Quasi-Isotropic Antenna Using Loop-Dipole Resonant Coupling
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Solution Overview
Problem
Implantable devices with small-sized antennas face challenges in achieving uniform radio wave radiation patterns, leading to reduced signal strength in specific directions, making it difficult for receiving devices to detect the signals effectively.
Innovation Solution
A quasi-isotropic antenna design that combines a loop antenna and a dipole antenna, where the dipole antenna resonates with the loop antenna to create orthogonal radiation patterns, ensuring uniform intensity in all directions without the need for separate power feeding to the dipole antenna, using a feeder connected only to the loop antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small-sized loop antenna is used in implantable devices, then the device size is reduced, but the radiation intensity decreases significantly in certain directions
Solution Approach 1:
The patent combines a loop antenna and a dipole antenna into a single integrated antenna structure. The loop antenna portion provides radiation in one orientation while the dipole antenna portion provides radiation in the orthogonal orientation, merging their radiation patterns to achieve uniform omnidirectional radiation without requiring separate antennas or feeders.
Solution Approach 2:
The integrated antenna structure serves multiple functions: it acts as both a loop antenna and a dipole antenna simultaneously, providing both magnetic dipole and electric dipole radiation characteristics. This multi-functionality allows a single small-sized antenna to achieve isotropic radiation patterns that would otherwise require multiple separate antennas.
2Device complexity
If a single loop antenna is used, then the device structure is simplified, but the radiation pattern shows significant intensity variation (at least 15 dB decrease) in predetermined directions
Solution Approach 1:
The patent merges the loop antenna and dipole antenna into a single continuous conductive structure without requiring separate feeders or complex switching mechanisms. The unified structure maintains simplicity while achieving uniform radiation through the combination of orthogonal radiation patterns from the loop and dipole portions.
3Loss of energy
If the dipole antenna length is adjusted for resonance, then the radiation efficiency is improved, but the antenna geometry becomes more constrained
Solution Approach 1:
The loop and dipole portions are merged into a single continuous conductive structure where the dipole portion's length is optimized for resonance at the operating frequency. This integrated approach allows the resonant dipole structure to achieve high radiation efficiency while the overall compact geometry is maintained through the shared conductive path with the loop portion.
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 quasi-isotropic antenna achieves improved radiation performance with a uniform intensity in all directions, reducing the variation between maximum and minimum signal strength to less than 4 dB, enhancing the ability of receiving devices to detect the signals compared to traditional single-loop antennas.
Implementation Method 1
a dipole antenna adjacent to the loop antenna, and configured to radiate a second radio wave by resonating based on a resonant-coupling with the loop antenna
Data Source
AI summary
A quasi-isotropic antenna includes: a feeder; a loop antenna configured to radiate a first radio wave based on a feeding from the feeder; and a dipole antenna adjacent to the loop antenna, and configured to radiate a second radio wave by resonating based on a resonant-coupling with the loop antenna, wherein a radiation pattern of the first radio wave is orthogonal to a radiation pattern of the second radio wave.