency is improved while maintaining the electrically small footprint, as each element contributes to the total radiated power
Solution Approach 2:
The patent combines multiple antenna elements into a unified array system with shared signal processing circuitry and coordinated excitation. By merging the functionality of individual elements and applying super-directive beamforming, the system achieves enhanced radiation efficiency and bandwidth that exceeds what a single small antenna could provide
2Volume of moving object
If the electrical dimensions of an antenna array are decreased to make the array electrically small, then the array size is reduced, but the ability to achieve super-directivity and resolve direction of arrival deteriorates
Solution Approach 1:
The patent changes the excitation parameters of the antenna elements by applying non-uniform, widely varying complex excitation coefficients with different amplitudes and phases. This parameter optimization enables super-directive beam patterns that sharply resolve direction of arrival even when the overall array electrical dimensions are smaller than traditional limits suggest
Solution Approach 2:
The patent implements dynamically adjustable excitation coefficients that can be adapted based on the incident wave characteristics. The system dynamically optimizes the beamforming weights to maintain super-directivity performance across different operating conditions and arrival angles, enabling precise direction resolution from electrically small arrays
3Use of energy by moving object
If widely varying excitation coefficients are applied to achieve super-directional characteristics, then directionality is improved, but mutual coupling between elements and fabrication tolerances complicate the realization
Solution Approach 1:
The patent introduces signal processing circuitry as an intermediary between the antenna elements and the excitation source. This intermediary layer implements the complex excitation coefficient distribution through programmable gain amplifiers and phase shifters, making the realization of super-directive patterns more practical by decoupling the theoretical coefficient design from the physical implementation constraints
Solution Approach 2:
The patent employs feedback mechanisms where the actual received signals from multiple elements are processed to estimate the direction of arrival, and this information is used to adjust the excitation coefficients in real-time. This feedback loop compensates for mutual coupling effects and fabrication tolerances, maintaining optimal directionality despite implementation challenges
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 system enhances the sensitivity pattern and directional resolution of electrically small antennas, enabling them to achieve sensitivity equivalent to larger aperture arrays, despite their physical size, by amplifying the phase difference between output signals, thus overcoming the limitations of small antenna arrays.
Implementation Method 1
The signal processing circuit includes a first resonant loop and a second resonant loop. The first resonant loop is mounted to receive the first signal from the first antenna. The second resonant loop is mounted to receive the second signal from the second antenna.
Data Source
AI summary
An electrically small receiver system is provided. The receiver system includes a plurality of antennas and a signal processing circuit. The plurality of antennas includes a first antenna configured to receive a first signal and a second antenna configured to receive a second signal. The signal processing circuit includes a first resonant loop and a second resonant loop. The first resonant loop is mounted to receive the first signal from the first antenna. The second resonant loop is mounted to receive the second signal from the second antenna. The first resonant loop and the second resonant loop are coupled such that the first output signal and the second output signal are generated as a function of the first signal and the second signal. A phase difference between the first output signal and the second output signal is greater than a phase difference between the first signal and the second signal.